A 32 year old female underwent whole-brain irradiation therapy following tumor growth in the brain. Most common hormone deficiency seen after intracranial radiation therapy is:
**Core Concept**
Intracranial radiation therapy can lead to damage of the hypothalamic-pituitary axis, resulting in hormonal deficiencies due to the loss of pituitary function. The hypothalamus and pituitary gland are crucial for regulating various endocrine functions.
**Why the Correct Answer is Right**
The most common hormone deficiency seen after intracranial radiation therapy is growth hormone (GH) deficiency. This is because the somatotrophs, the cells responsible for producing growth hormone, are located in the lateral wings of the pituitary gland, which are particularly susceptible to radiation damage. Growth hormone plays a vital role in regulating growth, metabolism, and body composition.
**Why Each Wrong Option is Incorrect**
**Option A:** Adrenocorticotropic hormone (ACTH) deficiency is also a possibility, but it is less common than GH deficiency. ACTH is produced by the corticotrophs, which are located in the anterior pituitary gland, but are less sensitive to radiation.
**Option B:** Thyroid-stimulating hormone (TSH) deficiency can occur, but it is rare. TSH is produced by the thyrotrophs, which are located in the anterior pituitary gland and are less sensitive to radiation.
**Option C:** Prolactin deficiency is not typically seen after intracranial radiation therapy, as prolactin is produced by the lactotrophs, which are more resistant to radiation damage.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the hypothalamic-pituitary axis is sensitive to radiation, and damage can lead to hormonal deficiencies. GH deficiency is the most common endocrine abnormality seen after intracranial radiation therapy.
**Correct Answer:** C. Growth hormone deficiency.