Partial growth hormone deficiency in adults; should we be looking for it?

Quantitatively, GH secretion exists as a continuum in states ranging from good health through to hypopituitarism. Currently, GH replacement is considered only for adults designated as being severely GH deficient (GHD). In clinical practice the gold standard, on which the biochemical diagnosis of severe GHD is based, centres on the presence of two or more additional anterior pituitary hormone deficits. Cohorts of adults with partial GHD (Growth Hormone Insufficiency [GHI]) have been reported with adverse body composition changes, dyslipidaemia, insulin resistance, altered cardiac performance and increased carotid intima-media thickness. The diagnosis of GHI in an individual patient, however, is extremely difficult because such patients rarely exhibit additional anterior pituitary hormone deficits, and the levels of GH-dependent proteins, including IGF-I, are normal in the majority. Currently, GH replacement therapy should only be considered in a patient characterized as GHI by dynamic GH testing in whom there is a plausible cause for hypopituitarism and in whom the IGF-I level is pathologically low.