To the Editor,
Glycated hemoglobin (HbA1C) is an accepted index of mean blood glucose [1]. It is formed by the non-enzymatic binding of circulating glucose to hemoglobin. Higher levels of glucose in the blood contribute to more binding and consequent higher levels of HbA1C [2].
In the laboratory, different investigations require blood collection with different additives. In case of HbA1C estimation most of the commercially available kits demand blood collection in EDTA tubes which often necessitates collection of additional blood. Considering this the present study was designed to determine the effect of common blood additives on HbA1C level (Table 1).
Table 1.
Effect of blood additives on HbA1C level (as % of total Hb)
| EDTA | Heparin | Citrate | Fluoride | |
|---|---|---|---|---|
| Normal Sample 1 | 5.6 | 5.6 | 5.6 | 5.6 |
| Normal Sample 2 | 5.5 | 5.6 | 5.5 | 5.5 |
| Normal Sample 3 | 5.9 | 5.9 | 5.8 | 5.9 |
| Normal Sample 4 | 5.6 | 5.7 | 5.6 | 5.6 |
| Diabetic Sample 1 | 10.1 | 10.1 | 10.2 | 10.1 |
| Diabetic Sample 2 | 9.7 | 9.6 | 9.6 | 9.6 |
Venous blood samples from four normal healthy males and two diabetic patients were collected in commercially available EDTA, sodium citrate, heparin and fluoride tubes (Agappe Diagnostics Ltd) as per the manufactures instructions. HbA1C was estimated after three hours of blood collection using BioRad D10 cation exchange HPLC analyzer.
No significant changes in the HbA1C values were observed between the samples taken in different tubes. The results revealed that lithium heparin, EDTA, sodium citrate and fluoride in the commercially available blood collection tubes do not affect HbA1C level, when tested within 3 h after collection. The results exclude the absolute necessity for blood collection in EDTA tubes for HbA1C estimation. Although the kits recommend the use of EDTA tubes, there is no harm in using other anticoagulants.
References
- 1.Rohlfing CL, Little RR, Madsen R, Harris MI, Flegal KM, Eberhaedt MS, Goldstein DE. Use of GHb (HbA1C) in screening for undiagnosed diabetes in the U.S. population. Diabetes Care. 2000;23(2):187–191. doi: 10.2337/diacare.23.2.187. [DOI] [PubMed] [Google Scholar]
- 2.Kilpatrick ES. Glycated haemoglobin in the year 2000. J Clin Pathol. 2000;53(5):335–339. doi: 10.1136/jcp.53.5.335. [DOI] [PMC free article] [PubMed] [Google Scholar]