PHENYLKETONURIA (PKU)

Case Study Presentation

Cassidy Baerg

NUTR 426

OBJECTIVES

1. To recognize signs and symptoms associated with a PKU diagnosis.

2. To gain an elementary understanding of what causes this disease state.

3. To outline a basic intervention plan for a patient with PKU.

WHAT IS PKU?

PKU is an inherited amino acid disorder in which the essential amino acid phenylalanine is unable to be converted into tyrosine due to a an absence of Phenylalanine reductase or dihydropteridine reductase.

TWO TYPES

1.Classic PKU

2.Non-variant PKU

EPIDEMIOLOGY

According to the National Institute of Health PKU occurs in about 1 in 10,000-15,000 newborns in the United States.

PKU occurs more often in Caucasian and Native American populations than in African American or Hispanic populations.

DIAGNOSIS:

In the United States newborns are screened for PKU approximately 48 hrs after birth.

A Guthrie or heel prick test is used to test for PKU.

Classic PKU occurs when plasma phenylalanine levels exceed 20 mg/dL (1200 µmol/L) without intervention.

http://www.youtube.com/watch?v=85f7-C4n9kY

PATIENT D.O.

Caucasian female. Born at 38 weeks gestation. Birth weight = 5 pounds 7 oz. Length = 18 in. Head Circumference 12.6 in. Apgar: 5 and 6 at 1 min. and 5 min. respectively. Guthrie test came back positive for PKU.

plasma phenylalanine concentration was 8.5 mg/ dL or 508 mol/ L (Normal = 0.5 mg/dL-1.7 mg/dL )

Second Guthrie test on day 6, 22.0 mg/ dL or 1321 mol phenylalanine/ L plasma.

ASSESSMENT

Small For Gestational Age (Preterm) No Asymmetrical Growth Retardation Below Normal Apgar Difficult Birth High Phe concentrations Positive Guthrie Test For PKU

NUTRITION RX:

Started on PKU diet at 7 Days Old. Estimated Needs (initial):

Phe = 70mg/kg = 2.82 kg (5 # 4 oz at 6 days old) = 197.59 mg

Pro = 3.5 g/kg = 2.82 kg x 3.5 = 9.87 g Energy = 120 kcals/kg = 338.4 Fluid = mL/kg = 148mLx 2.82 = 417.36

mL

DIAGNOSIS: SAMPLE PES:

Excessive bioactive substances intake (too much Phe RT excessive intake of foods high in Phe amino acids AEB a Phe blood plasma concentration of 26.4 mg/dL at 6 days old.

Excessive bioactive substances intake (too much Phenylalanine) RT nutrition-related knowledge deficit AEB increased levels of Phe and a Guthrie test positive for PKU.

INTERVENTION

Control Phe blood plasma concentrations by getting the mother’s breast milk tested for Phe levels.

Augment diet with an infant formula low in Phe such as Periflex

Educate parents about PKU and a diet low in Phe amino acids.

Discuss possible nutrient deficiencies with a low Phe diet such as Kcals, iron, calcium, B12 and Vit D.

Emphasize the importance of regular visits with the RD.

MONITORING AND EVALUATION

Monitor lab values for Phe/Tyr. Monitor albumin/prealbumin. Do a 24 hr diet recall and typical diet

recall in order to assess Ca, Vit D, and B12 status.

Evaluate the effectiveness of the nutrition education component

FOLLOW-UP

D.O. breastfeed for 11 mo. Phe levels within acceptable range. Family adjusting well to low Phe diet. Food introduction similar to normal

children.

At 13 mo. Phe increased…

IN CLASS ACTIVITY

Question? Why did D.O.’s Phe suddenly increase?

ANSWERS: PER 100G EDIBLE PORTION

Low High

Apple Marshmallo

ws Sugar Tomato Carrot Peaches Grapefruit

Head Lettuce

White Rice

Egg White Tofu Beef Seaweed Peanuts Dry active

yeast Gelatin

Yellow cheese

Aspartame Salmon Buttermilk

Pumpkin seeds

Pork

http://wholefoodcatalog.info/nutrient/phenylalanine/confectioneries/low/

CONCLUSIONS:

PKU is a chronic disease that requires life-long treatment with a Phe controlled diet.

According to the Nelms text, a study comparing Phe concentrations to IQs demonstrated that for every 100umol/L increase in Phe above the target range IQ was decreased 1.3-3.1 points.

Proper nutrition is vital for people with this disease.

REFERENCES

Nelms M, Sucher K, Lacey K, Roth SL. Nutrition Therapy and Pathophysiology 2/e. United States: Wadsworth Cengage Learning; 2011, 2007.

Phenylketonuria [Internet]: Federal Government Website; c2012. Available from: http://ghr.nlm.nih.gov/condition/phenylketonuria

Birth to 36 months: Head circumference for age and Weight for length percentiles [internet]: National Center for Health Statistics; c2001. Available from: http://www.cdc.gov/growthcharts/data/set1clinical/cj41l020.pdf

> Nutrients > Phenylalanine > Confectioneries Low in Phenylalanine: WholeFoodCatalog; c2011. Available from: http://wholefoodcatalog.info/nutrient/phenylalanine/confectioneries/low/