GA-X (Glycated albumin assay kit)

Storage

Up to the expiration date indicated on the label, when stored unopened at 2-8℃ and protected from light.

Once opened, the reagents are stable for 30 days when refrigerated on the analyzer or refrigerator. 

Contamination of the reagents must be avoided.

Do not freeze the reagents.

Once dissolved, the calibrator is stable for 7 days at 2-8℃, the control is stable for 7 days at 2-8℃, do not freeze.

Principle

1. Determination of glycated albumin

In the sample (serum), specific proteases are added to decompose Glycated albumin to form glycosylated amino acids. Then glycosylated amino acids are converted into glucoaldosterone, amino acids, and hydrogen peroxide by specific glycosylated amino acid oxidase. Under the action of peroxidase, hydrogen peroxide reacts with 4-amino-aminoantipyrine and TOOS to form red quinone-imine[3]. The concentration of glycated albumin in the sample was obtained by measuring its absorbance.

2. Determination of albumin

In pH 4.2, the albumin in the sample (serum) binds with the indicator bromocresol green to form a blue-green complex. The concentration of albumin in  the sample was obtained by measuring the change of absorbance.

3.Calculation of glycated albumin value (%)

Reagents

Sample requirements

1. Serum, heparin or EDTA plasma, and urine are suitable for samples. Whole blood, hemolysis is not recommended for use as a sample. Freshly drawn serum is the preferred specimen.

2. Stability: Serum/plasma: 7 days at 2-8℃;

Calibrator preparation

Carefully open the bottle, avoiding the loss of lyophilizate, and pipette in exactly 1.0 mL of distilled /deionized water. Carefully close the bottle and dissolve the contents completely by occasional gentle swirling within 30 minutes. Avoid the formation of foam. The dissolved calibrator can be used without any other pretreatment.

Quality control preparation

Carefully open the bottle, avoiding the loss of lyophilizate, and pipette in exactly 1.0 mL of distilled/deionized water. Carefully close the bottle and dissolve the contents completely by occasional gentle swirling within 30 minutes. Avoid the formation of foam. The dissolved control can be used without any other pretreatment.

Method

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

2. Measurement

1）GA：

ΔA = [(A2-A1) _sample]- [(A2-A1) _blank] 2）

ALB：

ΔA = [(A2-A1) _sample]- [(A2-A1) _blank]

Calibration

It is recommended to use the Calibrator from Hyasens and distilled/deionized water for two-point calibration. If the reagent changes the batch, recalibration should be performed.

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

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

Serum / Plasma: 10.8%~ 17. 1%

Interferences/specificity

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

Reagent blank absorbance

The Blank absorbance of the GA reagent should be ≤0.020; The Blank absorbance of the ALB reagent should be ≤0.35.

Analytical sensitivity

When the concentration of GA is 1.0 g/dL, the absorbance difference before and after the reaction should vary between 0.03 and 0.05; When the concentration of ALB is 4.11 g/dL, the absorbance difference before and after the reaction should not be less than 0.2;

Precision

Within-run: CV≤5%

Between-run: CV≤10%

Linearity range

Conventional Units:

GA/ALB: 7.0%~70.0%

The concentration of the test sample should be within the linear range. If the value of sample exceeds 70.0%(GA/ALB), the sample should be diluted with 9 g/L NaCl solution.

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] Guide for clinical application of blood glucose monitoring in China (2011 edition). Chinese Journal of Diabetes，2011, 3(1): 13 -21.

[2] Santiago Rodriguez-Segade et al. Progression of nephropathy in type 2 diabetes: The glycation gap is a significant predictor after adjustment for glycohemoglobin (HbA1c). Clinical Chemistry, 2011, 57(2):264-271.

[3] M. Koga, et al. Glycated albumin and glycated hemoglobin are influenced differently by endogenous insulin secretion in patients with type 2 diabetes. Diabetes care, 2010, 33(2): 270– 272.