The difference between fingerstick and venous hemoglobin and hematocrit varies by sex and iron stores.
BACKGROUND
Fingerstick blood samples are used to estimate donor venous hemoglobin (Hb).


METHODS
Fingerstick Hb or hematocrit (Hct) was determined routinely for 2425 selected donors at six blood centers, along with venous Hb. Using sex and measures of iron status including absent iron stores (AIS; ferritin < 12 ng/mL), linear regression models were developed to predict venous Hb from fingerstick.


RESULTS
Across all subjects, fingerstick Hb was higher than venous Hb in the higher part of the clinical range, but lower in the lower part of the range. The relationship varied by sex and iron status. Across centers, a female donor had on average a venous Hb result 0.5 to 0.8 g/dL lower than a male donor with the same fingerstick Hb and iron status. Similarly, a donor with AIS had on average a venous Hb result 0.3 to 1.1 g/dL lower than an iron-replete donor with the same fingerstick value and sex. An iron-replete male donor with a fingerstick result at the cutoff (Hb 12.5 g/dL) had an acceptable expected venous Hb (12.8 to 13.8 g/dL). A female donor with AIS with a fingerstick result at the cutoff had an expected venous Hb below 12.5 g/dL (11.7 to 12.4 g/dL). Of females with AIS, 40.2% donated blood when their venous Hb was less than 12.5 g/dL.


CONCLUSIONS
Fingerstick is considered a useful estimator of venous Hb. However, in some donor groups, particularly female donors with AIS, fingerstick overestimates venous Hb at the donation cutoff. This significant limitation should be considered in setting donor fingerstick Hb or Hct requirements.
New England Region, American Red Cross Blood Services, 209 Farmington Avenue, Farmington, CT 06032, USA. CableR@usa.redcross.org
Ritchard G
RG
Cable
Whitney R
WR
Steele
Russell S
RS
Melmed
Bryce
B
Johnson
Alan E
AE
Mast
Patricia M
PM
Carey
Joseph E
JE
Kiss
Steven H
SH
Kleinman
David J
DJ
Wright
D001782:Blood Donors; D001800:Blood Specimen Collection / Q000379:methods*; D005260:Female; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007501:Iron / Q000378:metabolism*; D016014:Linear Models; D008297:Male; D012737:Sex Factors
D006454:Hemoglobins; D007501:Iron