Hemoglobin measured by Hemocue and a reference method in venous and capillary blood: a validation study.
OBJECTIVE
To assess the comparability of hemoglobin concentration (Hb) in venous and capillary blood measured by Hemocue and an automated spectrophotometer (Celldyn) and to document the influence of type of blood (capillary or venous) and analysis method on anemia prevalence estimates.


METHODS
Between February and May 2000, capillary and venous samples were collected from 72 adults and children at Hospital del Niño Morelense (Morelos State Children's Hospital) in Cuernavaca, Morelos, Mexico, and assessed for Hb using the Hemocue and Celldyn methods. Estimated Hb levels were compared using the concordance correlation coefficient and Student's t test for paired data. The sensitivity and specificity for anemia diagnosis were estimated and compared between type of blood and method of assessment.


RESULTS
Capillary blood had higher Hb (+0.5 g/dl) than venous blood in adults and children, as did samples assessed by Celldyn compared to Hemocue (+0.3 g/dl). Specificity to detect anemia was adequate (> 0.90) but sensitivity was low for capillary blood assessed by Hemocue (< 0.80).


CONCLUSIONS
The difference in Hb between venous and capillary blood is likely related to biological variability. Hemoglobin concentration in capillary blood assessed by Hemocue provides an adequate estimation of population anemia prevalence but may result in excess false negative diagnoses among individuals. The results of this study stress the importance of sample collection technique, particularly for children. Method of analysis and sampling site need to be taken into consideration in field studies. The English version of this paper is available too at: http://www.insp.mx/salud/index.html.
División de Epidemiología de la Nutrición, Centro de Investigaciones en Nutrición y Salud, Instituto Nacional de Salud Pública, Av. Universidad 655, colonia Santa María Ahuacatitlán, 62508 Cuernavaca, Morelos, México. lneufeld@correo.insp.mx
Lynnette
L
Neufeld
Armando
A
García-Guerra
Domingo
D
Sánchez-Francia
Oscar
O
Newton-Sánchez
María Dolores
MD
Ramírez-Villalobos
Juan
J
Rivera-Dommarco
D000293:Adolescent; D000328:Adult; D000368:Aged; D000740:Anemia / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology; D001774:Blood Chemical Analysis / Q000295:instrumentation; D002196:Capillaries; D002648:Child; D002675:Child, Preschool; D005260:Female; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012016:Reference Values; D014680:Veins
D006454:Hemoglobins