Blood erythrocyte and hemoglobin concentrations in premature adrenarche.

CONTEXT: Premature adrenarche (PA) is characterized by an earlier than normal increase in adrenocortical androgen production, and it is associated with increased serum IGF-I concentrations. Both the GH-IGF system and androgens, particularly testosterone, are known to enhance erythropoiesis.

OBJECTIVE: Our objective was to test the hypothesis that blood erythrocyte count and blood hemoglobin (B-Hb) concentration are increased in PA.

DESIGN, PARTICIPANTS, AND SETTING: Sixty-four prepubertal children (10 boys) with clinically and biochemically defined PA and 62 healthy prepubertal controls (10 boys) participating in our Premature Adrenarche study were examined, and a fasting blood sample was drawn at a university hospital.

MAIN OUTCOME MEASURES: We evaluated B-Hb and erythrocyte, thrombocyte, and leukocyte counts and their association with serum dehydroepiandrosterone sulfate (DHEAS), testosterone and IGF-I concentrations.

RESULTS: Children with PA had higher mean blood erythrocyte count (4.74 vs. 4.64 × 10(12)/liter, P = 0.04; significant difference in girls but not in boys) and a tendency toward higher B-Hb (130 vs. 128 g/liter, P = 0.06) than their controls. No difference was observed in leukocyte or thrombocyte counts between the study groups. In linear regression models including age, sex, body mass index SD score, IGF-I, and DHEAS or testosterone, B-Hb was associated with serum DHEAS (P = 0.04), testosterone (P = 0.01), and IGF-I (P ≤ 0.003) concentrations in the entire study cohort and with IGF-I separately in girls (P ≤ 0.02). Similar models showed a significant association of blood erythrocyte count with serum IGF-I concentration (P = 0.003-0.049) but not with DHEAS or testosterone.

CONCLUSIONS: Increased erythrocyte count in PA girls suggests that relatively small increases in serum androgen or IGF-I concentrations during adrenarche may associate with enhanced erythropoiesis.