RENAL FUNCTION TESTS

Dr Vijay Marakala M.D.

BIOCHEMISTRYSIMS&RC

Formation of urine as the

waste product

Excretion of NPN

substances

Regulation of salt & water

balance

Regulation of acid-base balance

Production of Hormones

Functions of KIDNEY

Assessment of the extent of renal

damage

Monitoring the progression of renal

damage

Monitoring and adjusting the dose of renal toxic drugs

Renal Function Tests –required for……

Renal blood flow

GFR

Renal glomeruli function

Renal tubular function

Urinary output

RFTs give information regarding…….

Classification of RFTs1. Urine analysis

2. Tests for assessment of glomerular function

3. Tests to measure renal plasma flow

4. Tests for assessment of tubular function

1. URINE ANALYSIS

Physical examination

Chemical examination

Microscopic examination

2. Tests for assessment of glomerular function

Renal clearance test

Blood urea and serum

creatinine

Proteinuria Haematuria

RFT

Renal Clearance Test

Renal clearance of a substance is defined as the volume of plasma from which the substance is completely cleared by the kidneys per minute

What is meant by clearance test?

Renal Clearance Test

• Endogenous creatinine and urea• Exogenous inulin

Substances used for clearance test

Renal clearance test used to assess the rate of glomerular filtration and renal blood flow

Creatinine

• Based on the rate of excretion by the kidneys of metabolically produced creatinine

Creatinine clearance test

Creatinine is freely filtered at the

glomerulus and is not reabsorbed by

the tubules

Creatinine

Normal

↓Creatinine clearance

90-120ml/min

↓GFR

Creatinine clearance test

Normal

Sensitivity of the test is

less

75ml/min

40% filtered urea is

reabsorbed

Urea clearance test

Normal

Method of choice for determination

of GFR

120ml/min

Freely filtered & neither reabsorbed

nor secreted by tubules

Inulin clearance test

2. Tests for assessment of glomerular function

Renal clearance test

Blood urea and serum creatinine

Proteinuria Haematuria

RFT

Blood urea and serum creatinine

Blood urea 20-40mg/dl

S. creatinine 0.6-1.2mg/dl

2. Tests for assessment of glomerular function

Renal clearance test

Blood urea and serum

creatinine

Proteinuria Haematuria

RFT

Proteinuria

• Proteinuria in urine is an indicator of leaky glomeruli

• 30-300mg/day is called microalbuminuria• Microalbuminuria is the earliest sign of renal

damage

Small amount of protein usually less than 30mg/day, is found in urine

2. Tests for assessment of glomerular function

Renal clearance test

Blood urea and serum

creatinine

Proteinuria Haematuria

RFT

Haematuria

Intact glomerulus does not allow the passage of RBC.

Glomerular damage, RBC leakage occurs

Tests for Tubular Function

Urine concentration test

Urine dilution test

Specific proteinuria or Tubular proteinuria

Glycosuria

Amino aciduria