Sex, sport, and body-size dependency of hematology in highly trained athletes.

Blood hemoglobin concentration, hematocrit, red cell count, white cell count (WBC), and plasma ferritin concentration were measured on 1604 occasions from 706 nationally ranked athletes in 12 sports. The blood samples were taken from a forearm vein amidst periods of moderate to intense training but at least 6 h after a training session. A multiple regression model, accounting for correlations between variables and incorporating the categorical variables of sex and sport revealed the following. Each blood variable was found to be dependent on body mass index, (mass/height2, BMI), with the exception of WBC in the males. As BMI increased so did the magnitude of these blood variables (P less than 0.01). Each blood variable was also dependent on the sport (P less than 0.01), significant differences being observed between several sports in each case. Furthermore, as has been previously reported, the magnitude of the blood variables was dependent on the sex of the athlete, each being significantly greater in males (P less than 0.01), with the exception of the WBC, which was greater in females (P less than 0.01). These data indicate that the rationality of interpreting the hematology in highly trained athletes may be increased by taking BMI and sport into account, as well as gender.