Hypopituitarism

Question 1

Definition

Answer 1

Deficiency in one or more of the hormones secreted by the anterior pituitary. Panhypopituitarism is deficiency of ALL pituitary hormones.

Question 2

Aetiology/Risk factors

Answer 2

· Pituitary Masses
o Most commonly adenomas
o Others include craniopharyngioma, meningioma, glioma, metastases
o Cysts

· Pituitary Trauma - radiation, surgery, base of skull fractures

· Hypothalamic Dysfunction - due to anorexia, starvation, over-exercise

· Infiltrative Diseases - sarcoidosis, haemochromatosis, Langerhans’ cell histiocytosis

· Vascular - pituitary apoplexy, Sheehan’s syndrome

· Infection - meningitis, encephalitis

· Genetic Mutations - Pit-1 and Prop-1 genes

Question 3

Epidemiology

Answer 3

Pituitary adenoma annual incidence: 1/100,000

Question 4

Presenting symptoms and signs on physical examination

Answer 4

· Depends on CAUSE

· Symptoms and signs are dependent on the hormone that is deficient:

o GH
· CHILDREN: short stature
· ADULTS: low mood, fatigue, reduced exercise capacity and muscle strength, increased abdominal fat mass

o LH or FSH
· Delayed puberty
· FEMALES: loss of secondary sexual hair, breast atrophy, menstrual irregularities, dyspareunia, decreased libido, infertility
· MALES: loss of secondary sexual hair, gynaecomastia, small and soft testes, decreased libido, impotence

o ACTH - signs/symptoms of adrenal insufficiency

o TSH - signs/symptoms of hypothyroidism

o Prolactin - absence of lactation (not usually noticed clinically)

Question 5

Presenting symptoms and signs on physical examination (pituitary apoplexy)

Answer 5

o Headache

o Visual loss

o Cranial nerve palsies

Question 6

Investigations

Answer 6

Pituitary Function Tests

o Basal Tests
· 9 am cortisol
· LH and FSH levels
· Testosterone levels
· Oestrogen levels
· IGF-1 levels
· Prolactin levels
· Free T4 and TSH levels

o Dynamic Tests (rarely performed)
· Insulin-induced hypoglycaemic (should cause a rise in GH and cortisol)

o Short synacthen test (for adrenal insufficiency)

o MRI/CT of brain

o Visual field testing

Question 7

Management plan

Answer 7

· Hormone Replacement

o Hydrocortisone

o Levothyroxine

o Sex hormones
· Testosterone in males
· Oestrogen with/without progesterone in females
· Growth hormone
· Desmopressin (if central diabetes insipidus as a result of panhypopituitarism)

Question 8

Possible complications

Answer 8

· Addisonian crisis

· Hypoglycaemia

· Myxoedema coma

· Infertility

· Osteroporosis

· Dwarfism (children)

· Complications of pituitary mass:
o Optic chiasm compression (leading to bitemporal hemianopia)
o Hydrocephalus
o Temporal lobe epilepsy

Question 9

Prognosis

Answer 9

GOOD prognosis with lifelong treatment