Endocrine Practice Question

A patient undergoes head trauma resulting in damage to the pituitary stalk, with severing of the connection between the hypothalamus and pituitary. Which pituitary hormone would most likely be increased as a result?

Show Answer and Explanations

Growth hormone

Incorrect. Growth hormone is decreased when connection between the hypothalamus and pituitary is severed.

Prolactin — Correct answer

Correct. Prolactin is unique among it's pituitary hormone counterparts in that it does not have a dedicated releasing hormone. However, the hypothalamus is still able to provide a feedback loop on prolactin because it produces dopamine, with is a potent inhibitor of prolactin. When the connection between the hypothalamus and pituitary is severed, all of the pituitary hormones will decrease (due to lack of stimulation from their releasing hormones), except for prolactin. Prolactin, in fact, will be increased because it is no longer inhibited by dopamine. This is known as the "stalk effect".

Follicle stimulating hormone

Incorrect. Follicle stimulating hormone is decreased when connection between the hypothalamus and pituitary is severed.

Adrenocorticotrophic hormone

Adrenocorticotrophic hormone is decreased when connection between the hypothalamus and pituitary is severed.

Thyroid stimulating hormone

Thyroid stimulating hormone is decreased when connection between the hypothalamus and pituitary is severed.

Summary