L-Dopa Is a Potent Stimulator of Cortisol in Short Children

Aims: In this study, we evaluated the diagnostic usefulness of oral L-dopa as a stimulatory agent for cortisol. Methods: In 27 short children that were evaluated for possible growth hormone deficiency (GHD), the levels of serum GH and cortisol were determined after oral L-dopa administration and after i.m. glucagon administration. We defined cortisol concentrations > 18 mu g/dl (496 nmol/l) as adequate response. Peak GH concentration < 10 ng/ml in both tests defined GHD. Results: Twenty-five out of the 27 children (93%) studied showed a normal cortisol response, i.e. a peak serum cortisol > 18 mu g/dl in the L-dopa test, whereas 19 children (70%) had a normal cortisol response after stimulation with glucagon. In the children with normal cortisol response in both tests, the mean peak serum cortisol concentration was 28.7 (SD 1.59) after L-dopa and 26.65 (SD 1.26) mu g/dl after glucagon administration. There was no statistically significant difference in peak serum cortisol response to L-dopa between GH-deficient and GH-sufficient children [25.90 (SD 4.9) vs. 29.87 (SD 9.9) mu g/dl, respectively]. Conclusions: These results clearly suggest that L-dopa administration is a potent stimulus for cortisol secretion at least in short children. (C) 2014 S. Karger AG, Basel