Chronic growth retardation with normal GH secretion and low somatomedin activity

Four prepuberal children, two girls and two boys, aged 7 years 3 months to 11 years 6 months with chronic growth retardation were studied. Informed parental consent was obtained. Growth was followed for two years or more and was always less than P3. Growth velocity during observation period was 4 cm/y or less. Gastrointestinal, hepatic, renal and thyroid functions were normal. Skeletal X-ray examination revealed no anomalies. Cariotype in the two girls was 44XX. Growth hormone (GH) secretion was evaluated in all cases by two different test: exercise-propanolol and insulin-induced hypoglycemia. Peaks of GH secretion were 10 ng/ml or more. In three patients, GH secretion was also evaluated during first two hours of deep-sleep. GH peaks were 10, 4 and 13.4 ng/ml, respectively. Somatomedin activity (SA) measured in basal condition on two different days with six month interval was low (0.28-0.70 U/ml) and increased after seven daily doses of 2 mg of GH, in all patients (0.80-1.12 U/ml). All patients were treated with GH (2 mg/3 times/week), and growth velocity increased from 4 to 8.7, from 3.9 to 8.8, from 3 to 6.5 and from 3.2 to 6 cm/y, respectively. In conclusion, SA is of value in selection of patients with chronic growth retardation, who may benefit from long-term GH therapy.