Technical Summary: Creatinine Analysis (Bulletin ref. TB119037)
 

A fast enzymatic analysis for plasma or serum Creatinine.
 

Name:
Code:
Size:

Creatinine
GMRD-170
2 x 20 tests (140 analyser cycles) The number of tests may be doubled by using half-volumes (micro-method).
 

Instruments:

All GM7 Series analysers
 

Principle:

i) Creatinine is hydrolysed to N-methylhydantoin and ammonia by creatinine iminohydrolase (CI) in a brief pre-reaction:
 

ii) The ammonia liberated in the above reaction forms L-glutamate with a-ketoglutarate in the presence of glutamate dehydrogenase (GLDH) and excess NADH:

iii) Under the conditions of the assay, the rate of oxidation of the excess NADH by peroxidase (POD) is inversely proportional to the creatinine concentration:

A sample blank allows for background interference by endogenous ammonia and other NADH consuming reactions.

Samples:
Sample volume:
Linearity:
Precision:
 

Plasma, serum, urine (diluted 1:50 - 1:100)
100 µl
750 µmol/L (8.5 mg/dl)
Typical within-run C.V. ± 10 µmol/L (3 % @ 88 µmol/L;
1.7 % @ 350 µmol/L)
 

Accuracy:

Method comparison vs Automated Jaffe (AU5000):
y (Analox) = 1.04x - 0.2 mg/dl, r = 0.990; n = 49
 

Reagent Stability:

Shelf-life 9 months unopened when stored at 0 - 5°C.
Reconstituted NADH/GLDH/a-ketoglutarate, 7 - 10 days (2 vials) when stored at 0 - 5°C.