Creatinine (Cr) Assay Kit – Bulk Reagents


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Selling unit: per 100ml

Product Name

Common name: Creatinine (Cr) assay kit (sarcosine oxidase method)

English name: Creatinine test reagent kit (Method of sarcosine Oxidase)

Reagent Ratio

3:1,4:1 are available, minimum package

Creatinine (Cr) assay kit

Intended Use

This kit is used for the in vitro determination of creatinine content in serum, plasma or urine.

Creatinine is formed in muscle from creatine phosphate by spontaneous and irreversible conversion, and the amount of creatinine formed is usually fairly constant unless there is a large change in muscle mass. Free creatinine is not reused in body metabolism but is mainly filtered through the glomerulus and subsequently excreted in the urine. The amount of creatinine circulating is therefore completely dependent on the rate of its excretion, and thus the measurement of creatinine in serum or plasma (usually performed together with a urea test) can be used to check kidney function as a diagnostic indicator of advanced kidney disease. An increase in creatinine is seen in chronic renal failure with reduced excretion or in acromegaly. The main clinical diagnostic methods of creatinine determination kit are picric acid method, creatinine deaminase method, creatine oxidase enzyme method, etc.

Test Principle

In the first step of the reaction, the endogenous creatine and sarcosine in the sample are eliminated with creatinase and sarcosine oxidase. In the second step of the reaction, creatinine in the sample is generated in the presence of creatinase to form creatine, which in turn generates hydrogen peroxide in the presence of creatinase and creatine oxidase, the latter forming a red quinonimine compound with 4-aminoantipyrine and TOOS by the action of oxidase, thus causing an increase in absorbance at 546 nm, such change being proportional to the concentration of creatinine in the sample.

Main Components

Reagent components included in the product.

Creatinine (Cr) assay kit

*Components are not interchangeable in kits with different lot numbers.

*Reagent components not included in the product, but necessary for the test: outsourced normal and abnormal QCs and calibrators.

Storage Conditions And Expiration Date

The kit is stored at 2-8°C away from light and is valid for one year.

Reagents that have been opened are taken care not to be contaminated and the reagents are stabilized in the instrument compartment (2-8°C) for one month.

The reagents must not be frozen.

Applicable Instruments

Hitachi 7180/7600; Olympus AU680/2700; Toshiba TBA120; Myriad BS2000M/480; Siemens ADVIA 1800/2400 series automatic biochemical analyzers.

Sample Request

  1. Fresh serum or plasma (heparin or EDTA anticoagulated). Serum samples are stable at room temperature for 7 days.
  2. 2. fresh urine, urine specimens were diluted 1:10 times with saline (or distilled water, deionized water).

Test Method

  1. Reagent preparation: liquid reagents are ready to use out of the bottle.
  2. test conditions: (different test instruments can be requested according to the different parameters on the machine)

Creatinine (Cr) assay kit

Operation steps.

Creatinine (Cr) assay kit

Reagents and sample volumes can be increased or decreased in proportion to the requirements of different biochemical analyzers.

  1. Calibration procedure.

Randox calibration sera are recommended. the method of choice for Randox calibration sera is the creatinine PAP method.

  1. QC control procedures.

It is recommended that each laboratory establish its own quality control system and select appropriate quality control products for quality control. The measured values of QC products should be within the specified range. If outside the specified range, it is necessary to take appropriate measures or contact the manufacturer.

  1. Calculation.

Creatinine content in sample (μmol/L) = (ΔA sample – ΔA blank) × C standard / (ΔA standard – ΔA blank)

Positive Judgment Value Or Reference Interval


Adult males: 59-104 μmol/L

Adult women: 45-84 μmol/L

Morning urine

Adult male: 3540-24600 μmol/L

Adult women: 2550-20,000 μmol/L

It is recommended that each laboratory establish its own reference range of normal values.

Interpretation Of Test Results

The determination of creatinine in serum, plasma or urine is only one of the indicators used by the clinician to make a diagnosis of the patient. The clinician must also make a comprehensive judgment based on the patient’s physical symptoms, medical history, and other diagnostic items and diagnostic tools.

Limitations Of The Test Method

Ascorbic acid ≤ 30 mg/dL, bilirubin ≤ 20 mg/dL, hemoglobin ≤ 250 mg/dL, and celiac disease ≤ 500 mg/dL did not interfere with the determination.

Product Performance Index

Absorbance of reagent blank: wavelength 548 nm, optical diameter 1.0 cm, temperature 37°C, A0  ≤ 0.15.

Analytical sensitivity: the kit tests 100 μmol/L of the test substance, the absorbance change value ΔA ≥ 0.03.

Linearity interval: test serum samples, reagent linearity in the interval of 10-9000 μmol/L, the linear correlation coefficient|r| should be not less than 0.990; in the interval of 10-70 μmol/L, the absolute deviation of linearity should not exceed 7 μmol/L; in the interval of (70- 9000 μmol/L, the relative deviation of linearity should not exceed ±10%.

Precision: repeatability CV ≤ 5%; relative extreme difference between batches ≤ 10%.

Accuracy: Relative deviation ≤ 10%.


  1. 1. This product is for in vitro diagnosis only.
  2. 2. Avoid contamination when using the reagent, the container used must be clean, and please take necessary precautions, do not swallow, and avoid contact with skin and mucous membrane.
  3. 3. Please dispose of the measured samples and waste liquids in accordance with the relevant national and local laws and regulations.
  4. 4. Do not mix R1 and R2 into a single reagent.
  5. 5. When changing the reagent lot number, please recalibrate.


  1. Newman DJ, Price CP. Renal function and nitrogen metabolites. in:Burtis CA, Ashwood ER, editors. tietz Textbook of Clinical Chemistry. 3rd ed. Philadelphia: W.B Saunders Company; 1999. p. 1204-.
  2. Thomas L. Clinical Laboratory Diagnostics. 1st ed. Frankfurt: TH-Books Verlagsgesellschaft; 1998. p. 366-74.
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