Endocrine Abstracts

There is little information on the effects on pituitary function of cranial irradiation for non-pituitary tumours. We have studied anterior and posterior pituitary function in 17 patients (6 males), with a median age 19 years (range 5-48) at the time of radiotherapy. 16 patients had primary brain tumours and one had acute lymphocytic leukaemia. The patients were selected by the radiotherapists for investigation . Pituitary functions were assessed at a median of 60 months (range 6-312) after the administration of a median dose of 54 Gray (range 18-55). Adreno-cortictrophin hormone (ACTH) and growth hormone (GH) deficiencies were identified by either the insulin tolerance test (9/17) or the glucagon stimulation test (8/17), thyrotrophin (TSH) by thyrotrophin releasing hormone testing and gonadotrophin deficiencies by gonadotrophin releasing hormone testing and basal sex hormone concentrations. Diabetes insipidus was defined by water deprivation test. 13/17 had GH deficiency (peak GH response less than 10 nanograms per millilitre), including 11 patients with severe GH deficiency (peak GH less than 3 nanograms per millilitre). 11/17 patients had ACTH deficiency (peak cortisol < 500 nanomole per litre), 6/17 had TSH deficiency and 7/17 had gonadotrophin deficiency. 2 patients had evidence of diabetes insipidus and 9 patients had hyperprolactinaemia. 15/17 patients had at least one hormone deficiency.
In this selected series, there was a high prevalence of pituitary hormone deficiencies in patients who had undergone cranial irradiation for non-pituitary disease. A larger, unselected, prospective study is necessary to determine the true prevalence and timing of pituitary hormone abnormalities in such patients. Clinicians should be aware of the possibility of the likelihood of treatable hormone deficiencies in this patient group.