Endocrine function following single fraction and fractionated total body irradiation for bone marrow transplantation in childhood.

Forty-nine children who had undergone treatment with cyclophosphamide and total body irradiation before bone marrow transplantation were investigated for impaired endocrine function. Twenty-six patients received single fraction total body irradiation as a dose of 9-10 Gy, whereas 23 patients received fractionated total body irradiation as a total dose of either 12 Gy divided into six fractions or 14.4 Gy divided into eight fractions, administered over 3 or 4 days. Half of the patients in the single fraction group and nine in the fractionated group had received cranial irradiation prior to total body irradiation. Pathological changes in thyroid function were observed in 19 patients (73%) of the single fraction group (elevated thyrotrophin (58%) and decreased thyroxine levels (15%)), whereas in the fractionated group only six patients (25%) developed transient raised thyrotrophin levels: the mean observation period was 3.2 years in the single fraction group and 2.7 years in the fractionated group. The stimulated growth hormone peak concentration was influenced significantly by previous cranial irradiation and was independent of the type of total body irradiation administered. In the patients who had received cranial irradiation, the mean growth hormone peak levels were 8.4 mU/l (single fraction group) and 13.9 mU/l (fractionated group), whereas in those who received only total body irradiation they were 24.9 mU/l(single fraction group) and 28.1 mU/l (fractionated group). The basal gonadotrophin concentration in children older than 9 years showed elevated levels in nine patients (50%) of the single fraction group and in only three patients (30%) of the fractionated group.(ABSTRACT TRUNCATED AT 250 WORDS)