While doing your rounds, you see a 6 year-old named Alex who presents with severe headaches and vision impairment which began six months ago. More specifically, he has some difficulty seeing things on the periphery, what he describes as tunnel vision. Examination reveals bitemporal hemianopia and a much taller stature than expected for his age, with disproportionately long arms and legs. Soon after, you see Maria, who says she has been unsuccessfully trying to have a baby for the last two years. She also mentions that she hasn’t had her menstruation in 3 months, but had milky nipple discharge. Hormone serum measurements were performed in both, showing an increase in insulin-like growth factor-1 levels in Alex and an increase in prolactin levels in Maria.
Now, both seem to have a disease affecting the pituitary. But first, a bit of physiology. The pituitary is a small gland situated in a tiny bony space called the sella turcica. It is linked to the hypothalamus by the pituitary stalk, and it is divided into the anterior pituitary and the posterior pituitary. The posterior pituitary is not glandular; thus it doesn’t make its own hormones. Instead, it stores and secretes oxytocin and antidiuretic hormone which are produced in the hypothalamus. By contrast, the anterior pituitary has five types of hormone producing cells. First, lactotrophs secrete prolactin, which stimulates breast milk production and inhibits ovulation and spermatogenesis. Second, somatotrophs secrete growth hormone, or GH. GH acts directly on target tissues to stimulate growth and development. Then, corticotrophs secrete adrenocorticotropic hormone, or ACTH for short. ACTH makes the adrenal glands secrete cortisol. Cortisol is in charge of the stress response and keeping blood pressure and blood sugar in the normal range. Fourth, thyrotrophs secrete thyroid stimulating hormone, or TSH. TSH makes the thyroid gland release thyroid hormones, T3 and T4. Thyroid hormones speed up the basal metabolic rate in all cells, so it keeps cellular processes going at an optimal rate. And finally, gonadotroph cells secrete luteinizing hormone, or LH, and follicle-stimulating hormone, or FSH, that stimulate ovarian or testicular production of sex cells and sex hormones.