Accuracy of Laboratory Parameters

in Management of CKD.

College of Medical Laboratory Science, Sri Lanka

Direct Methods of

Nutritional Assessment

• Anthropometric methods

• Medical Laboratory methods

• Clinical methods

• Dietary evaluation methods

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CKD Risk Factors

Modifiable

• Diabetes

• Hypertension

• History of AKI

• Frequent NSAID use

Non-Modifiable

• Family history of kidney disease, diabetes, or hypertension

• Age 60 or older (GFR declines normally with age)

• Race/U.S. ethnic minority status

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Types of Assays

• Static assays: measures the actual level of

the component in the specimen (serum

iron, Serum electrolytes)

• Functional Assays: measure a

biochemical or physiological activity that

depends on the component of interest (eg:

Glycated haemoglobin, Creatinine)

• Functional assays are not always specific

to the component

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Target

• Accuracy

• Precision

• Accuracy

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• Detect renal

damage

• Monitor functional

damage

• Help determine

etiology

Categories of renal function tests

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• glomerular filtration

rate=GFR

• plasma creatinine= Pcr

• plasma urea-Purea

• urine volume= V

• urine urea- Uurea

• cystatin C in plasma?

• urine protein

• urine glucose

• hematuria

• Osmolality

• Electrolytes

Tests of renal function

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Tests of Glomerular Filtration Rate

• Urea

• Creatinine

• Creatinine Clearance

• eGFR

• Cystatin C

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GFR & Creatinine

• Ideal Marker

• Produced normally by the body

• Produced at a constant rate

• Filtered across glomerular membrane

• Removed from the body only by the

kidney filtered only, not reabsorbed or

secreted

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Interference

• Pre Analytical phase

• Analytical Phase

• Post Analytical Phase

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Interfering factors for elevated S. Creatinine

• Destruction of muscle

• High dietary intake of meat

• Hypothyroidism

• higher average muscle mass (Eg Afro-Caribbean)

• increase in musculature (Eg. Bodybuilding

• Drugs

• Some Cephalosporins

Interference with alkaline picrate assay

• Corticosteroids and vitamin D metabolites

Modify the production rate & the release of creatinine

• Artifactual (Eg. Diabetic Ketoacidosis) CMLS.SL 11

Interfering factors for Reduced S. Creatinine

• Increasing age

Age-related decline in muscle mass

• Females - reduced muscle mass

• Malnutrition/ muscle wasting / amputation

Reduced muscle mass ± reduced protein intake

• Vegetarian diet

• Dehydration

• Hyperthyroidism

• Icteric Serum Specimens

Eg: Due to elevated Bilirubin

• Drugs - Testosterone therapy

Eg: Cimetidine, Trimethoprim, Sulphamethoxazole, Fibric acid D

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Patient Preparation for S. Creatinine

• No Specific patient preparation

• Dose adjustment or stop taking some interfering drugs on clinicians advice

• Nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen

• Chemotherapy drugs

• Cephalosporin

• Cimetidine

• Interpret results with related to drug history

Reference Range – S. Creatinine

Male

Infant - Not established

Age 1-2 years - 0.1–0.4 mg/dL

Age 3-4 years - 0.1–0.5 mg/dL

Age 5-9 years - 0.2-0.6 mg/dL

Age 10-11 years - 0.3-0.7 mg/dL

Age 12-13 years - 0.4-0.8 mg/dL

Age 14-15 years - 0.5-0.9 mg/dL

Age 16 years or older - 0.8-1.3 mg/dL

Female

Infant - Not established

Age 1-3 years - 0.1–0.4 mg/dL

Age 4-5 years - 0.2–0.5 mg/dL

Age 6-8 years - 0.3-0.6 mg/dL

Age 9-15 years - 0.4-0.7 mg/dL

Age 16 years or older - 0.6-1.1 mg/dL

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Serum Creatinine Concentration

• Normally 0.7-1.4 mg/dl, depending on

muscle mass

• Inversely proportional to GFR

• Good way to follow changes in GFR

• BUT also elevated by muscle mass,

tubular secretion

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Tests that predict kidney disease

• eGFR

• Albumin Creatinine Ratio

(ACR or Microalbumin)

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Kidney

damage and normal or GFR

Kidney

damage and

mild

GFR

Severe

GFR

Kidney

failure

Moderate

GFR

Stage 1 Stage 2 Stage 3 Stage 4 Stage 5

Nephrologist Primary Care Practitioner

GFR 90 60 30 15

Who Should be Involved in the Patient Safety Approach to CKD?

Patient safety

Consult?

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Alternatives of identifying

CKD Stage 1

• Higher than normal levels of creatinine or urea

in the blood

• Blood or protein in the urine

• Evidence of kidney damage in an MRI, CT

scan, ultrasound or contrast X-ray

• A family history of polycystic kidney disease

(PKD)

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Assessment of component of interest

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Patients

Client

Healthy

Risk Group

Patient

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Diversity of Health Care Receivers

Clinicians

Lab Professionals

Clinicians

Nutritionists

Clinicians

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Traditional Health care Flow

Clinicians

Lab Professionals

Nutritionist

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Model for CKD/NCD control

Co-Management Model

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Future Approach

• Can serum creatinine be made more

sensitive by adding more information?

• Does it required an easy test to screen risk

group in GFR that can apply at risk

populations

• Can we assure patient centered health care

service with novel collaborative co

management model

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Thank you

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