Incidence of anterior pituitary deficiency after radiotherapy at an early age: study in retinoblastoma.

Thirty-one patients treated for retinoblastoma in the first few years (3 months to 3 years and 6 months) of life were studied 2 to 15 years later. Radiotherapy delivered 1 300 to 6 500 rads to the hypothalamo-pituitary area. Growth deficiency was documented in 30% of all cases. Other pituitary deficiencies were the exception. The critical dose for GH insufficiency is between 2 000 and 3 000 rads, as in older children or adults. Our study does not support the hypothesis that the hypothalamo-pituitary area is more sensitive to radiation at an early age. Furthermore, conservative therapy of retinoblastoma leads to double lateral irradiation and will increase the number of GH deficient children after retinoblastoma.