A person sustains head trauma leading to transection of pituitary stalk. All can be consequence of this, except –
## Core Concept
The pituitary stalk, also known as the infundibulum, connects the hypothalamus to the pituitary gland and plays a crucial role in the transport of hypothalamic-releasing and inhibiting hormones to the anterior pituitary gland. Transection of the pituitary stalk disrupts this communication, leading to various endocrine disturbances.
## Why the Correct Answer is Right
Transection of the pituitary stalk interrupts the delivery of hypothalamic-releasing hormones (e.g., TRH, GnRH, CRH) and inhibiting hormones (e.g., somatostatin, dopamine) to the anterior pituitary gland. This typically results in decreased secretion of anterior pituitary hormones, except for prolactin, which increases due to the loss of inhibitory control by dopamine from the hypothalamus.
## Why Each Wrong Option is Incorrect
- **Option A:** Decreased ACTH (adrenocorticotropic hormone) secretion can occur due to reduced CRH (corticotropin-releasing hormone) delivery, leading to decreased cortisol production. Thus, it's a possible consequence.
- **Option B:** Hyperprolactinemia can occur because the stalk transection reduces dopamine's inhibitory effect on prolactin release from the lactotroph cells of the anterior pituitary. So, this is a consequence.
- **Option C:** Reduced gonadotropin (LH and FSH) secretion can happen due to decreased GnRH delivery, affecting reproductive functions. This is also a consequence.
- **Option D:** Increased GH (growth hormone) secretion is not typically a direct consequence of pituitary stalk transection. Instead, GH secretion is often decreased due to reduced GHRH (growth hormone-releasing hormone) and increased somatostatin delivery to the pituitary.
## Clinical Pearl / High-Yield Fact
A key clinical pearl is that pituitary stalk transection often leads to **hyperprolactinemia** and **deficiencies of other anterior pituitary hormones**. This condition can result from head trauma, as in the question, or from other causes like pituitary tumors.
## Correct Answer Line
**Correct Answer: D. Increased GH secretion.**