The natural course of idiopathic ketotic

hypoglycemia A retrospective cohort-study and systematic literature search

Rixt van der Ende

1964119

Research supervisor:

Dr. T.G.J. Derks

Research department:

Section of Metabolic Diseases, Beatrix Children’s Hospital, and Laboratory of Metabolic

Diseases, Department of Laboratory Medicine, and Center for Liver, Digestive and Metabolic

diseases; GUIDE. Hanzeplein 1, 9700 RB, Groningen. Tel: +31-50-3614147. E-mail:

t.g.j.derks@umcg.nl

2

TABLE OF CONTENTS

Keywords 3

Abbreviations 3

Abstract 4

Introduction 6

Methods 10

Results 11

Discussion 17

Conclusion 20

References 21

Appendices 24

3

Keywords:

Hypoglycemia – fasting – idiopathic ketotic hypoglycemia.

Abbreviations:

ADHD, attention deficit hyperactivity disorder; ALTE, apparent life threatening events; EEG,

electroencephalogram; EGP, endogenous glucose production; FFA, free fatty acid; FI, fasting

intolerance; GH, growth hormone; GGL, glycogenolysis; GNG, gluconeogenesis; GSD,

glycogen storage disease; IEM, inborn error of metabolism; IKH, idiopathic ketotic

hypoglycemia; KB, ketone body; PDD–NOS, pervasive developmental disorder – not

otherwise specified.

4

ABSTRACT

Idiopathic ketotic hypoglycemia (IKH) is the most common cause of fasting

intolerance and defined as recurrent neurohypoglycemic symptoms with ketosis in children.

IKH is a diagnosis per exclusion, of which the diagnostic tests do not indicate a traditional

monogenetic inborn error of metabolism (IEM). The etiology and pathophysiology of IKH are

incompletely understood and long-term follow-up data of IKH patients have not been reported

before. Therefore we performed this retrospective study on the natural course of IKH in a

well-selected cohort. In addition, we performed a systematic literature search.

Mean age at onset was 51.1 (± 5.9) months. More boys were diagnosed with IKH (41

out of 68 patients). Children with IKH were in general smaller than other children, median z-

score for height was -1.5 (range -3.2 - 3.7), and they were more vulnerable to diseases, like

infections (37%). We found clinical manifestations that have not been described before.

Common clinical manifestations in our cohort of IKH patients during follow-up were

convulsions (25%), apparent life threatening events (ALTE) (3%), developmental retardation

(13%), electroencephalogram (EEG) abnormalities (3%), attention deficit hyperactivity

disorder (ADHD) (9%), pervasive developmental disorder – not otherwise specified (PDD-

NOS) (9%), behavior disorders (13%), problems with eating (9%), asthma (13%) and eczema

(10%). Based on the systematic literature study, most common manifestations described, were

convulsions, cataracts, EEG abnormalities and developmental retardation.

This study increases the knowledge on the natural course of IKH. This has

implications for monitoring of IKH patients in the future. We recommend focusing on the

common clinical manifestations described in this study during the follow-up, to optimize the

development of patients.

SAMENVATTING

Idiopathische ketotische hypoglycemie (IKH) is de meest voorkomende oorzaak van

vastenintolerantie (FI) en gedefinieerd als terugkerende ketotische hypoglcyemieën bij

kinderen. De diagnose IKH wordt per exclusionem gesteld, als de diagnostische testen geen

andere traditionele monogenetische aangeboren fout in het metabolisme (IEM) kunnen

aantonen. De etiologie en pathofysiologie van IKH worden niet volledig begrepen en lange

termijn follow-up data zijn niet eerder beschreven. Daarom hebben wij een onderzoek naar

het natuurlijk beloop van IKH uitgevoerd, gebaseerd op een retrospectieve studie van een

goed geselecteerd cohort en een systematisch literatuuronderzoek.

De gemiddelde leeftijd waarop IKH zich voor het eerst presenteerde was 51.1 (± 5.9)

maanden. Jongens werden vaker gediagnosticeerd met IKH (41 van de 68 patiënten).

Kinderen met IKH waren kleiner dan andere kinderen, de mediaan z-score voor lengte was -

1.5 (range -3.2 - 3.7), en gevoeliger voor het krijgen van ziekten, zoals infecties (37%). In ons

cohort van patiënten hebben wij niet eerder beschreven klinische manifestaties gevonden.

Veel voorkomende klinische manifestaties waren convulsies (25%), apparent life threatening

events (ALTE) (3%), ontwikkelingsachterstand (13%), elektro-encefalografie (EEG)

afwijkingen (3%), attention deficit hyperactivity disorder (ADHD) (9%), pervasive

developmental disorder – not otherwise specified (PDD-NOS) (9%), gedragsproblemen

(13%), problemen met eten (9%), astma (13%) en eczeem (10%). In de literatuur waren de

meest beschreven klinische manifestaties convulsies, cataracts, EEG-afwijkingen en

ontwikkelingsachterstand.

Deze studie vergroot de kennis over het natuurlijk beloop van IKH. Dit heeft betekenis

voor het volgen van IKH-patiënten in de toekomst. Wij raden aan om te focussen op de veel

5

voorkomende klinische manifestaties, beschreven in dit onderzoek, om zo de ontwikkeling

van patiënten te optimaliseren.

6

INTRODUCTION

Glucose homeostasis in infants and children

In the post absorption fasting state, blood glucose concentrations are determined by both

endogenous glucose production (EGP) and peripheral glucose clearance/utilization. Adults are

able to maintain a normal blood glucose concentration for weeks [1]. In contrast, healthy

infants and children are not capable to maintain normal plasma glucose concentrations that

long. Even after a relatively short fast (24-36 hours), glucose concentration decreases [2, 3].

Fasting intolerance (FI) is intimately associated with perturbed glucose homeostasis.

Hormones and other factors, like cytokines, regulate the storage, mobilization and utilization

of glucose. After a meal, the plasma glucose concentration increases in normal individuals.

The glucose transporter 2 provides the transport of glucose into the pancreatic beta-cell,

where glucose is phosphorylated by glucokinase and metabolized via the glycolytic pathway.

An increase in the ATP/ADP ratio is the result, which causes insulin secretion. Conversely, a

reduction of insulin secretion is the result of a decrease in the ATP/ADP ratio, when blood

glucose concentrations are low [4].

When glucose concentration decreases, glycogenolysis (GGL) is stimulated by epinephrine

and glucagon. After a certain time, when the glycogen stores are not able to sustain GGL

anymore, gluconeogenesis (GNG), stimulated by growth hormone (GH) and cortisol, ensues.

These counter regulatory hormone responses are bigger in children than in adults during

controlled insulin-induced hypoglycemia [5, 6]. Substrates for gluconeogenesis (alanine,

lactate and glycerol) are derived from skeletal muscle and adipose tissue. Besides, the

mobilization and oxidation of fatty acids play a crucial role in the maintenance of glucose

homeostasis in infants and children. Free fatty acids (FFAs) and ketone bodies (KBs),

produced of fatty acids by the liver, can be used by different body tissues and provide energy

when blood sugar is low/during prolonged fasting. The brain cannot use FFAs, because they

are not transported across the blood-brain barrier. Therefore the brain is dependent on KBs as

an alternative energy source in a hypoglycemic condition [1].

The glucose utilization and EGP rate are higher in (young) children compared to adults [7]. In

adults the rate of glucose clearance/utilization in the overnight post absorptive state (14-hour

fast) is approximately 11 to 13 µmol/kg/min and 9.8 µmol/kg/min by 30 hours of fasting.

These rates are in infants and children nearly three times higher, 25 µmol/kg/min in the

overnight absorptive state and this value decreases to 23 µmol/kg/min after a 30- to 40-hour

fast [7, 8]. Recently, Huidekoper et al. constructed a regression model for EGP as a function

of age, and compared this with glucose supplementation using commonly used dextrose-based

saline solutions at fluid maintenance rate in children [9]. They found that with standard

dextrose-based saline solutions infused at fluid maintenance rate, only approximately 50% or

less of EGP is provided. With prolonged infusion of these solutions, the deficit between

exogenous glucose supplementation and EGP may induce a catabolic state and may ultimately

lead to hypoglycemia, especially in younger children.

More than 90% of the glucose is utilized by the brain in prematures and term infants. This

value decreases to approximately 40% in adults [4]. Infants and children are more susceptible

to hypoglycemia, because the proportion of brain mass to body size is relatively high

7

compared to adults and the rates of glucose turnover per kilogram of body weight in infants

and children is higher [7, 8].

Hypoglycemia in infants and children

Hypoglycemia is the most common metabolic emergency in childhood [10]. Severe,

prolonged or repeated episodes of hypoglycemia in infants and children can cause irreversible

brain damage. Therefore, early identification, management and identification of the cause are

extremely important.

Although the precise definition of hypoglycemia is a matter of debate, it has been defined as a

plasma glucose concentration of <2.6 mmol/L regardless of age [11]. For the interpretation of

plasma glucose value it is important to know the conditions preceding the collection of blood,

this because the plasma glucose concentration will be different following for example a meal

or an overnight fast and depends on the child’s age, gestation and/or weight. In children and

adults signs of hypoglycemia can be divided into two categories, signs caused by the

autonomic response to hypoglycemia and signs caused by neuroglycopenia. The autonomic

response includes sweating, weakness, tachycardia, tremor and feelings of nervousness and/or

hunger. These manifestations occur at a blood glucose concentration between 2.2 and 3.9

mmol/L. Signs of neuroglycopenia occur at a blood glucose concentration of approximately

0.6 to 2.8 mmol/L, with prolonged hypoglycemia, and include lethargy, irritability, confusion,

uncharacteristic behavior, hypothermia and in extreme low blood sugar concentrations,

seizure and coma [12]. The signs of hypoglycemia in infants are often nonspecific, but may

include the signs of neuroglycopenia. Examples of nonspecific symptoms during

hypoglycemia in infants are jitteriness, irritability, feeding problems, lethargy, cyanosis,

tachypnea and hypothermia.

Diagnostic process of hypoglycemia in infants and children

For infants and children with FI, the diagnostic follow-up can be very complex. Many

inherited hormonal and metabolic disorders are associated with FI, in which glucose

homeostasis is often perturbed. To clarify the pathogenesis/etiology of the various

hypoglycemic disorders, a systematic approach is important. First, a critical plasma sample is

obtained, following the anamnesis (age at onset, dietary factors, family history), physical

examination and a blood test that measures i.e. transaminases, lipids, lactate and

acylcarnitines. Results guide further testing. A possible further test is the elective fast. The

elective fast or fasting tolerance test is an invasive and potentially dangerous test and

therefore should only be performed under controlled conditions. Plasma concentrations of

glucose, KBs, lactate, alanine and insulin are measured and compared with normal values.

GH and cortisol plasma concentrations should be measured at the time of hypoglycemia. The

duration of the fast depends upon the child’s age and normal feeding pattern. Until a decade

ago, the elective fast or fasting tolerance test had been applied as an informative in vivo test.

Since the introduction of new laboratory techniques, like acylcarnitine profiling since the

1990ies and the more recent genetic developments, it is considered to be obsolete.

Idiopathic Ketotic Hypoglycemia

IKH is the most common cause of FI and defined as recurrent neurohypoglycemic symptoms

with ketosis in children [13]. Typical biochemical findings during a fasting tolerance test in

the hypoglycemic episode, that are consistent with IKH, are decreased insulin levels, normal

8

lactate and pyruvate concentrations and elevated GH, cortisol, FFAs and KBs. IKH is a

diagnosis per exclusion, of which the diagnostic tests do not indicate a traditional

monogenetic inborn error of metabolism (IEM). IKH typically presents in children between

the ages of eighteen months and five years, when the child encounters a catabolic stress such

as infection or periods of caloric restriction, and spontaneously remits by higher age [14].

Known is that there are more boys diagnosed with IKH.

The etiology and pathophysiology of IKH are incompletely understood. Different studies have

demonstrated that a normal glycemic response is evoked by glucagon in patients [15, 16].

This indicates a normal activity of glycogenolytic enzymes and the presence of hepatic

glycogen. Activities of fructose-1,6-diphosphatase and glucose-6-phosphatase, enzymes that

are responsible for steps in converting fructose and glycerol into glucose, are normal [17, 18].

Plasma glycerol levels are not different from those of control children, so this substrate is not

rate-limiting [18]. Besides responses to infusions of beta-hydroxybutyrate, a KB, are not

different in normal children [19]. At time of hypoglycemia, plasma insulin concentrations are

low [16, 17, 20] and glucagon and cortisol concentrations are increased [18]. Children with

IKH have normal venous lactate and pyruvate concentrations, but have hypoalaninaemia prior

to and during fasting [15, 18]. Glucocorticoid insufficiency can be excluded, because plasma

cortisol concentrations are higher in children with IKH and tests of the pituitary adrenal axis

are normal [15, 17]. Plasma glucagon and growth hormone do not differ compared to those of

normal children. Alanine, a gluconeogenic precursor, infusion in children with IKH, leads to a

rise in plasma glucose without prominent changes in blood lactate, pyruvate or insulin [16,

18]. This indicates that the entire gluconeogenic pathway is intact and so a gluconeogenic

enzyme defect can be excluded.

It could be hypothesized that IKH patients represent the lower tail of the Gaussian distribution

of fasting tolerance in children [21]. It is described that children with IKH frequently are

smaller than age-matched control subjects [15, 16, 20]. These smaller children could be more

vulnerable to hypoglycemia, because the proportion of brain mass to body size is relatively

high compared to other children. An imbalance in the suppression of glucose utilization,

which is the result of increasing concentrations of FFAs and

KBs in the blood, and the rate of hepatic glucose production, could also be the cause of IKH.

The hepatic glycogen stores could be depleted before the blood concentration of FFAs and

KBs has reached the certain level that is responsible for suppression of glucose utilization

[22]. Another possibility is an insufficient increase in renal gluconeogenesis. Proof for this

possibility is the spontaneous remission at a time when the proportion of brain mass to body

size is decreasing and endogenous substrate availability is increasing. Marcus et al. studied a

pair of homozygote twin boys, one of them had severe IKH from the age of fourteen months

and the other boy was apparently healthy [23]. In this study the boys were investigated at the

age of six. During a fasting tolerance test, the boy with IKH showed hypoglycemia after

eighteen hours. Three hours before he had ten times higher beta-hydroxybutyrate levels than

his brother, who showed no signs of hypoglycemia at that moment. The glucose production

rates and lipolysis rates were normal and similar. In the twin with IKH the plasma level of

beta-hydroxybutyrate increased five to ten times more during repeated 60-min infusions of

beta-hydroxybutyrate. This indicates a disturbed clearance or metabolism of beta-

hydroxybutyrate, in contrary to the results of earlier research described before [16]. They

concluded that, because the boys are homozygotic twins and only one of them is affected,

IKH is most likely caused by an altered imprinting of genes involved in regulating metabolic

pathways. Huidekoper et al. determined glucose kinetics during fasting in patients with IKH

in order to study the pathophysiology of hypoglycemia in IKH [14]. They found, during a

9

fasting tolerance test, a significant lower rate of EGP and lower mean GGL and GNG in the

five youngest subjects (age 2.5-3.9 years), who became hypoglycemic, compared to the older,

normoglycemic subjects. Also, plasma alanine levels were significantly lower at the end of

the test in the hypoglycemic subjects. They concluded that hypoglycemia in IKH is caused by

the inability to sustain an adequate EGP during fasting in view of the higher glucose

requirement in young children. The decrease in GGL is not accompanied by a significant

increase in GNG, possibly because of a limitation in the supply of alanine. Their results

support the hypothesis that IKH represents the lower tail of the Gaussian distribution of

fasting tolerance in children.

This study

The natural course of IKH is incompletely understood, because knowledge is mainly derived

from historical cross-sectional cohort studies. This is a retrospective longitudinal multicenter

cohort study performed in a well-selected cohort of IKH patients. The aims of this study are:

1. To describe the natural course of these 68 IKH patients and

2. To perform a systematic literature review on the natural course of IKH.

We hypothesize that children with IKH are more vulnerable to other diseases, like infections,

and children with IKH grow slower than other children. Children with IKH are unable to

sustain normal blood glucose levels in periods of higher glucose requirement, for example

moments of catabolic stress (infections) and growth. Children with IKH are slower in their

development than other children. Repeated episodes of hypoglycemia in infants and children

can irreversibly damage the central nervous system of these children.

10

METHODS

Retrospective cohort-study

Patients and methods

The section of Metabolic Diseases, Beatrix Children's Hospital, University Medical Center

Groningen is a tertiary center receiving referrals from the northeastern part of the

Netherlands. In this department in the period 1993-2012, 539 clinical fasting tolerance tests

have been performed in 476 patients. In an earlier JSM pilot project, from this cohort 68 IKH

patients have been identified, based upon the following criteria [24]:

1. Increased concentrations of KBs in plasma and urine.

2. Exclusion of a recognized hormonal disorder or monogenetic IEM, genetic disease

and/or known chronic disease.

3. Hypoglycemia as defined by the so-called Whipple’s triad [11]:

a. Clinical symptoms and signs likely to be attributed to hypoglycemia

b. Blood glucose concentrations below 2.6 mmol/L during attacks

c. Resolution of symptoms and signs after administration of glucose

Subsequently, a retrospective descriptive analysis of the clinical and biochemical

characteristics of these 68 IKH patients during the fasting tolerance test has been performed.

This is a retrospective longitudinal multicenter cohort study performed in these 68 patients to

describe the natural course of IKH. Long-term follow-up data was anonymously collected in

peripheral, referring hospitals by using a case record form (appendix). According to the

Medical Treatment Contracts Act, permission of patients or parents was not necessary.

Information recorded for each subject included gestational age, birth weight, gender, age at

onset, age at performing the fasting test, symptoms of presentation, growth characteristics,

severity of hypoglycemia, hospitalization, other diagnoses and relevant family-history.

Statistics

Data-analysis was performed by using SPSS Statistics. The Kolmogorov-Smirnov test was

used to determine whether the data was normally distributed or not. The mean and the SD of

the mean were presented when the data was normally distributed. The median and the range

were presented when the data was not normally distributed. Differences in variables between

subgroups (boys/girls) of the 68 IKH patients were analysed by using unpaired independent t-

tests and Wilcoxon-Mann-Whitney tests. A P value <0.05 was considered to be statistically

significant.

Systematic literature search

The objective of the systematic literature search was to describe the characteristics of IKH

patients in other studies. An electronic search was conducted. All EBSCO databases, the

Cochrane Library and PubMed were used for this search. Studies that describe more than 1

case were included. Excluded were articles written in other languages than English. The

Medical Subject Headings (MeSH) ‘hypoglycemia’ and ‘child’ and additionally the term

‘ketotic’ were used for the search.

11

RESULTS

Retrospective cohort-study

The group of IKH patients consisted of 41 boys and 27 girls from 67 families. Two girls were

sisters. According to our results the pregnancy period was shorter in boys diagnosed with IKH

than in girls. Mean age at onset was 51.1 (± 5.9) months. Children with IKH were in general

smaller than other children. Common clinical manifestations in our cohort of IKH patients

during follow-up were convulsions (25%), infections (37%), Apparent Life Threatening

Events (ALTE) (3%), developmental retardation (13%), electroencephalogram (EEG)

abnormalities (3%), Attention Deficit Hyperactivity Disorder (ADHD) (9%), Pervasive

Developmental Disorder – Not Otherwise Specified (PDD-NOS) (9%), behavior disorders

(13%), problems with eating (9%), asthma (13%), eczema (10%). None of the patients died

during follow-up. One patient developed a posttraumatic stress disorder after hospitalizations

for IKH. The sibling, diagnosed with arthrogryposis multiplex congenita, of one IKH patient

died in the period after a vaccination of fever. Six patients had a relative diagnosed with

epilepsy. Seven patients had relatives with a history of Diabetes Mellitus. Long-term follow-

up data are presented in the tables and figure below.

Table 1. Demographics of all IKH patients

Mean SE Median Range

Pregnancy period (weeks) 39 30-44

Birth weight (g) 3151 124

Age at onset (months) 51.1 5.9

Age at performing fasting tolerance test

(months)

51.8 13-188

Z-score height -1.5 -3.2-3.7

Z-score height during fasting tolerance test -0.3 -3.7-2.1

Z-score weight -0.2 0.2

Z-score weight during fasting tolerance test -0.1 -5.1-2.1

12

Z-score BMI during fasting tolerance test

-0.1 1.1

Target height boys during fasting tolerance

test (cm)

182.2 1.1

Target height girls during fasting tolerance

test (cm)

176.4 1.7

Lowest recorded glucose concentration

(mmol/L)*

3.9 0.2

Hospitalizations for IKH 2** 0-14

*Glucose concentrations during the fasting tests are not included.

**A total of 135 hospitalizations in 41 patients.

Figure 1. Clinical manifestations in IKH patients during follow-up

Table 2. Differences between boys and girls in demographics of the long-term follow-up

Mean male

(SE)

Median

male

[range]

Mean

female

(SE)

Median

female

[range]

P-value

Pregnancy period

(weeks)

37 (1) 40 [32-43] 0.043*

0 20 40 60 80 100

Convulsions

Infection

ALTE

Developmental retardation

EEG abnormalities

ADHD

PDD-NOS

Behavior disorder

Problems with eating

Eczema

Asthma

Clinical manifestations

Percentage

13

Birth weight (g) 3205 (202) 2976 (276) 0.77

Age at onset (months) 39 (8) 36 (10) 0.96

Age at performing fasting

tolerance test (months)

53 [17-

201]

70 (22) 0.26

Z-score height (cm) -1.0 [-2.7-

2.0]

-2.0 [-3.2-

3.7]

0.055

Z-score height during

fasting tolerance test (cm)

-0.3 [-3.7-

1.2]

-0.9 (0.3) 0.073

Z-score weight (kg) 0.0 [-3.3-

2.5]

-0.2 (0.3) 0.19

Z-score weight during

fasting tolerance test (cm)

-0.7 (0.4) -1.0 (0.3) 0.33

Z-score BMI during

fasting tolerance test

(kg/m3)

-0.7 (0.4) -1.0 (0.3) 0.87

Target height during

fasting tolerance test (cm)

182.2 (1.1) 176.4 (1.7) 0.003*

Lowest recorded glucose

concentration (mmol/L)*

3.7 (0.5) 3.8 (0.8) 0.12

Hospitalizations for IKH

(number)

4.1 (1.1) 3.0 (0.7) 0.75

*Statistically significant difference

Systematic literature search

The search generated a total of 165 abstracts in all EBSCO databases, 0 articles in the

Cochrane Library and 95 articles in PubMed. In addition, a hand search was performed in

reference lists of identified studies for relevant literature. 237 articles were excluded after

reviewing titles and abstracts. 23 articles described more than 1 case and were suitable for this

systematic literature review. Table 3 shows an overview of IKH in the literature. In literature,

more boys than girls with IKH were described and age at onset varied from 7 to 72 months.

Most common manifestations described were convulsions, cataracts, EEG abnormalities and

developmental retardation.

14

Table 3. IKH in literature, based on papers with > 1 case.

First author Year Number

of IKH

patients

Gender

(F-M)

Age at onset

(months;

range)

Clinical data

Colle [15] 1964 8 3-5 18-60 7/8 morning convulsions

2/8 born prematurely

1x case bilateral cataracts

Senior [21] 1969 8 0-8 8/8 seizures

Kogut [25] 1696 13 4-9 9-48* 13/13 morning seizures

7/13 low birth weight

6/13 distant relatives with

a history of Diabetes

Mellitus

2x affected siblings

1x affected mother

6/13 intelligence quotients

or developmental

quotients below 90

5x EEG abnormalities

1x severe convulsive

disorder

1x coronal synostosis with

sever spasticity

1x bilateral cataract

1x severe visual

impairment secondary to

optic atrophy and

congenital colobomata

Wilson [26] 1969 14 4-10 9-36 Birth weight: 1500-4500 g

3/14 mentally retarded

5/14 convulsions

1x EEG abnormalities

1x affected siblings, 3rd

brother died in coma

1x affected mother

1x poor vision

2x cataract

3/14 born prematurely

Grunt [20] 1970 8 3-5 8-31 Mean birth weight: 2480 g

Mean maternal age: 31

years

5/8 pregnancies:

preeclampsia, toxaemia or

other significant illness

2x cataract

15

4x EEG abnormalities

Loridan [19] 1970 4

Habbick [27] 1971 20 6-14 17/20 convulsions

6 girls and 14 boys below

the 10th

percentile of

weight for maturity

2/20 mentally retarded

2x siblings with a history

of convulsions

4 boys were the smaller

and lighter of non-

identical twins

Pagliara [16] 1972 8 3-5 7/8 seizures

1x EEG abnormalities

2/8 presented with coma

1x mental retardation

Rosenbloom

[28]

1972 2 1-1 7-48 1 patient treated by

glucocorticoids

Chaussain

[29]

1973 10 4-6 Each case had at least one

seizure

Sizonenko

[30]

1973 5 0-5 18-27 5/5 convulsions

2x twins with an

unaffected sibling

1x mental retardation

3/5 heights and weights in

the lower percentiles

Chaussain

[31]

1974 6 1-5

Haymond

[18]

1974 10 3-7 13-63 (mean

34±5)

Lowest spontaneous blood

glucose 12-43 mg/100 ml

(mean 27 ± 3)

Birth weight: 1620-3780 g

(mean 2937 ± 287)

Mean height at the 26th

percentile (± 8) and mean

weight at the 35th

(± 8)

Murphy [32] 1975 5 4-1 12-31 Birth weight: 2.7-4.5 kg

1/5 convulsions

1x EEG abnormalities

Falorni [33] 1978 5 1-4 Birth weight: 2.65-4.20 kg

1 patient presented with

neonatal hypoglycemia

3/5 family history of

hypoglycemia

2x EEG abnormalities

Dahlquist

[34]

1979 6 2-4 18-72 3/6 small for gestational

age

3/6 neonatal symptomatic

16

hypoglycemia

4/6 convulsions

Wolfsdorf

[35]

1982 18 5-13

Saudubray

[36]

1982 6

Wets [37] 1982 40 Mean age of

presentation:

20 months

15/40 (9 male, 6 female)

developed cataracts

Birth weight of these 15

patients: 1.298-4.605 g

(mean: 2060 g)

Convulsions and EEG

abnormalities in more than

half of these patients

Age at onset in these 15

patients: 5-47 months

Pershad [38] 1998 18 6-12 Weight of 5/18 below the

25th

percentile

Daly [39] 2003 24 9-15 Mean age of

presentation:

30.8 months

Weight of 68% below the

25th

percentile

30% presented with

seizures

5% presented with coma

Birth weight: 2.1-4.0 kg

Gestational age: 28-40

weeks

No patient was found to

have a hypoglycemic

episode after 7 years of

age

Matsubara

[40]

2003 18 4-14 Convulsions

Bodamer [22] 2006 9 2-7

Huidekoper

[14]

2008 12 4-8 SD for height varied from

-2.0 to 2.0 and SD for

weight from -0.7 to 3.0 kg

Nessa [41]

2012 50 24-26 12-72 Mean birth weight: 3243 g

(1235-4720 g)

3/50 were born

prematurely (28-36

weeks)

3/50 born presenting

intrauterine growth

retardation

Total 327 93-184 7-72

* 1 case at 0 months.

17

DISCUSSION

This is a retrospective, longitudinal study on the natural course of 68 IKH patients. Mean age

at onset was 51.1 (± 5.85) months. More boys are diagnosed with IKH (41 out of 68 patients).

Children with IKH are in general smaller than other children and they are more vulnerable to

diseases, like infections (37%). We found clinical manifestations that have not been described

in literature before. Common clinical manifestations in our cohort of IKH patients during

follow-up were convulsions (25%), ALTE (3%), developmental retardation (13%), EEG

abnormalities (3%), ADHD (9%), PDD-NOS (9%), behavior disorders (13%), problems with

eating (9%), asthma (13%) and eczema (10%). In addition, based on the systematic literature

study, most common manifestations described, were convulsions, cataracts, EEG

abnormalities and developmental retardation (table 3).

Long-term follow-up data of IKH patients have not been reported before. In our cohort of

IKH patients we found clinical manifestations that have not been described in literature

before. Monitoring of all manifestations should be done to optimize the development of IKH

patients.

A limit of our study was incomplete long-term follow-up data of patients. Data recorded for

each subject (gestational age, birth weight, gender, age at onset, age at performing the fasting

test, symptoms of presentation, growth characteristics, severity of hypoglycemia,

hospitalization, other diagnoses and relevant family-history) in peripheral, referring hospitals

was for most patients not complete, because in both paper and electronic medical files

information was missing.

After establishment of the diagnosis, hospital admissions for IKH were required in 41 patients

and varied from 1 to 14 times during the follow-up (a total of 135 hospital admissions).

Intravenous administering of glucose was provided during most of these admissions. Hospital

admissions were equally dived between different peripheral, referring hospitals.

The median z-score for height in our patients was -1.5 and varied from -3.2 to 3.7. It can be

argued that children with IKH do have a short stature. This supports the hypothesis that IKH

represents the lower tail of the Gaussian distribution. These smaller children could be more

vulnerable for hypoglycemia, because the proportion of brain mass to body size is relatively

high compared to other children [21]. On the other hand, long-term follow-up growth data

was not available of all IKH patients. It could be the case that only the growth data of children

with growth retardation is recorded in the follow-up, so that the mean z-score is not

representative for all IKH patients.

The median z-score for height during the fasting tolerance test was -0.3 and varied from -3.7

to 2.1. This value differs from the z-score for height in general. It could be the case that late

evening feeding is prescribed in children with fasting intolerance and that this intervention

has had a positive influence on the growth of children with IKH.

The mean lowest recorded glucose concentration upon follow-up was 3.9 (± 0.2) mmol/L.

This mean value is higher than the for hypoglycemia defined blood glucose concentration of

<2.6 mmol/L [11]. This can be explained by several factors. First, long-term follow-up data of

most patients was not complete. For example in periods of hypoglycemia, laboratory values,

like blood glucose concentrations, were not recorded in both paper and electronic medical

18

files. Second, most blood glucose concentrations were measured in periods of

normoglycemia. Last, it could be the case that measurements have been done in older

patients, in which IKH spontaneously had remitted.

In our group of IKH patients, mean age at onset was 51.1 (± 5.9) months. The age of onset

varied from 1 to 183 months. This is partially in agreement with findings in previous studies

(table 3), age at onset in literature varied from 7 to 72 months. The variation in age is bigger

in our study. This bigger variation can be explained by the fact that in our study a large group

of patients (n=68) is characterized. This large group of patients consisted of all patients

diagnosed with IKH in the University Medical Center Groningen, Beatrix Children's Hospital,

section of metabolic diseases in the period 1993-2012. In previous studies, fewer cases were

described, in most of these previous studies a selection of patients had been made.

Only target height during the fasting test and pregnancy period differ significantly between

boys and girls. Differences between boys and girls with IKH have not been described before

and this study confirms that IKH presents similar in boys and girls.

Obviously our group of 68 patients consisted of far more male than female patients.

Theoretically, this could mean ‘under diagnosing’ of X-linked diseases in which patients

present with hypoglycemia, like glycogen storage disease (GSD) type IX. It was recently

reported that especially GSD IX is an unappreciated cause of IKH [42]. GSD IX should

therefore be considered in boys with IKH. To exclude GSD IX in all male IKH patients,

DNA-analysis should be done.

In previous studies (table 3) cataracts have been described in IKH patients. Cataract is

diagnosed in none of our 68 IKH patients. Possible under diagnosing of cataracts in our IKH

patients could be an explanation for this. Eyes of IKH patients in our metabolic center are not

regularly checked. Because cataracts in IKH patients are a common finding in other studies,

we suggest including eye examination in the follow-up of our IKH patients.

This study increases the knowledge on the natural course of IKH. This has implications for

monitoring of IKH patients in the future. We recommend focusing on the common clinical

manifestations described in this study during the follow-up, to optimize the development of

patients.

Future perspectives

Although the etiology of IKH is still not known, there are several hypotheses. One may argue

that these patients simply represent the lower tail of the Gaussian distribution of fasting

tolerance. Furthermore, it cannot be excluded that the cohort of IKH-patients includes IEMs

that are difficult to diagnose in plasma and/or urine. This was recently described for GSD IX

[42] and for mutations in the MCT1 transporter, the transporter that catalyzes the transport of

monocarboxylates across the plasma membrane and is pivotal for import of ketones in extra

hepatic tissues [43]. Mutations in genes involved in glycogen synthesis and degradation were

commonly found in children with idiopathic ketotic hypoglycemia. Van Hasselt et al. showed

that contrary to the current concept of freely diffusing ketone bodies, facilitated transport of

ketones by MCT1 is essential to allow adequate ketone utilization and maintain acid-base

balance. IKH could also be caused by synergistic heterozygosity and hence, considered as an

inborn variation of metabolism instead of a monogenetic disorder. The concept of synergistic

heterozygosity has been described as concurrent partial defects in more than one pathway or

19

at multiple steps in one pathway in patients with an IEM. Vockley et al. hypothesized that

patients diagnosed with an IEM exhibit clinically significant reduction in energy metabolism

related tot the compound effects of more partial defects. Based on the frequencies of known

disorders of energy metabolism, they propose that synergistic heterozygosity may represent a

relatively common mechanism of disease [44]. Schuler et al. have used mice to test the

concept of synergistic heterozygosity. They found that physiologic reduction of the beta-

oxidation pathway, characterized as cold intolerance, occurred in mice with double or triple

heterozygosity and these results substantiate the concept of synergistic heterozygosity and

illustrate the potential complexity involved in diagnosis and characterization of IEM in

humans [45]. We propose exome sequencing as a next step to unravel the etiology and to

generate a genetic platform of IKH.

During the fasting tests of the 68 patients in this study, time series of blood and urine samples

have been obtained at regular intervals for analysis of kinetic metabolic parameters. Kinetic

metabolic parameters include glucose, lactate, pyruvate, blood gass analysis, hormones

(insulin, cortisol, glucagon, growth hormone), free fatty acids, 3-hydroxybutyrate,

acetoacetate, 21 acylcarnitines and 23 amino acids. Besides, timed urine samples have been

collected for organic acid analysis. These parameters have been analysed and will, together

with the long-term follow-up data of this study, lead to the selection of a homogenous group

of 20 IKH patients for a subsequent exome sequencing project.

Hypoglycemia is the most common metabolic emergency in childhood [10]. Severe,

prolonged or repeated episodes of hypoglycemia in infants and children can cause irreversible

brain damage. Therefore, early identification, management and identification of the cause are

extremely important. Analysing a critical plasma sample is the gold standard in the diagnostic

process, following the anamnesis and physical examination. A possible further test is the

elective fast. The elective fast of fasting tolerance test is an invasive and potentially dangerous

test and therefore should only be performed under controlled conditions. An alternative for

the elective fast could be exome sequencing. Exome sequencing could importantly improve

the diagnostic process for patients after only drawing one blood sample. This test would be

fast, relatively cheap, non-invasive and safe.

Besides a subsequent exome sequencing project to unravel the etiology and to generate a

genetic platform of IKH, we will perform a study on the contribution of GSD in our cohort of

IKH patients by exome sequencing. The ketotic GSD types 0, III, VI, IX and XI are

associated with fasting ketotic hypoglycemia. These types are considered relatively mild

compared to GSD type I and can be misinterpreted as IKH or ketolysis defects. We

hypothesize that GSD types 0, III, VI, IX and XI can be identified in our cohort of IKH

patients. For exome sequencing we will first apply in-solution hybrid capturing methods to

target all exons, in total comprising ~37 Mb (Agilent Technologies). The sequences of the

captured DNA fragments will be determined by massive parallel sequencing using the

Illumina Genome Bioanalyzer II. Following, we will focus on class IV and V mutations in

genes involved in glycogen synthesis and degradation to study the contribution of GSD.

20

CONCLUSION

IKH is associated with significant co-morbidity after establishment of the diagnosis. Common

clinical manifestations in IKH patients were convulsions, ALTE, developmental retardation,

EEG abnormalities, ADHD, PDD-NOS, behavior disorders, problems with eating, asthma,

eczema and cataracts. Children with IKH were in general smaller than other children and they

were more vulnerable to diseases, like infections. Mean age at onset was 51.1 (± 5.85)

months. More boys were diagnosed with IKH. We recommend focusing on the common

clinical manifestations described in this study during the follow-up, to optimize the

development of patients.

21

REFERENCES

[1] Cahill GF, Herrera MG, Morgan AP, Soeldner JS, Steinke J, Levy PL, et al. Hormone-fuel

interrelationships during fasting. J Clin Invest 1966 Nov;45(11):1751-1769.

[2] Chaussain JL, Georges P, Calzada L, Job JC. Glycemic response to 24-hour fast in normal

children: III. Influence of age. J Pediatr 1977 Nov;91(5):711-714.

[3] Haymond MW, Karl IE, Clarke WL, Pagliara AS, Santiago JV. Differences in circulating

gluconeogenic substrates during short-term fasting in men, women, and children. Metabolism

1982 Jan;31(1):33-42.

[4] Haymond MW, Sunehag A. Controlling the sugar bowl. Regulation of glucose

homeostasis in children. Endocrinol Metab Clin North Am 1999 Dec;28(4):663-694.

[5] Huopio H, Shyng SL, Otonkoski T, Nichols CG. K(ATP) channels and insulin secretion

disorders. Am J Physiol Endocrinol Metab 2002 Aug;283(2):E207-16.

[6] Cornblath M, Schwartz R. Disorders of Carbohydrate Metabolism in Infancy. Blackwell

Publications, Cambridge, MA 1991.

[7] Haymond MW, Howard C, Ben-Galim E, DeVivo DC. Effects of ketosis on glucose flux

in children and adults. Am J Physiol 1983 Oct;245(4):E373-8.

[8] Bier DM, Leake RD, Haymond MW, Arnold KJ, Gruenke LD, Sperling MA, et al.

Measurement of "true" glucose production rates in infancy and childhood with 6,6-

dideuteroglucose. Diabetes 1977 Nov;26(11):1016-1023.

[9] Huidekoper HH, Ackermans MT, Ruiter AF, Sauerwein HP, Wijburg FA. Endogenous

glucose production from infancy to adulthood: a non-linear regression model. Arch Dis Child

2014 Jul 4.

[10] Aynsley-Green A. Hypoglycemia in infants and children. Clin Endocrinol Metab (1982),

11 (1): 159-94.

[11] Koh, T.H. Aynsley-Green, A. Tarbit, M. Eyre, J. A. Neural dysfunction during

hypoglycaemia. Arch Dis Child (1988), 63:1353-1358.

[12] Cryer PE. Banting Lecture. Hypoglycemia: the limiting factor in the management of

IDDM. Diabetes 1994 Nov;43(11):1378-1389.

[13] Thomas M, Jacob JJ, Alexander P. Idiopathic ketotic hypoglycemia presenting as febrile

seizures. Indian J Pediatr 2010 Dec;77(12):1448-1449.

[14] Huidekoper HH, Duran M, Turkenburg M, Ackermans MT, Sauerwein HP, Wijburg FA.

Fasting adaptation in idiopathic ketotic hypoglycemia: a mismatch between glucose

production and demand. Eur J Pediatr 2008 Aug;167(8):859-865.

[15] Colle E, Ulstrom RA. Ketotic Hypoglycemia. J Pediatr 1964 May;64:632-651.

22

[16] Pagliara AS, Kari IE, De Vivo DC, Feigin RD, Kipnis DM. Hypoalaninemia: a

concomitant of ketotic hypoglycemia. J Clin Invest 1972 Jun;51(6):1440-1449.

[17] Senior B, Loridan L. Gluconeogenesis and insulin in the ketotic variety of childhood

hypoglycemia and in control children. J Pediatr 1969 Apr;74(4):529-539.

[18] Haymond MW, Karl IE, Pagliara AS. Ketotic hypoglycemia: an amino acid substrate

limited disorder. J Clin Endocrinol Metab 1974 Apr;38(4):521-530.

[19] Loridan L, Senior B. Effects of infusion of ketones in children with ketotic

hypoglycemia. J Pediatr 1970 Jan;76(1):69-74.

[20] Grunt JA, McGarry ME, McCollum AT, Gould JB. Studies of children with ketotic

hypoglycemia. Yale J Biol Med 1970 Jun;42(6):420-438.

[21] Senior B. Ketotic hypoglycemia. A tale (tail) of Gauss? J Pediatr 1973 Mar;82(3):555-

556.

[22] Bodamer OA, Hussein K, Morris AA, Langhans CD, Rating D, Mayatepek E, et al.

Glucose and leucine kinetics in idiopathic ketotic hypoglycaemia. Arch Dis Child 2006

Jun;91(6):483-486.

[23] Marcus C, Alken J, Eriksson J, Blom L, Gustafsson J. Insufficient ketone body use is the

cause of ketotic hypoglycemia in one of a pair of homozygotic twins. J Clin Endocrinol

Metab

[24] Alkén J. Glucose and Ketone Body Metabolism: With Emphasis on Ketotic

Hypoglycemia (thesis). Stockholm, Sweden: Karolinska Institute, 2008. Availabele at:

http://diss.ki.b.ki.se/2008/978-91-7357-502-7/thesis/pdf

[25] Kogut MD, Blaskovics M, Donnell GN. Idiopathic hypoglycemia: a study of twenty-six

children. J Pediatr 1969 Jun;74(6):853-871.

[26] Wilson WA. Ocular findings in ketotic hypoglycemia. Trans Am Ophthalmol Soc

1969;67:355-368.

[27] Habbick BF, McNeish AS, Stephenson JB. Diagnosis of ketotic hypoglycaemia of

childhood. Arch Dis Child 1971 Jun;46(247):295-300.

[28] Rosenbloom AL, Tiwary CM. Ketotic (idiopathic glucagon unresponsive)

hypoglycaemia. Catecholamine excretion and effects of ephedrine therapy. Arch Dis Child

1972 Dec;47(256):924-926.

[29] Chaussain JL. Glycemic response to 24 hour fast in normal children and children with

ketotic hypoglycemia. J Pediatr 1973 Mar;82(3):438-443.

[30] Sizonenko PC, Paunier L, Vallotton B, Cuendet GS, Zahnd G, Marliss EB. Response to

2-deoxy-D-glucose and to glucagon in "ketotic hypoglycemia" of childhood: evidence for

epinephrine deficiency and altered alanine availability. Pediatr Res 1973 Dec;7(12):983-993.

23

[31] Chaussain JL, Georges P, Olive G, Job JC. Glycemic response to 24-hour fast in normal

children and children with ketotic hypoglycemia: II. Hormonal and metabolic changes. J

Pediatr 1974 Dec;85(6):776-781.

[32] Murphy A, Raftery J. Ketotic hypoglycaemia. Ir Med J 1975 Dec 27;68(23):586-588.

[33] Falorni A, Massi-Benedetti F, Sposito M, Barboni G, Lato M. Insulin and glucagon

secretion in the ketotic (idiopathic glucagon unresponsive) hypoglycemia of childhood. J

Endocrinol Invest 1979 Jan-Mar;2(1):51-57.

[34] Dahlquist G, Gentz J, Hagenfeldt L, Larsson A, Low H, Persson B, et al. Ketotic

hypoglycemia of childhood--a clinical trial of several unifying etiological hypotheses. Acta

Paediatr Scand 1979 Sep;68(5):649-656.

[35] Wolfsdorf JI, Sadeghi-Nejad A, Senior B. Hypoalaninemia and ketotic hypoglycemia:

cause or consequence? Eur J Pediatr 1982 Feb;138(1):28-31.

[36] Saudubray JM, Marsac C, Limal JM, Dumurgier E, Charpentier C, Ogier H, et al.

Variation in plasma ketone bodies during a 24-hour fast in normal and in hypoglycemic

children: relationship to age. J Pediatr 1981 Jun;98(6):904-908.

[37] Wets B, Milot JA, Polomeno RC, Letarte J. Cataracts and ketotic hypoglycemia.

Ophthalmology 1982 Sep;89(9):999-1002.

[38] Pershad J, Monroe K, Atchison J. Childhood hypoglycemia in an urban emergency

department: epidemiology and a diagnostic approach to the problem. Pediatr Emerg Care

1998 Aug;14(4):268-271.

[39] Daly LP, Osterhoudt KC, Weinzimer SA. Presenting features of idiopathic ketotic

hypoglycemia. J Emerg Med 2003 Jul;25(1):39-43.

[40] Matsubara T, Yoshitomi T, Kaneko M, Ichiyama T, Furukawa S. Ketotic hypoglycemia

in patients with allergic diseases. Pediatr Int 2003 Dec;45(6):653-655.

[41] Nessa A, Kumaran A, Kirk R, Dalton A, Ismail D, Hussain K. Mutation al analysis of

the GYS2 gene in patients diagnosed with ketotic hypoglycaemia. J Pediatr Endocrinol

Metab. 2012;25(9-10):963-967.

[42] Brown LM, Corrado MM, van der Ende RM, Derks TG, Chen MA, Siegel S, et al.

Evaluation of glycogen storage disease as a cause of ketotic hypoglycemia in children. J

Inherit Metab Dis 2014 Jul 29.

[43] Van Hasselt PM, Ferdinandusse S, Monroe GR, Ruiter, JPN, Turkenburg M, Geerlings

MJ, et al. Monocarboxylate transporter type 1 deficiency impairs ketone utilization and causes

profound ketoacidosis upon catabolic stress [abstract]. SSIEM annual symposium 2014.

[44] Vockley J, Rinaldo P, Bennett MJ, Matern D, Vladutiu GD. Synergistic heterozygosity:

disease resulting from multiple partial defects in one or more metabolic pathways. Mol Genet

Metab 2000 Sep-Oct;71(1-2):10-18.

24

[45] Schuler AM, Gower BA, Matern D, Rinaldo P, Vockley J, Wood PA. Synergistic

heterozygosity in mice with inherited enzyme deficiencies of mitochondrial fatty acid beta-

oxidation. Mol Genet Metab 2005 May;85(1):7-11.

25

APPENDICES

Appendix 1. Case Record Form

CASE RECORD FORM LONG-TERM FOLLOW-UP IKH PATIENTS

Patient initials:

Sex:

Date of birth:

Birth weight:

Date of fasting test:

Date of recording:

Medical history:

Family-history (i.a. consanguinity, older/younger brothers/sisters?):

Outpatient (0) and hospital admissions (1) before fasting test:

Date —/—/—

Date —/—/—

Date —/—/—

Date —/—/—

Reason 0/1

Anamnesis (y/n)

Hypoglycaemia

Vomiting

Drinking

Hepatomegaly

Hypotonia

Convulsions

26

Muscle pain

Exercise intoleration

Syncope

Temperature (ºC)

Growth parameters

Height (cm)

Height (SD)

Weight (kg)

Weight (SD)

Weight for height (SD)

BMI (kg/m2)

BMI (SD)

Head circumference

(cm)

Head circumference

(SD)

Physical examination

Temperature (ºC)

Blood pressure (mm

Hg)

Neurological status

(GCS, coma,

convulsions)

Muscle tone

(hypertonic, hypotonic,

normal)

Sweating

Liver size (cm below

rib cage)

Heart palpitations

Labaratory values

27

Blood

Glucose (mmol/L)

Lactate (mmol/L)

Cortisol (mmol/L)

Insulin (mmol/L)

Hemoglobin (mmol/L)

GH (mmol/L)

ASAT (U/L)

ALAT (U/L)

LDH (U/L)

CK (U/L)

Ketones (y/n)

3-Beta-hydroxybutyrate

(mmol/L)

Pyruvate (mmol/L)

Acetoacetate (mmol/L)

Carnitine free (umol/L)

Carnitine total (umol/L)

Blood Gass (a, v or c?)

pH

pCO2 (kPa)

pO2 (kPa)

HCO3- (mmol/L)

BE

Free fatty acids

(umol/L)

NH3 (umol/L)

Urine

Ketones (y/n)

3-Beta-hydroxybutyrate

(mmol/molkreat)

Acetoacetate

(mmol/molkreat)

28

N-hexanoylglycine

(mmol/molkreat)

N-

phenylpropionylglycine

(mmol/molkreat)

N-suberylglycine

(mmol/molkreat)

Adipic acid

(mmol/molkreat)

Suberic acid

(mmol/molkreat)

Sebacic acid

(mmol/molkreat)

Dicarbonaturia (y/n)

Duration

hospitalization (days)

Medication

Outpatient (0) and hospital admissions (1) after fasting test:

Date —/—/—

Date —/—/—

Date —/—/—

Date —/—/—

Reason 0/1

Anamnesis (y/n)

Hypoglycaemia

Vomiting

Drinking

Hepatomegaly

Hypotonia

Convulsions

Muscle pain

Exercise intoleration

Syncope

29

Temperature (ºC)

Growth parameters

Height (cm)

Height (SD)

Weight (kg)

Weight (SD)

Weight for height (SD)

BMI (kg/m2)

BMI (SD)

Head circumference

(cm)

Head circumference

(SD)

Physical examination

Temperature (ºC)

Neurological status

(GCS, coma,

convulsions)

Muscle tone

(hypertonic, hypotonic,

normal)

Sweating

Liver size (cm below

rib cage)

Heart palpitations

Neurological

abnormalities

Living situation

Education (special

education, IQ-tests)

Assistance

(physiotherapist,

psychologist)

30

Particulars

development

(motoric or

psychologic or

social)

EEG

ECG

Labaratory values

Blood

Glucose (mmol/L)

Lactate (mmol/L)

Cortisol (mmol/L)

Insulin (mmol/L)

GH (mmol/L)

ASAT (U/L)

ALAT (U/L)

LDH (U/L)

CK (U/L)

Ketones (y/n)

3-Beta-hydroxybutyrate

(mmol/L)

Pyruvate (mmol/L)

Acetoacetate (mmol/L)

Carnitine free (umol/L)

Carnitine total (umol/L)

Blood Gass (a, v or c?)

pH

pCO2 (kPa)

pO2 (kPa)

HCO3- (mmol/L)

BE

Free fatty acids

(umol/L)

31

NH3 (umol/L)

Urine

Ketones (y/n)

3-Beta-hydroxybutyrate

(mmol/molkreat)

Acetoacetate

(mmol/molkreat)

N-hexanoylglycine

(mmol/molkreat)

N-

phenylpropionylglycine

(mmol/molkreat)

N-suberylglycine

(mmol/molkreat)

Adipic acid

(mmol/molkreat)

Suberic acid

(mmol/molkreat)

Sebacic acid

(mmol/molkreat)

Dicarbonaturia (y/n)

Duration

hospitalization (days)

Medication