Britannica Sources used in this answer

Why can radiation exposure to the pituitary or thyroid gland cause hormone deficiencies?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

linear accelerator; external beam radiation therapy — radiation therapy External beam radiation therapy (also known as external beam teletherapy, or long-distance therapy) being delivered using a machine known as a linear accelerator.

Radiation therapy is a targeted treatment, but when the pituitary gland or thyroid gland is directly exposed to high doses of radiation, it can cause long-term, permanent damage to these tissues.1

Hormone deficiencies occur because radiation can lead to the destruction or hypofunction of these endocrine glands. While complete destruction is rare, significant damage to the gland's cellular structure—whether through physical trauma, inflammation, or radiation exposure—impairs its ability to synthesize and secrete hormones effectively.21

Because these glands serve as primary sources for specific hormones, their inability to function at full capacity results in endocrine hypofunction. These long-term side effects are generally permanent and depend on factors such as the radiation dose and the patient's age at the time of treatment.21