Renal Function Lab

Question 1

How is creatinine in serum measured

Answer 1

Using Jaffe method

Question 2

Principle of Jaffe method

Answer 2

Creatinine + picrate - orange colour (in alkaline medium)

Can be measured at 505 nm

Question 3

Normal serum creatinine levels

Answer 3

Male: 116-174 umol/L
Female: 56-85 umol/L

Question 4

Creatinine clearance formula

Answer 4

U.V/P ➗ 1440 (U = urine conc, P = plasma conc, V = volume of urine)

Question 5

Name 5 methods for urine protein estimation

Answer 5

Biuret method 
Lowry method 
Bradford method
Ultraviolet absorption 
Kjedahl method

Question 6

What does Biuret reagent contain

Answer 6

Sodium (or potassium) hydroxide
Hydrated copper (II) sulfate
Potassium sodium tartrate

Question 7

Using biruet method what does the colour coordination form a complex between

Answer 7

Cu2+ ion and carbonyl oxygen and amide nitrogen of the peptide bond

Question 8

Principle of biuret method

Answer 8

Determines presence of peptide bonds.

Peptide structure with at least 2 peptide links produces a violet colour when with alkaline copper sulfate.

Question 9

Why can blue coloured copper II ion form a complex with peptide bonds

Answer 9

Peptide has unshared electron pairs in nitrogen and oxygen of water.

Question 10

Purpose of sodium hydroxide in biuret solution

Answer 10

Provides alkaline medium

Question 11

Purpose of potassium sodium tartrate in biuret solution

Answer 11

Chelates and stabilises the cupric ions to maintain solubility in alkaline solution

Question 12

Normal protein in adult urine

Answer 12

60-80 g/L

Question 13

Normal serum urea concentration

Answer 13

1.7-8.4 umol/L

Question 14

What is low gfr indicative of

Answer 14

Kidney disease

Question 15

What is elevated urea and creatinine levels indicative of

Answer 15

Acute renal failure

Question 16

What is pyelonephritis

Answer 16

Inflammation of the kidney

Question 17

Name a variable factor for serum creatinine levels

Answer 17

Depending on muscle mass.

Creatinine is an end product of muscle metabolism

Question 18

Creatinine clearance satisfactory rate

Answer 18

90 ml/min or above

Question 19

What could be indicative of tubular dysfunction

Answer 19

Presence of B2 microglobulin in urine

Question 20

Tests for glomerular function

Answer 20

Serum urea
Serum creatinine
Clearance tests
eGFR

Question 21

Tests for tubular function

Answer 21

Acidification test
Osmolality
Urine concentration test

Question 22

What is urea

Answer 22

Principal nitrogenous end product of protein and amino acid catabolism.

Question 23

Tests used for detecting urea

Answer 23

Nesseler’s reaction
Bertholot reaction
Kinetic method

Question 24

Principle of urea assay

Answer 24

Measure nitrogen content of urea (BUN - blood urea nitrogen)

Enzyme urease and glutamate dehydrogenase (GLDH) used

Question 25

Why is whole blood not considered an ideal specimen for creatinine concentration

Answer 25

Contains many noncreatinine chromogens

Question 26

Name jaffe-positive substances (other than creatinine)

Answer 26

Acetoacetic acid
Pyruvic acid
Hydantoin

Question 27

Modifications to jaffe method that eliminate interferences from other jaffe-positive substances

Answer 27

• measure absorbance at two different pH levels. Acidification eliminates colour produced by creatinine and not interfering substances
• Automated analysers take readings at selected time intervals to avoid interference of non creatinine chromogens because noncreatinine chromogens produce colour at slower/faster rates.

Question 28

Ratio of urea:creatinine

Answer 28

between 10:1 and 20:1

Question 29

Plasma filtration rate by glomeruli

Answer 29

140 ml/min

Question 30

What test is the gold standard for renal clearance

Answer 30

Inulin clearance