PRINCIPLE OF THE METHOD
The assay is based on the reaction of creatinine with sodium picrate as
described by Jaffé.
Creatinine reacts with alkaline picrate forming a red complex. The time
interval chosen for measurements avoids interferences from other serum
constituents.
The intensity of the color formed is proportional to the creatinine
concentration in the sample1.
CLINICAL SIGNIFICANCE
Creatinine is the result of the degradation of the creatine, component of
muscles, it can be transformed into ATP, that is a source of high energy for
the cells. The creatinine production depends on the modification of the
muscular mass, and it varies little and the levels usually are very stable.
Is excreted by the kidneys. With progressive renal insufficiency there is
retention in blood of urea, creatinine and uric acid.
Elevate creatinine level may be indicative of renal insufficiency1,2.
Clinical diagnosis should not be made on a single test result; it should
integrate clinical and other laboratory data.
STORAGE AND STABILITY
All the components of the kit are stable until the expiration date on the
label when stored tightly closed at 2-8ºC, protected from light and
contaminations prevented during their use.
Do not use reagents over the expiration date.
Signs of reagent deterioration:
- Presence of particles and turbidity.
- Blank absorbance (A) at 492 nm ≥ 1,80.
ADDITIONAL EQUIPMENT
- Spectrophotometer or colorimeter measuring at 492 nm (490-510).
- Matched cuvettes 1,0 cm light path.
- General laboratory equipment.
SAMPLES
- Serum or heparinized plasma1.
Creatinine stability: 24 hours at 2-8ºC.
- Urine (24 h): Dilute sample 1/50 with distilled water. Mix. Multiply results by
50 (dilution factor);
Creatinine stability: 7 days at 2-8ºC.
NOTES
1. CREATININE CAL: Proceed carefully with this product because due its
nature it can get contamined easily.
2. Calibration with the aqueous Standard may cause a systematic error in
automatic procedures. In these cases, it is recommended to use a serum
Calibrator.
3. Use clean disposable pipette tips for its dispensation.
4. SPINREACT has instruction sheets for several automatic analyzers.
