Role, sensitivity and validity of GH stimulation tests in the diagnosis of growth hormone deficiency in adults.

This study was conducted to evaluate whether stimulated concentrations of growth hormone (GH) are of practical use in establishing the diagnosis of acquired GH deficiency. The secretion of GH as stimulated by GH releasing hormone (GHRH; 100 microg i.v.) was studied in 33 patients with non-functioning pituitary macroadenomas prior to and after trans-sphenoidal adenomectomy, as well as in 25 non-selected subjects who had been referred for evaluation of various suspected non-pituitary diseases. Patients with pituitary macroadenomas, who needed substitution therapy for at least one additional pituitary hormone, presented with lower (P<0.05) GHRH-stimulated GH secretion (3.2 +/- 4.3 ng/ml) than the remaining patients with pituitary tumours (7.2 +/- 6.6 mg/ml). Both groups showed a marked overlap with the control group (7.1 +/- 5.5 ng/ml). Although GH stimulation tests are superior to other biochemical criteria of GH deficiency, they are still an inadequate method to reliably diagnose GH deficiency in an individual patient. In clinical practice GH replacement therapy should, therefore, only be considered if, in addition to impaired GH secretion, the patients present with additional defects in anterior pituitary function and clinical symptoms are compatible with a lack of GH.