Tall stature: a clinical, endocrinological and radiological study.

We have studied GH secretory dynamics in 38 (25 F, 13 M) children referred for investigation and treatment of tall stature (Height SD score (SDS) greater than 1.8). Five children had elevated basal GH levels (mean 20.4 mU/l) and a further four had abnormal GH responses to exogenous TRH. Two other children had paradoxical GH responses to oral glucose loading. Although one of these was receiving high dose testosterone to limit final height. All these children were pubertal and did not show concordance between peak GH concentration observed after insulin-induced hypoglycaemia and during stage IV sleep. Twenty-four hour GH profiles revealed increased GH pulse amplitude and area under the pulse during puberty. Morning GH secretion was also regularly observed and it is possible that the paradoxical responses seen by us and reported by others reflect this increased physiological secretion. Pituitary radiology revealed morphological abnormalities suggestive of microadenomata in 17 patients but these were all in late puberty and these changes may be related more to the effects of sex hormones than to somatotroph pathology. 'Abnormal' endocrinology and radiology are seen in tall children in puberty and must be interpreted with caution.