Filter Paper-Dried Blood Spot Assay of Hemoglobin A1c.

Background: The objective of this study was to assess the feasibility of using blood spots collected by finger sticks and dried on filter paper for measuring Hemoglobin A1c (HbA1c) by a new method to assess long term glycemic control. Blood spots offer advantages of short collection time, low invasiveness, reduction of sample volume, ability to obtain repeated measures and ease of sample storage. Methods: Forty subjects contributed a blood spot sample from a finger stick and a blood sample through venipuncture. The blood spots obtained from finger sticks on a filter paper were air-dried for 4 hours at room temperature after collection. Using an automated dried blood spot (DBS) puncher, 6.0 mm blood disks were obtained for testing and rehydrated in assay buffer. All samples were tested in parallel. Samples were evaluated for the presence of HbA1C using conventional commercial kits based on an immuno-turbidimetric assay in whole blood modified for use in dried blood spots. Results: A positive correlation (R²= 0.93) was found in HbA1c levels from the blood spot and whole blood samples. The HbA1c levels obtained from blood spots (5.41 ± 1.06%; Assay range 3.36%- 12.02%) were similar to those derived from whole blood samples (5.44 ± 1.68%; Assay range 4.92%-12.29%). The extracted samples showed good stability for 8 days when stored at 4°C. The between assay CV ranged between 5.25%- 14.79% and the within run variation was between 4.28%- 10.33%. Conclusion: We conclude that in our assay, HbA1c levels obtained from blood spot samples correlate well with values obtained from standard whole blood assays. The design of the assay and nature of the samples also make this method suitable for screening programs that consist of self-sampling for better management of chronic glycemia and its complications. [ABSTRACT FROM AUTHOR]