Hypothyroidism a Sequela of Cranial Irradiation of Pediatric Brain Tumor

Researchers from University Hospital, Copenhagen, Denmark have found that both craniospinal and cranial irradiation from a childhood brain tumor may affect thyroid function.

The study compared the effects of craniospinal irradiation and cranial irradiation (with or without chemotherapy) on the hypothalamus/pituitary (HP)- thyroid axis in patients treated for a childhood brain tumor. Thyroid function was compared to controls and patients were followed for a median of 12 years.

24% of patients had primary hypothyroidism. Of these, 70% had been treated with craniospinal irradiation and 30% with cranial irradiation. Treated patients had significantly lower free T4 and total T3 compared to the controls. Researchers believe this is due to scattered irradiation from both cranial and spinal fields to the thyroid gland.

Researchers recommend prolonged surveillance of pituitary-thyroid function in long-term survivors of childhood brain tumor and institution of thyroid replacement if the levels of TSH and free T4 are above and below the normal range, respectively, to ensure normal growth and metabolism.

(Source: Journal of Clinical Endocrinology and Metabolism 2003; 88:136-140)