In contrast to the sustained acceleration of growth observed in pituitary hypersecretion of GH, full catch-up growth is rarely attained in GH deficiency with conventional GH Rx (0.1 U/kg IM 3x/wk). Since circulating GH levels are very low for all but 24-30 hr per wk during conventional Rx, we examined the feasibility and short term metabolic effects of CSIGH using a small infusion pump. Fasting levels of glucose (G), insulin (I), free fatty acids (FFA) and oral glucose tolerance were determined in 5 previously untreated deficient children before and after 85 hrs of CSIGH (dose 2.1 μU/kg/hr ∼ 0.3 U/kg/wk). CSIGH maintained serum GH levels at 3-9 ng/ml during the infusion. As shown in the table, CSIGH produced a modest increase in fasting (0 min) G and I. Furthermore, glucose tolerance was impaired despite 2-fold higher I levels (*p