Crea Creatinine assay Kit (Enzymatic method)

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.

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.

Principle

It involves 2 steps

Reagents preparation

Sample requirements

Serum, plasma and urine 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

Two-point calibration with purified water and CREA calibrator. Calibrators are sold separately, RANDOX or other traceable calibrators are recommended.

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 0.8-1.3 mg/dL; 70-115 μ mol/L

Female 0.5-0.9 mg/dL; 44-88μmol/L

Urine/First :

Male 40-278mg/dL; 3540~24600mmol

Morning urine Female 29-226mg/dL; 2550~20000mmol

Urine/24H:

Male 980-2200mg/24h;8600-19400μmol/24h

Female 720-1510mg/24h;6300-13400μmol/24h

Interferences/specificity

The following substances were tested for interference with this methodology. Criterion: Recovery within ±10 % of initial value.

Reagent blank absorbance

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

Sensitivity

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

Precision

Within-run : CV≤4%

Between-run: CV≤6%

Linearity range

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%.

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, 3^rd 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).