Hypopituitarism following radiotherapy

Area of Science:

• Endocrinology
• Radiation Oncology
• Neuroscience

Background:

• Radiation damage to the hypothalamic-pituitary (h-p) axis can lead to anterior pituitary hormone deficiencies.
• The severity and frequency of these deficiencies correlate with radiation dose and follow-up duration.
• The growth hormone (GH) axis is the most radiosensitive, making GH deficiency common.

Purpose of the Study:

• To investigate the incidence and characteristics of anterior pituitary hormone deficiencies following radiation to the h-p axis.
• To understand the dose-dependency and specific hormone axes affected.
• To highlight the long-term consequences and management strategies.

Main Methods:

• Analysis of hormone secretion following various radiation doses to the h-p axis.
• Assessment of GH, TSH, ACTH, and gonadotrophin deficiencies.
• Evaluation of spontaneous and stimulated hormone secretion, including insulin-induced hypoglycemia tests (ITT) in children.
• Long-term follow-up of patients treated for pituitary tumors and nasopharyngeal carcinomas.

Main Results:

• GH deficiency is frequent, especially at doses <30 Gy, and increases with higher doses (30-50 Gy).
• TSH and ACTH deficiencies occur at higher doses (>50 Gy).
• Gonadotrophin abnormalities (precocious puberty, deficiency) are dose-dependent.
• Hyperprolactinemia can occur due to hypothalamic damage.
• Deficiencies are irreversible and progressive, with higher incidences after intensive irradiation (>60 Gy).

Conclusions:

• Radiation-induced anterior pituitary hormone deficiencies are common, progressive, and irreversible.
• GH deficiency is the most frequent, followed by TSH, ACTH, and gonadotrophin deficiencies.
• Regular endocrine assessment and timely hormone replacement are essential for patient management.