Pituitary Disorders

Core Concepts

The anterior pituitary: the conductor of the hormone orchestra

Each anterior pituitary hormone controls a downstream target, and each runs on the same "chain of command": the hypothalamus releases a releasing (or inhibiting) factor → the anterior pituitary releases its hormone → the target gland releases its hormone → rising levels feed back to quiet the system. The main lines:

• GH → growth and metabolism, acting on tissues throughout the body.
• TSH → the thyroid (see Thyroid and Parathyroid Disorders).
• ACTH → the adrenal cortex, mainly cortisol (see Adrenal Disorders).
• FSH and LH → the ovaries and testes (reproduction and sex hormones).
• Prolactin → milk production.

Because each line has its own feedback, a pituitary problem can mimic a thyroid problem, an adrenal problem, or a reproductive problem — the nurse's history and the pattern of which hormones are affected help point upstream.

The posterior pituitary: storage for hypothalamic hormones

ADH and oxytocin are made in the hypothalamus, travel down the stalk, and are released from the posterior pituitary. ADH tells the kidney's collecting ducts to reabsorb water, concentrating the urine and protecting blood volume. Oxytocin triggers uterine contractions in labor and milk let-down during breastfeeding. When this system fails, the result is a water-balance disorder, not a "gland failure" in the usual sense.

Hypopituitarism: the quiet gland

Hypopituitarism means one or more anterior (and sometimes posterior) pituitary hormones are missing. Causes include pituitary adenomas compressing the normal gland, surgery, radiation, head trauma, reduced blood flow — including Sheehan syndrome, pituitary damage after severe postpartum hemorrhage — infections, and infiltrative diseases. Which hormones are lost determines the picture: loss of TSH produces secondary hypothyroidism; loss of ACTH produces secondary adrenal insufficiency (which can be dangerous because cortisol is needed to handle stress); loss of FSH/LH causes menstrual changes and reduced libido; loss of GH causes growth failure in children and fatigue in adults. Onset is often gradual, so the presentation can be vague: fatigue, low blood pressure, cold intolerance, and weight change. Treatment is replacement of the specific missing hormones — always provider-directed, with dosing individualized.

Hyperpituitarism: too much of a good thing

Most pituitary tumors (adenomas) are benign but hypersecrete one hormone. Common patterns:

• GH excess → gigantism if it begins in childhood before growth plates close (tall stature with proportionally large bones), or acromegaly in adulthood: enlarged hands and feet, coarse facial features, thickened skin, joint pain, headache, and sweating. (Cardiac and metabolic effects are possible — see current evidence.)
• Prolactin excess → breast milk production outside of breastfeeding (galactorrhea), menstrual irregularity, and lowered libido.
• ACTH excess → Cushing disease, a pituitary-driven form of cortisol excess (link to Adrenal Disorders).
• TSH excess → rare secondary hyperthyroidism.

Mass effects: what the tumor presses on

An enlarging pituitary adenoma compresses normal gland tissue (causing hypopituitarism — so a patient can have both too much of one hormone and too little of others) and presses on structures nearby. The classic consequence is pressure on the optic chiasm, where the optic nerves cross just above the pituitary, producing bitemporal hemianopsia — loss of the outer (temporal) half of the visual field in both eyes. Headache is common. The evaluation is provider-driven and typically involves a careful history, visual field testing, hormone levels, and imaging.

The posterior syndromes: ADH too low or too high

• Diabetes insipidus (DI) — too little ADH. The kidneys cannot concentrate urine, so the person produces large volumes of very dilute urine (polyuria) and is intensely thirsty (polydipsia). If the person cannot keep up with fluid intake, dehydration and dangerously high blood sodium can follow. DI is a classic complication of pituitary surgery and head trauma, and it can be temporary or permanent. Nursing focus: accurate intake and output, urine concentration checks per policy, and hydration monitoring.
• SIADH (syndrome of inappropriate antidiuretic hormone) — too much ADH activity. The kidneys hold onto water, diluting the blood and lowering sodium (hyponatremia). Early effects are subtle — headache, nausea, confusion, muscle cramps — but severe hyponatremia can cause seizures and altered consciousness. Causes include some cancers (which make ADH-like substances), lung disease, central nervous system disorders, and certain medications. Nursing focus: careful fluid balance, neurologic checks, and seizure precautions, with fluid management per provider orders.

Clinical Scenario

Ms. Alvarez, 38, had a transsphenoidal hypophysectomy (removal of a pituitary adenoma through the nose and sphenoid sinus) three days ago for a tumor causing visual field loss. Overnight her urine output climbs to very large volumes; the nurse notes it is very pale/dilute and Ms. Alvarez keeps asking for water. The nurse's reasoning: pituitary surgery can temporarily disrupt ADH release → the kidneys stop concentrating urine → diabetes insipidus. She documents hourly output, checks urine concentration per unit protocol, and notifies the provider, who adjusts the plan. The nurse also knows the pendulum can swing the other way: later in the post-operative course, SIADH can appear, so she continues neurologic checks and watches for headache, nausea, or confusion. She checks the nares dressing for clear drainage (a possible cerebrospinal fluid leak) per policy and reminds Ms. Alvarez not to cough, blow her nose, or bend forward without staff guidance. Everything here is recognition, monitoring, and reporting — diagnosis and treatment remain provider- and institution-driven.

Common Confusions