Hormonal Evaluation in Pituitary Tumours

The pituitary gland is known as the "orchestra conductor" of the body; it secretes hormones that control vital functions such as growth, metabolism, reproduction, stress response, and water balance. Hormonal evaluation in pituitary tumours is the cornerstone of diagnosis and treatment planning.

Pituitary Hormones and Target Organs

The anterior pituitary secretes six main hormones. Prolactin stimulates the mammary glands, growth hormone (GH) stimulates growth in bones and muscles, ACTH stimulates the adrenal glands, TSH stimulates the thyroid gland, and FSH and LH stimulate the gonads (ovaries/testicles). The posterior pituitary secretes ADH (water balance) and oxytocin (childbirth/breastfeeding).

Prolactinoma

It is the most common functional pituitary adenoma.^1,2 In women, amenorrhea (absence of menstruation), galactorrhea (milk production), and infertility are seen; in men, decreased libido, erectile dysfunction, and gynecomastia are seen. In diagnosis, serum prolactin level is measured; values over 200 ng/mL strongly suggest prolactinoma.^3,4 Dopamine agonists (cabergoline, bromocriptine) are the first line of treatment.^5,6

Diagnosis is complex; 24-hour urine cortisol, late-night salivary cortisol, and low-dose dexamethasone suppression tests are used.

Acromegaly (GH Adenoma)

Growth hormone excess causes acromegaly in adults. Enlargement of the hands, feet, and facial features, joint pain, increased sweating, sleep apnoea, and diabetes may develop. In diagnosis, GH level and IGF-1 are measured; the oral glucose tolerance test is the gold standard.^7,8 Transsphenoidal surgery is the first line of treatment; somatostatin analogs (octreotide, lanreotide) are used as adjunctive therapy.^9,10

Cushing's Disease (ACTH Adenoma)

ACTH-secreting adenomas lead to Cushing's disease. Central obesity, round face (moon face), purple striae, osteoporosis, hypertension, and diabetes are typical findings. Diagnosis is complex; 24-hour urine cortisol, late-night salivary cortisol, and low-dose dexamethasone suppression tests are used. Inferior petrosal sinus sampling is important in excluding ectopic ACTH sources.^11,12 Transsphenoidal surgery is the standard treatment.^13,14

TSH Adenoma

It is rarely seen (1-2 percent).¹⁵ It creates a picture of secondary hyperthyroidism. Thyroid hormones are observed to be high, and TSH is unsuppressed (inappropriately high).

Non-functioning Adenomas

Non-hormone-secreting adenomas have an insidious course. By growing, they can compress the optic chiasm and cause vision loss, or compress healthy pituitary tissue and cause hypopituitarism (hormone deficiency). In these patients, a comprehensive evaluation of all pituitary hormones is required before and after surgery.

→ Next page: S18 — Acoustic Neuroma