CAPILLARY BLOOD ON FILTER-PAPER FOR DETERMINATION OF HBA(1C) BY ION-EXCHANGE CHROMATOGRAPHY

OBJECTIVE - To facilitate HbA(1c) determination, we evaluated an HbA(1 c) filter paper system enabling capillary blood sampling at home by th e patients. RESEARCH DESIGN AND METHODS - Capillary blood (two drops) was applied to a filter paper (HbA(1c) Via Post) and sent to the labor atory where a small disc was punched out on the filler paper. Hemoglob in was eluted from the disc in a buffer containing cysteine to elimina te the interfering glutathione adduct (HbA,) Formed during storage. An alysis was performed by ion-exchange chromatography (Mono S, high-perf ormance liquid chromatography), and the eluate was compared with hemol ysate of venous blood From 41 patients. The stability of blood impregn ated on filter paper was checked at different temperatures over differ ent periods of time. RESULTS - There was an excellent agreement (r = 0 .99) between HbA(1c) values from capillary blood on filter paper and H bA(1c) values from venous blood. HbA(1c) values were constant when sto red on filter paper For 5-7 days at 20-21 degrees C (room temperature) or at 4-6 degrees C (refrigerator) for 10 days as well as at -70 degr ees C for several months after blood sampling. A new chromatographic-i nterfering hemoglobin fraction both from venous and capillary samples was identified as free alpha-chain of hemoglobin. CONCLUSIONS - The Hb A(1c) filter paper system enables capillary blood sampling at home, el iminates the need of vein puncture in children and adults, and provide s the diabetologist with an HbA(1c) value when the patient visits the clinic without a need for a previsit phlebotomy.