Creatinine assay kit (Enzymatic method, Calcium antidobesilate)

In vitro test for the quantitative determination of creatinine (Crea) concentration in serum, plasma and urine on photometric systems. Creatinine measurements are used in the diagnosis and treatment of renal diseases, in monitoring renal dialysis, and as a calculation basis for measuring other urine analytes.

Principle

It involves 2 steps

Sample requirements

Serum and plasma are suitable for samples. Whole blood and hemolysis are not recommended for use as a sample. Freshly drawn serum is preferred specimen.

Method

1. Reagent preparation：Liquid reagent can be used when opened

2. Measurement

△A=[（A2-A1）sample / calibrator]-[（A2-A1）blank]

Calibration

It is recommended to use the Calibrator from RANDOX and distilled/deionized water for two-point calibration.

Calibration frequency:

After reagent lot changed. As required following quality control procedures.

Quality control

At least two levels of control material should be analyzed with each batch of samples.Each laboratory should establish its own internal quality control scheme and procedures for corrective action if controls do not recover within the acceptable tolerances.

Reference intervals[1,2]

Each laboratory should establish its own reference intervals based upon its patient population. The reference intervals measured at 37℃ listed below were taken from literature: 

Serum/Plasma:

Male: 53-123μmol/L

Female : 44-106μmol/L

Urine:

Male :7.1~17.1mmol/24h

Female: 5.3~15.9mmol/24h

Interferences/specificity

The following substances were tested for interference with this methodology. Criterion:

Recovery within ±10 % of initial value.

* NSI: No Significant Interference (within ± 10 %)

Storage and stability

Up to expiration date indicated on the label, when stored unopened at 2-8℃ and protected from light. Once opened, the reagents are stable for 28 days when refrigerated on the analyzer or refrigerator. Contamination of the reagents must be avoided. Do not freeze the reagents. Once dissolved, the calibrator are stable for 7 days at 2-8℃, the control are stable for 7 days at 2-8℃，do not freeze.

Reagent blank absorbance

The absorbance of reagent blank at 546 nm should be <0.3 A.

Precision

Within-run : CV≤5%

Between-run: CV≤6%

Linearity range

Sample Type: Serum / Plasma

Conventional Units: 20-2000μmol/L

1) In the range of 20-2000μmol/L, the correlation coefficient r should not be less than 0.990;

2) In the range of [20-70] μmol/L, the absolute deviation between the measured concentration and the estimated value should be within the range of ±7 μmol/L; (in the range of 70-2000] μmol/L, the relative deviation between the measured concentration and the estimated value should be not more than ±10%.

Analytical sensitivity

When testing 100 μmol/L creatinine, the absolute value of the absorbance difference should not be less than 0.01.

Stability

All dosage forms of reagents can be used before the expiration date indicated on the label under the conditions of being protected from light and stored at 2~8°C; the reagents can be stable for 30 days after the bottle is opened.

Warnings and precautions

1.For in vitro diagnostic use.

2.Take the necessary precautions for the use of laboratory reagents.

3.Preservative contained. Do not swallow. Avoid contact with skin and mucous membranes.

4.Disposal of all waste material should be in accordance with local guidelines.

5.Material safety data sheet is available on request for professional users.

References

[1] Tietz Textbook of Clinical Chemistry, 3rd edition. Burtis CA, Ashwood ER. WB Saunders Co., 1999.

[2] Heinegard, D., Tiderstrom, G., Clin. Chem. Acta, 43:305 310 (1973).

[3] National Committee for Clinical Laboratory Standards, How to Define,Determine, and Utilize Reference Intervals in the Clinical Laboratory, Approved Guideline, CLSI publication C28-A, Villanova, PA(1995).