Juvenile rheumatoid arthritis. Effects of disease activity and recombinant human growth hormone on insulin-like growth factor 1, insulin-like growth factor binding proteins 1 and 3, and osteocalcin.

OBJECTIVE

To investigate possible mechanisms of growth impairment in children with juvenile rheumatoid arthritis (JRA).

METHODS

Eighteen prepubertal children with JRA and growth retardation received recombinant human growth hormone (rHuGH) for 1 year. Growth hormone profiles over 24 hours were obtained before treatment in 12 patients; the levels did not differ from those in "short normal" children. Levels of insulin-like growth factor 1 (IGF-1), IGF binding proteins (IGFBPs) 1 and 3, insulin, osteocalcin, and C-reactive protein (CRP), as well as the erythrocyte sedimentation rate were measured serially. Pretreatment levels were compared with control levels.

RESULTS

In JRA patients, IGF-1, IGFBP-3, and osteocalcin levels were significantly lower and insulin levels significantly higher than those in controls, but there was no significant difference in the level of IGFBP-1. With rHuGH treatment, height velocity and mean levels of IGF-1, osteocalcin, and insulin increased significantly, while mean levels of IGFBP-1 fell significantly. Levels of IGFBP-3 correlated with those of IGF-1. The height velocity correlated positively with IGF-1 and osteocalcin, and negatively with IGFBP-1. Levels of IGFBP-1 were inversely related to those of insulin and IGF-1. There was a significant negative correlation between the CRP and height velocity, IGF-1 level, and osteocalcin level.

CONCLUSION

IGF-1 production is impaired in children with active JRA. Treatment with a therapeutic dose of rHuGH can rectify the IGF-1 deficiency within 4 days, but its effect is adversely influenced by the acute-phase response, as reflected by an elevated CRP level.