Accuracy of filter paper method for measuring glycated hemoglobin

Area of Science:

• Clinical Chemistry
• Endocrinology
• Diabetes Mellitus Research

Background:

• Glycated hemoglobin (HbA1c) is crucial for monitoring glycemic control in diabetes.
• Current HbA1c measurement requires inconvenient venipuncture and sample handling.
• Alternative, less invasive methods are needed for routine HbA1c assessment.

Purpose of the Study:

• To evaluate the feasibility of using dried capillary blood spots for HbA1c estimation.
• To assess the stability of HbA1c in dried blood spots at room temperature.
• To compare HbA1c values from dried capillary blood spots with those from venous blood samples.

Main Methods:

• Collected venous blood samples from 78 patients with type 1 or type 2 diabetes.
• Assessed HbA1c stability in capillary blood spots on filter paper stored at room temperature for 10 days.
• Compared HbA1c values from dried capillary blood spots with venous samples using Turbidimetric Inhibition Immunoassay.

Main Results:

• HbA1c remained stable in dried capillary blood spots for up to 10 days at room temperature.
• Dried blood spot HbA1c values showed an inherent variability within acceptable quality control limits (+/- 15%).
• A strong correlation (r=0.889, p<0.01) was observed between dried blood spot and venous HbA1c values, with a derived regression equation.

Conclusions:

• Dried blood spot analysis provides reliable and reproducible glycated hemoglobin measurements.
• Capillary sample HbA1c values were approximately 12% higher than venous samples.
• Adjusted normal ranges may be necessary for interpreting HbA1c results from dried blood spots.