Accuracy of Laboratory Parameters in Management of CKD.

College of Medical Laboratory Science, Sri LankaCollege 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

ModifiableModifiable

•DiabetesDiabetes

•HypertensionHypertension

•History of AKIHistory of AKI

•Frequent NSAID useFrequent 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 Static assays: measures the actual level of

the component in the specimen (serum the component in the specimen (serum iron, Serum electrolytes)iron, Serum electrolytes)

• Functional Assays: measure a Functional Assays: measure a biochemical or physiological activity that biochemical or physiological activity that depends on the component of interest (eg: depends on the component of interest (eg: Glycated haemoglobin, Creatinine)Glycated haemoglobin, Creatinine)

• Functional assays are not always specific Functional assays are not always specific to the component to the component

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Target

• AccuracyAccuracy

• PrecisionPrecision

• AccuracyAccuracy

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• Detect renal Detect renal damagedamage

• Monitor functional Monitor functional damagedamage

• Help determine Help determine etiologyetiology

Categories of renal function tests

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• glomerular filtration glomerular filtration rate=GFRrate=GFR

• plasma creatinine= Pplasma creatinine= Pcrcr

• plasma urea-Pplasma urea-Pureaurea

• urine volume= Vurine volume= V

• urine urea- Uurine urea- Uureaurea

• cystatin C in plasma?cystatin C in plasma?

• urine proteinurine protein• urine glucoseurine glucose• hematuriahematuria• OsmolalityOsmolality• ElectrolytesElectrolytes

Tests of renal function

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Tests of Glomerular Filtration Rate

• UreaUrea

• CreatinineCreatinine

• Creatinine ClearanceCreatinine Clearance

• eGFReGFR

• Cystatin CCystatin C

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GFR & Creatinine

• Ideal MarkerIdeal Marker

• Produced normally by the bodyProduced normally by the body

• Produced at a constant rate Produced at a constant rate

• Filtered across glomerular membraneFiltered across glomerular membrane

• Removed from the body only by the Removed from the body only by the kidney filtered only, not reabsorbed or kidney filtered only, not reabsorbed or secretedsecreted

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Interference

• Pre Analytical phasePre Analytical phase

• Analytical PhaseAnalytical Phase

• Post Analytical PhasePost Analytical Phase

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Interfering factors for elevated S. Creatinine• Destruction of muscleDestruction of muscle• High dietary intake of meatHigh dietary intake of meat• HypothyroidismHypothyroidism• higher average muscle mass higher average muscle mass (Eg Afro-Caribbean)(Eg Afro-Caribbean)

• increase in musculature increase in musculature (Eg. Bodybuilding(Eg. Bodybuilding

• DrugsDrugs• Some Cephalosporins Some Cephalosporins

Interference with alkaline picrate assay Interference with alkaline picrate assay

• Corticosteroids and vitamin D metabolites Corticosteroids and vitamin D metabolites Modify the production rate & the release of creatinine Modify the production rate & the release of creatinine

• Artifactual (Artifactual (Eg. Diabetic Ketoacidosis)Eg. Diabetic Ketoacidosis)

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Interfering factors for Reduced S. Creatinine

• Increasing age Increasing age Age-related decline in muscle massAge-related decline in muscle mass

• Females - reduced muscle massFemales - reduced muscle mass• Malnutrition/ muscle wasting / amputationMalnutrition/ muscle wasting / amputation

Reduced muscle mass ± reduced protein intakeReduced muscle mass ± reduced protein intake

• Vegetarian dietVegetarian diet• DehydrationDehydration• HyperthyroidismHyperthyroidism• Icteric Serum SpecimensIcteric Serum Specimens

Eg: Due to elevated BilirubinEg: Due to elevated Bilirubin• Drugs - Drugs - Testosterone therapyTestosterone therapy

Eg: Cimetidine, Trimethoprim, Sulphamethoxazole, Fibric acid D Eg: Cimetidine, Trimethoprim, Sulphamethoxazole, Fibric acid D

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Patient Preparation for S. Creatinine

• No Specific patient preparationNo Specific patient preparation• Dose adjustment or stop taking some interfering Dose adjustment or stop taking some interfering

drugs on clinicians advicedrugs on clinicians advice• Nonsteroidal anti-inflammatory drugs Nonsteroidal anti-inflammatory drugs

(NSAIDs), such as aspirin or ibuprofen(NSAIDs), such as aspirin or ibuprofen• Chemotherapy drugsChemotherapy drugs• CephalosporinCephalosporin• CimetidineCimetidine

• Interpret results with related to drug history Interpret results with related to drug history

Reference Range – S. Creatinine

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Serum Creatinine Concentration

• Normally 0.7-1.4 mg/dl, depending on Normally 0.7-1.4 mg/dl, depending on muscle massmuscle mass

• Inversely proportional to GFRInversely proportional to GFR

• Good way to follow Good way to follow changeschanges in GFR in GFR

• BUT also elevated by BUT also elevated by ↑↑ muscle mass, muscle mass, ↓↓ tubular secretion tubular secretion

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Tests that predict kidney disease

• eGFReGFR

• Albumin Creatinine RatioAlbumin Creatinine Ratio

(ACR or Microalbumin)(ACR or Microalbumin)

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Kidneydamage and

normal or ↑ GFR

Kidneydamage and

mild ↓ GFR

Severe↓ GFR

Kidneyfailure

Moderate ↓ GFR

Stage 1 Stage 2 Stage 3 Stage 4 Stage 5

NephrologistPrimary 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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Diversity of Health Care Receivers

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Traditional Health care Flow

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Model for CKD/NCD control

Co-Management Model

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Future Approach• Can serum creatinine be made more Can serum creatinine be made more

sensitive by adding more information?sensitive by adding more information?

• Does it required an easy test to screen risk Does it required an easy test to screen risk group in GFR that can apply at risk group in GFR that can apply at risk populationspopulations

• Can we assure patient centered health care Can we assure patient centered health care service with novel collaborative co service with novel collaborative co management model management model

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Thank you

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