Endocrine and reproductive dysfunction following fractionated total body irradiation in adults.

The endocrine and reproductive sequelae of total body irradiation for haematological malignancy have been studied in 21 patients (11 male) who were treated with 10 Gy in five fractions or 12 or 13.2 Gy in six fractions over 3 days. Eighteen patients (eight male) aged 16-49 years underwent dynamic tests of the hypothalamic-pituitary axis with insulin hypoglycaemia, thyrotrophin releasing hormone (TRH) and gonadotrophin releasing hormone stimulation and basal measurement of prolactin, sex steroids and thyroid hormones. Growth hormone responses (mean peak 64 +/- 36 mU/l, range 21-146 mU/l) and cortisol responses (mean peak 831 +/- 122 nmol/l, range 626-1105 nmol/l) were all within the normal range. Two patients had minimally elevated serum prolactin levels (445 and 588 mU/l, normal less than 350 mU/l). Serum thyroxine levels (57-133 nmol/l) were normal but six patients had elevated basal thyrotrophin (TSH) levels (6-9 mU/l) and seven had an exaggerated TSH response to thyrotrophin releasing hormone, indicating radiation-induced damage to the thyroid. Amenorrhea developed within 3 months of irradiation in all females and oestradiol levels were low, at 37-108 pmol/l (mean 58 +/- 22 pmol/l). Severe oligospermia or azoospermia was noted in men tested 5-70 months after irradiation and testicular volume was below the normal adult range in five of seven men assessed. Serum testosterone levels (12.4-35 nmol/l) were normal. Gonadotrophin-releasing hormone-stimulated gonadotrophin levels were elevated in all patients. However, two men have fathered two children each; one has refused semen analysis, but the other has a sperm count of 7 x 10(6)/ml (60 per cent motile, 20 per cent abnormal forms) 70 months after irradiation. When given by the above fractionated regimens, the endocrine sequelae of total body irradiation are limited to gonadal failure requiring oestrogen replacement in women and severe impairment of fertility in men. Subclinical thyroid dysfunction has been seen in 39 per cent of patients there is no evidence of direct damage to the hypothalamic pituitary axis.