THE CAPACITY TO INCREASE GH SECRETION AT PUBERTY REFLECTS THE SEVERITY OF GH DEFICIENCY

This study evaluates the effect of the spontaneous pubertal increase i n sex steroids on GH secretion in GH-deficient patients. Fifteen patie nts (10 boys, 5 girls) with idiopathic isolated GH deficiency diagnose d before puberty (GH peak < 8 mug/l after 2 arginine insulin stimulati on tests) were reevaluated for their GH secretion using the same test after completion of their hGH therapy and puberty. Their ages at diagn osis and at the last evaluation were 8.2 +/- 0.7 (SE) (range 4.9-14.9) and 17.8 +/- 0.3 years (15-23), respectively. The data at diagnosis a nd at last evaluation showed that (1) the mean height increased from - 4 +/- 0.3 to -2.5 +/- 0.3 SD (p < 0.01), (2) the mean GH peak increase d from 4.4 +/- 0.3 (1.6-8) to 7.6 +/- 0.8 mug/l (2-13.2, p < 0.0l); at the last evaluation, 8/15 patients had GH peak > 8 mug/l and (3) the mean plasma insulin-like growth factor I increased from 0.28 +/- 0.05 to 0.42 +/- 0.03 U/ml (n = 6, p < 0.05). The mean increase in the GH p eak was 3.2 mug/l (-3 to 10.6). It was negatively correlated with the degree of growth retardation at diagnosis (r = -0.74, p < 0.005). We c onclude that the increase in the GH peak at puberty in patients with G H deficiency reflects the severity of GH deficiency and that a correct ive factor of the cutoff number is necessary for the diagnosis of GH d eficiency in puberty.