Platelet count and platelet size in healthy Africans and West Indians.

Healthy subjects of African origin were found to have lower platelet counts than simultaneously studied healthy Caucasians. A similar reduction was found in a large group of West Indian females, though not in a small group of West Indian males. It is suggested that the lower platelet counts observed in Africans and West Indians may be partly environmental and partly genetic in origin. The mean platelet volume and platelet distribution width in the Africans and West Indians showed the same relationship with the platelet count as was found in Caucasians, so that the same nomograms can be used in all ethnic groups to assess whether there is deviation from normality.