Reliability of capillary hemoglobin screening under routine conditions

Capillary hemoglobin (Hb) measurement before admission for whole blood donation is performed in many blood donation services, in spite of several studies reporting many donors with low Hb values being missed by capillary Hb screening.

Predonation capillary and venous Hb levels of 9209 first-time donors presenting for whole blood donation were compared. Hb testing was conducted by photometric determination of finger-stick samples with a photometric method (Donor Checker, HemoCue) and using a hematology analyzer for venous samples.

Both capillary and venous Hb measurements were available for 8910 donors (96.8%). The arithmetic mean deviation of the capillary Hb from the venous sample was +1.5 ± 6.8 g/L, and the mean deviation was 5.4 ± 4.5 g/L. In 7865 donors (88%), capillary and venous Hb values differed less than 10 g/L from each other, but in 86 donors (1.0%) the difference was at least 20 g/L, and in 10 donors (0.1%), even 30 g/L or more. In 93.3% of females and 98.7% of males, the categorization as having sufficient or too low Hb for blood donation was concordant between capillary and venous measurements. A total of 34.4% of donors with too low results of capillary Hb screening had sufficient venous Hb levels. Only one donor (0.01%) passed the capillary Hb screening despite venous Hb values below 110 g/L.

The currently available methods for capillary Hb screening allow reliable determination of predonation Hb values under routine conditions. Additional venous Hb measurements in donors with too low capillary Hb values might reduce the rate of deferred donors by approximately one-third.