RENAL FUNCTION TEST

DR. MD. MAHBUBUR RAHMAN MBBS, M. Phil , MBT (New Delhi)

DEPT. OF BIOCHEMISTRY

RAJSHAHI MEDICAL COLLEGE

NEPHRON

• STRUCTURAL UNIT OF KIDNEY.

NEPHRON

Definition of Renal Function test

The group of test by which we can assess the

function of kidney is known as Renal Function Test.

Function of kidney

• Formation of urine

• Maintenance of water balance

• Maintenance of electrolyte balance

• Maintenance of acid base balance

• Excreation of waste product e.g. Urea., uric acid

• Endocrine function e.g. Erythropoietin, vit –D3

• Maintenance of osmotic balance

FUNCTION OF KIDNEY

Regulation of water, electrolyte & acid-base

balance.

Excretion of the products of protein and nucleic

acid metabolism e.g. urea, creatinine, creatine ,uric

acid, sulphate, and phosphate.

water and electrolyte distribution

RENAL FUNCTION TEST

• It is convenient to discuss renal function in

terms of the assessment of glomerular and

tubular function

RENAL FUNCTION TEST

1. Test of glomerular function

2. Test of tubular function.

TEST OF GLOMERULAR FUNCTION

Clearence : This is the volume of plasma which

would be completely ‘cleared’ of the substance in

the time specified to give the amount seen in

urine.

U X V

• volume of plasma=

P

• U =Urine concentration of creatinine P =Serum or Plasma concentration of creatinine V = Volume of urine

2. Serum creatinine & urea mesurment

Normal value of serum creatinine

male: 60-130µmol/L(0.7-1.4 mg/dl)

Female: 40-60µmol/L(0.4-1.2mg/dl)

Normal value of serum urea

Adults: 3.3-7.7mmol/L(20-50mg/dl)

Infants: 1.3-5.8mmol/L(8-35mg/dl)

serum creatinine is better than

serum urea because---- Creatinine is

derived from muscle creatine

serum urea level is altered by dietary

protein, tissue breakdown,

hemorrhage, dehydration.

Cystatin C is a low-molecular-weight protein, the

serum concentrations of which, like creatinine,

correlate inversely with GFR..

3. Cystatin C measurement

Unlike creatinine, the concentration of cystatin

C is independent of weight and height, muscle

mass, age (>1year) or sex and is largely

unaffected by intake of meat or non-meat-

containing foods

Benefit of Cystatin C measurement

Proteinuria:

• Passes of protein more than 300 mg/day is called

proteinuria.

• Normal level of protein or albumin passes through

urine (less than 150mg/day of protein or 30

mg/day of albumin)

Normal level protein in urine 150-200 mg/day.

Cause of proteinuria

• Nephrotic syndrom

• Chronic glomerulonephritis

• Toxaemia of pregnancy

• Severe lower urinary tract infection

• Pyogenic or tuberculous pyelonephritis

• Diabetic nephropathy

• Hypertension

MICROALBUMINURIA

Albumin excretion in the range 25-300mg/day

is termed microalbuminuria

Test of tubular function

Osmolarity mesurments in the plasma and urine & there

ratio.[Normal1-3]

Specific proteinuria: β2 microglobulin α2 microglobulin

3. Measurement of serum electrolyte

Glycosuria

Aminoaciduria