Making a rational diagnosis of growth-hormone deficiency.

Growth hormone (GH) has been available for therapeutic use for more than 30 years, but there is still considerable debate about the best way to diagnose GH deficiency. This can be attributed to the existence of a variable degree of GH insufficiency in most cases and the fact that assays vary considerably between laboratories in terms of sensitivity and epitope specificity. These difficulties are compounded by the episodic nature of GH secretion and our reliance on a variety of provocative tests. A workshop and consensus report held in Portland, Oregon, in 1995 highlighted these issues and suggested a rational diagnostic approach that emphasizes good auxologic evidence, followed by assays of insulin-like growth factor I and insulin-like growth factor binding protein 3 to identify abnormalities in the GH axis. Actual assays of GH, during some provocative tests, are relegated to confirming that an identified abnormality in the GH-insulin-like growth factor axis is related to GH insufficiency rather than to GH resistance.