Hematocrit: maturity relationship in adolescence.

The time of onset of adolescence, the velocity of change, and the age at which somatic maturity occurs varies with each individual. Chronologic age, per se, provides little information as to growth and development. The sequential changes in secondary sex characteristics can be divided into five stages and then one of these assigned as a "maturity rating" to any patient. Hematocrit determinations were performed on 1,007 girls and 1,000 boys, aged 11 to 20 years. All patients were from low-income families and each boy or girl was examined and classified according to maturity rating, sex, and color. In boys, correlation of hematocrit determinations and sex maturity ratings showed an increase in the hematocrit percentage with an increase of maturity rating. Boys have a smooth, progressive rise in hematocrit levels as they mature and this increase is apparently associated with the production of testosterone and the development of greater muscle mass. Hematocrit values increase in relation to chronologic age, only when sexual maturation is taking place, thus evaluation of anemia based only on age may be incorrect. Hematocrit determinations related to sex maturity ratings provide a logical criterion for the diagnosis of anemia and of therapeutic response in its treatment.