Radiotherapy-induced hypopituitarism: a review

Abstract

Hypopituitarism is a disorder caused by impaired hormonal secretions from the hypothalamic-pituitary axis. Radiotherapy is the most common cause of iatrogenic hypopituitarism. The hypothalamic-pituitary axis inadvertently gets irradiated in patients receiving prophylactic cranial radiotherapy for leukemia, total body irradiation and radiotherapy for intracranial, base skull, sinonasal and nasopharyngeal tumors. Radiation-induced hypopituitarism (RIH) is insidious, progressive and largely nonreversible. Mostly, RIH involves one hypothalamic-pituitary axis; however, multiple hormonal axes deficiency starts developing at higher doses. Although the clinical effects of the hypopituitarism are more profound in children and young adults, its implications in older adults are being increasingly recognized. The risk continues to persist or increase up to 10 years following radiation exposure. The clinical management of hypopituitarism is challenging both for the patients and healthcare providers. Here we have reviewed the scale of the problem, the risk factors and the management of RIH.

Hormonal dysfunction is frequent in cancer survivors treated with radiotherapy to the head and neck region

“…There was a significant relationship between pituitary dysfunction and radiation dose of 30 Gy or higher to the pituitary gland, confirming previous reports that the prevalence of pituitary dysfunction is related to radiation dose to the pituitary gland [14]. Pituitary dysfunction has also been reported to be related to observation time, but this we could not confirm [17].…”

“…The threshold of 30 Gy was chosen since deficiencies in the HP axis in adults have been reported to appear mainly at doses above 30 Gy [17].…”

“…The HP-thyroid and HP-adrenal axes are even more radioresistant, but hormonal dysfunction in these axes has been described as frequent after higher doses (≥50 Gy) to the pituitary gland [14,16]. So far, no general threshold of radiation dose at which pituitary dysfunction develops has been demonstrated, although hormonal dysfunction has been reported to be rare in adults after radiation doses less than 30 Gy to the pituitary gland [17].…”

Outcome of radiotherapy for pituitary adenomas

“…[14][15][16][17] The risk of pituitary complication remains stable after 8-10 years. 7,18 Our study showed 6.4% hypopituitarism and 5 out of 6 patients (83%) had new onset hypopituitarism post RT. Our results are lesser when compared to published results and one of the reasons could be that a median follow-up period was only 6 years in our study.…”

Conséquences endocriniennes, osseuses et métaboliques des greffes de cellules souches hématopoïétiques allogéniques chez l’adulte

“…Par ailleurs, il est connu que l'irradiation encéphalique à dose <24 Gy n'induit pas d'insuffisance thyréotrope. 55 Nous avons peut-être diagnostiqué par excès deux insuffisances thyréotropes alors qu'il pourrait s'agir d'une diminution de la T4 libre secondaire à une pathologie aigüe ou chronique, comme il existe une diminution de la T3 (triiodothyronine) libre dans ces mêmes conditions (syndrome de basse T3). Néanmoins, les patients évalués en Endocrinologie sont en rémission complète et dans une situation médicale reconnue comme stable vis à vis de leur pathologie hématologique.…”