White blood cell counts in healthy Jamaican adults

The investigation of presumed neutropenia places a burden on the health services, especially those of developing countries, including Jamaica. This may be because the normal ranges used in the laboratory are based on the values generated from the Caucasian population. Previous studies looking at African and Afro-Caribbean groups have found lower counts for these populations compared with Caucasians. To address this issue, 195 healthy adults donating blood at the National Public Health Laboratory and the University Hospital of the West Indies blood banks in Kingston, Jamaica, were screened for complete blood count (CBC) differentials between June 2001 and June 2006. The geometric means for the neutrophil counts were found to be 2.4 x 10(9)/L for men and 2.7 x 10(9)/L for women, with 95% confidence intervals of 2.2-2.8 x 10(9)/L and 2.5-3.1 x 10(9)/L respectively. Values for the Jamaican population were similar to those of other Afro-Caribbean groups. Based on this distribution, 14% of healthy Jamaicans would fall below the normal ranges derived from Caucasians and therefore presumed to have neutropenia. We recommend that the lower reference ranges obtained for Afro-Caribbean adults be adopted for that population.