Study of growth hormone secretion and action in growth-retarded children with juvenile chronic arthritis (JCA)

The stimulated and spontaneous growth hormone (GH) secretion and the respon se to GH action were assessed in growth-retarded children with juvenile chr onic arthritis (JCA), in order to determine the underlying mechanisms of gr owth retardation in such children. Six children (4 boys and 2 girls aged 10 .7-13.8 years) with active JCA of systemic onset were included in the study which involved: (1) anthropometric measurements; (2) assessment of GH resp onses to insulin-induced hypoglycaemia and clonidine stimulation; (3) asses sment of the nocturnal pulsatile GH secretion by measuring GH in blood samp les obtained every 20 min from 20.00 to 08.00 h; and (4) the IGF-I generati on test. As a control, the latter test was also performed in eight aged-mat ched children with physiological delay in puberty. Biosynthetic hGH (0.1 IU /kg BW) was administered s.c. for 4 days and blood samples were taken at ba seline and the morning after the last GH injection for measurement of IGF-I and IGFBP-3. All six children with JCA were prepubertal and their growth velocity was <3 cm/year. The GH responses to both stimulation tests were normal (peak GH > 20 mU/l). Analysis of the pulsatile GH secretion during the night revealed three-to-four GH pulses of normal amplitude (>20 mU/l). IGF-I (26.7+/-4.6 n mol/l, mean+/-SD) and IGFBP-3 (2.1+/-0.2 mg/l) levels were lower in the pat ients compared with the controls (43.0+/-3.7 nmol/l and 2.8+/-0.2 mg/l, res pectively, P <0.01). Following stimulation with exogenous hGH, there was a significant increase in IGF-I and IGFBP-3 levels in the control group (85 a nd 73%, respectively), but only a small increase in the patients (31 and 14 %). It appears that stimulated and spontaneous GH secretion is normal in childr en with active systemic JCA, but the response to endogenous and exogenous G H with regard to IGF-I and IGFBP-3 production is impaired, indicating a deg ree of GH insensitivity in such children. (C) 1999 Churchill Livingstone.