Creatinine is an anhydride of creatine. It is formed in the muscle from creatine phosphate by an irreversible, non-enzymatic dehydration and loss of phosphate. Serum creatinine (a blood measurement) is an important indicator of renal health because it is an easily measured byproduct of muscle metabolism that is excreted unchanged by the kidneys
METHOD: Folin’s Method (Jaffe’s Reaction)
Creatinine reacts with picric acid in alkalme solution, With the formation of a red tautomer of creatinine picrate (Jaffe’s Reaction). The intensity of the colour developed is proportional to the amount of creatinine in the urine.
- 10% NaOH solution,
- 1% Picric Acid,
- Creatinine Standard Solution (1mg/ml) PROCEDURE:
- Label THREE 100 ml volumetric flasks as Unknown (U), Standard (S) and Blank (B).
- Transfer 1ml urine into flask ‘U’ , 1ml Creatinine Standard solution into flask ‘S’ and 1ml distilled water into flask ‘B’ respectively.
- To each flask add 20ml of Picric acid solution and 1.5ml of 10% NaOH solution. Mix well and allow to stand for 25 minutes at room temperature.
- Now dilute the contents of each flask to 100ml mark with distilled water and mix thoroughly.
- Read the Optical Density at 520nm in a photoelectric colorimeter.
Optical Density of Unknown (U) = ODu
Optical Density of Standard (S) = ODs
Concentration of Standard Solution = Cs Volume of Urine Used. V
URINARY CREATININE (gm/day) = ODU ×Cs/ODS × 1500/V × 1000
NORMAL RANGE: Urinary Creatinine = 1.0-1.8 gm/day.
The urinary excretion of creatinine does not Vary from day to day in a normal individual but it remains remarkably constant. Creatinine excretion 18 Independent. of diet and 1s not influenced by exercise. Creatinine appears to be entirely a waste product, unutilizable by the body. Even if ingested in diet or injected, it is almost, if not entirely, quantitatlvely excreted from the body. Muscular Dystrophy (Early Stage), Muscular Dystrophy (Late Stage), Due to increased tissue catabolism Muscular Atrophy, as in fever, Muscular weakness, Heavy meat diet. Paralysis.