'Neutropenia' in black west Indians.

A prospective case control study routine haematological parameters was conducted in 294 healthy Black and White age/sex-matched subjects. The most important finding relevant to clinical practice was a reduction of total white cell count in Blacks due mainly to reduced neutrophil numbers. Twenty-one percent of sickle negative Blacks had white cell counts below the lowest value seen in Whites. The haemoglobin concentration, erythrocyte mean cell volume and monocyte count were also significantly lower amongst Blacks though lymphocyte counts were higher. The racial differences in haemoglobin and white count were not accounted for by differences in smoking and drinking habits. They were also found when Blacks with sickle cell trait were compared to age/sex-matched Whites and in others taking the oral contraceptive pill. Awareness of racial group should aid interpretation of routine tests and avoid unnecessary investigation of normal 'neutropenic' Blacks.