Long-term effects of growth hormone (GH) replacement therapy on hematopoiesis in a large cohort of children with GH deficiency.
OBJECTIVE Recombinant human growth hormone is being used increasingly in the treatment of GH deficiency in adults. In addition to erythropoietin, insulin-like growth factor-I (IGF-I) has been demonstrated to stimulate hematopoiesis in animals, especially rodents. We have determined the effect of growth hormone (GH) administration on haematopoiesis. PATIENTS AND DESIGN Seventeen patients (10 males and 7 females; mean age 47 +/- 2 years; range 30-59) with biochemically proven adult-onset GH deficiency (GHD) were treated with human recombinant growth hormone (rhGH) as replacement therapy for more than 96 weeks in a dosage of 12.5 micrograms/kg/day (initial dosage during the first 4 weeks 6.25 micrograms/kg/day). The diagnosis of GHD had been confirmed using a standard arginine-infusion test (0.5 g/kg body weight). Blood samples were collected for safety and efficacy parameters before and during the GH treatment period. MEASUREMENTS Routine methods were used for the haematological and biochemical measurements. IGF-I concentrations were measured, using a commercial RIA kit. RESULTS From week 36 and onwards, we observed a significant increase in individual haemoglobin (Hb) concentrations, especially in the male patients. Mean Hb in the male patients before treatment amounted to 9.1 +/- 0.2 mmol/l (range 8.1-10.5) and increased by 0.93 +/- 0.2 mmol/l (P < 0.05) after 120 weeks of rhGH replacement therapy. The mean Hb concentration in female patients before treatment was 8.1 +/- 0.1 mmol/l and an increase of 0.32 +/- 0.1 mmol/l (P < 0.05) was observed after 120 weeks. For all 17 patients the mean increase in Hb after 120 weeks was 0.73 +/- 0.2 mmol/l (P < 0.05). IGF-I concentrations also increased during therapy from 86 +/- 9 pg/l to 253 +/- 26 pg/l within 24 weeks (P < 0.05). No significant changes in leucocyte or platelet counts were found. CONCLUSIONS Long-term replacement therapy with rhGH in patients with adult-onset GHD induces a significant increase in Hb concentrations, while serum leucocyte and platelet counts do not change.