Complement C4 (C4) Assay Kit – Bulk Reagents


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Selling unit: per 100ml

Product Name

  1. Common name: Complement C4 (C4) test kit (immunoturbidimetric assay)
  2. English name: C4 Reagent Kit (Immunoturbidimetric Method)

Reagent Ratio

3:1, 4:1, 5:1, common ratio 3:1, other ratios need to be customized

Intended Use

This reagent is used to determine the content of C4 in human serum and plasma.

Complement is mainly synthesized in the liver, and complement C3 and C4 are the most frequently measured components of the classical activation pathway of complement, and its determination is useful in the diagnosis and treatment of autoimmune diseases such as SLE. In SLE, the decrease in C4 often precedes the other complement components and is later to rebound in remission than the other components. Elevated C4 levels are common in the acute phase of rheumatic fever, periarteritis nodosa, dermatomyositis, myocardial infarction, Rditer’s syndrome, and various types of polyarthritis.

Test Principle

C4 and its corresponding antibody meet in the liquid phase and form an insoluble immune complex, causing turbidity in the reaction solution, and the level of turbidity reflects the amount of C4 in the serum sample.

Main Components

Reagent components included in the product.

Complement C4 (C4) Assay Kit & Bulk Reagents

*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 careful not to be contaminated, and reagents are stable 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

Plasma anticoagulated with serum or heparin or EDTA should be separated within 2 hours after blood collection and stored at room temperature (15-25°C) for 2 days and 2-8°C for 2 days.

Test Method

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

Complement C4 (C4) Assay Kit & Bulk Reagents

Operation steps.

Complement C4 (C4) Assay Kit & Bulk Reagents

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

  1. Calibration procedure.

Landau calibrators are recommended.

  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.

5 points are calibrated and the corresponding values are entered. With △A as the vertical coordinate and concentration as the horizontal coordinate, the standard curve is plotted, and this standard curve is corrected by the non-linear method Spline, Logit-Log4P and other modes, and this standard curve is saved and used to calculate the results.

Positive Judgment Value Or Reference Interval

0.1 to 0.4 g/L (10 to 40 mg/dL)

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

Interpretation Of Test Results

Bilirubin ≤ 40 mg/dL, hemoglobin ≤ 500 mg/dL and celiac ≤ 500 mg/dL did not interfere with the determination.

Limitations Of The Test Method

The determination of C4 in human serum or plasma 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.

Product Performance Index

Absorbance of reagent blank: wavelength 340 nm, optical diameter 1.0 cm, temperature 37°C, A0  ≤ 0. 15.

Analytical sensitivity: The kit tests 0.4g/L of the analyte, the absorbance change value ΔA ≥ 0.04.

Linearity range: test serum samples, reagent linearity in the interval of 1.5~120 mg/dL, linear correlation coefficient|r| should not be less than 0.975; in the interval of 1.5~30.0 mg/dL, the absolute deviation of linearity should not exceed 3 mg/dL; in the interval of (30.0~120 mg/dL, the relative deviation of linearity should not exceed ±10%.

Precision: repeatability CV≤ 10.0%; relative extreme difference between batches≤ 15.0%.

Accuracy: Relative deviation ≤ 10%.


  1. This product is for in vitro diagnosis only.
  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. Please dispose of the measured samples and waste liquids in accordance with the relevant national and local laws and regulations.
  4. Please dispose of the measured samples and waste liquids according to the relevant national and local laws and regulations.
  5. When changing the reagent lot number, the calibration should be re-calibrated.


  1. Karl J. Engel WD. Determination of Apolipoprotein AI and B without sample dilution. poster presented at the 57thmeeting of the European Atherosclerosis Society, Lisbon and the IX European Congress of Clinical Chemistry, Cracow (1991).
  2. Burtis CA, Ashwood ER. Tietz Fund. of Clin. Chem. 5thed. 30-54, 335-336, 462-494 and 972-973.
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