Racial difference in hemoglobin concentration of young adults.

Hemoglobin concentration was measured in 1,001 young adults (34% black, 66% white), ages 17 to 24 years, in a community survey. Hemoglobin levels were 0.9 g/dl lower in blacks than in whites (P less than 0.001) and 2.0 g/dl lower in females than in males (P less than 0.001). Black females had the highest prevalence of anemia (16%) and the lowest prevalence of polycythemia 3%), while white females had the lowest prevalence of anemia (1%) and highest prevalence of polycythemia (9%). Mean hemoglobin levels in females did not increase after approximately age 12 1/2 years, while those in males continued to increase until age 17 years. Regular cigarette smoking was a potent risk factor for polycythemia in white males. Number of cigarettes smoked per week and number of years as a regular smoker increased hemoglobin concentration. New criteria, based on population distribution of hemoglobin levels, may be needed for defining anemia and polycythemia in black populations and cigarette smokers.