🧠 Endocrine System Lesson

FLAT PiG: the six anterior pituitary hormones

The anterior pituitary is the "master gland" for a reason — its six hormones control nearly every other endocrine gland in the body.

FSH

ACTH

TSH

Prolactin

📖 Full Breakdown

Six hormones, six downstream targets

Four of these six are "tropic" hormones — meaning their entire job is to stimulate another gland further down the chain.

FSH

Follicle Stimulating Hormone

Stimulates follicle development in females and spermatogenesis in males.

Luteinizing Hormone

Triggers ovulation in females; stimulates testosterone production in males. A sharp LH surge around day 14 of the menstrual cycle triggers ovulation.

ACTH

Adrenocorticotropic Hormone

Stimulates the adrenal cortex to produce cortisol — elevated ACTH is a hallmark of Cushing's disease (a pituitary tumor overproducing ACTH).

TSH

Thyroid Stimulating Hormone

Stimulates the thyroid to produce T3/T4 — a high TSH with low T4 indicates the thyroid itself isn't responding (primary hypothyroidism).

Prolactin

Milk production

The only one of the six that is NOT a tropic hormone aimed at another gland — it acts directly on breast tissue.

Growth Hormone

Stimulates growth and IGF-1 production. Excess in adults causes acromegaly; deficiency in children causes dwarfism.

🩺 Clinical / Exam Application

A patient has lab results showing high TSH and low T4. Because TSH is a tropic hormone whose entire job is to stimulate the thyroid, a high TSH paired with a low T4 tells you the pituitary is working correctly and trying harder to stimulate a thyroid that isn't responding — this pattern specifically identifies primary hypothyroidism (the problem is IN the thyroid, not upstream in the pituitary).

⚠️ Exam Alert

A commonly tested clarification: the posterior pituitary does NOT produce ADH or oxytocin — it only stores and releases hormones that are actually made in the hypothalamus. Exam questions often test whether you know this distinction rather than assuming the posterior pituitary "makes" hormones the way the anterior does.

🚧 Common Trap

Don't assume all six anterior pituitary hormones work the same way. Prolactin acts directly on target tissue (breast), while FSH, LH, ACTH, and TSH are all "tropic" — meaning their job is entirely to stimulate a downstream gland to produce a different hormone.

✅ Quick Check

Which anterior pituitary hormone is not a "tropic" hormone aimed at another gland, and what does it act on directly?

📝 Exam Prep

Common Exam Questions

❓ What is the difference between the anterior and posterior pituitary?

✅ The anterior pituitary produces its own hormones (GH, TSH, ACTH, FSH, LH, Prolactin). The posterior pituitary stores and releases hormones made in the hypothalamus (ADH and Oxytocin).

❓ What does elevated ACTH suggest, and what condition is it classically associated with?

✅ Elevated ACTH stimulates the adrenal cortex to overproduce cortisol. It is classically associated with Cushing's disease, caused by a pituitary adenoma overproducing ACTH.