Comparison of physiological and pharmacological tests of growth hormone function in children with short stature.

We studied 30 short-statured children to investigate their 24-h integrated serum concentration of GH (ICGH) and its diurnal pattern and to compare this data with their responses to standard stimulation tests for GH release. Eight patients with normal stimulation tests had a mean (+/- SD) ICGH value of 8.0 +/- 3.8 ng/ml (range, 4.5--16.4), and all had several secretory peaks greater than 12 ng/ml. Nineteen patients with abnormal responses (peak, less than 10 ng/ml) had a mean ICGH value of 2.7 +/- 1.9 ng/ml (range, less than 0.8 to 7.0); this was significantly lower than that of control subjects and patients with normal stimulation tests. However, 5 of these patients had normal ICGH values. Three patients with borderline stimulation test responses (10--12 ng/ml) had normal ICGH values (3.2, 3.4, and 11.9 ng/ml). Of the 22 patients with either abnormal or borderline stimulation tests, 14 had an ICGH result below the range of normal. Of these 14, 11 had no secretory peaks greater than 10 ng/ml, whereas 3 had peaks between 10--12 ng/ml. The 8 other patients had ICGH results in the normal range. Despite significant correlation (r = 0.668), integrated GH values did not correlate with stimulation tests in a minority of the patients, the status of whom remains to be determined by long term response to exogenous GH therapy.