Hypersecretion Of Pituitary Hormone

Question 1

Define hyperpituitarism, bitemporal hemianopia and what syndrome is caused by what hyper secretion

Answer 1

Hyperpituitarism: symptoms associated with excess production of adenohypophysial hormones, usually due to isolated pituitary tumours but can also be ectopic (ie from non endocrine tissue) can often be associated with visual fields and other cranial defects

Bitemporal hemianopia: pituitary tumour producing sella turcia and disrupts fibres, at the optic chiasm, the fibres from the inner part of both retinae cross.

Hyperpituitarism:

1. ACTH > cushings
2. TSH > thyrotoxicosis
3. Gondadotrophins (LH FSH) > precocious puberty in children
4. Prolactin > hyperprolactinaemia
5. Somatotropin (GH) > gigantism and acromegaly

Question 2

Describe what prolactinaemia and its symptoms and treatment

Answer 2

Hyperprolactinaemia: physiologically normal when pregnant (breastfeeding) but when prolactinoma = high prolactin suppresses GnRH pulsatility so less LH and FSH

Symptoms in women: galactorrhea (milk production), secondary amenorrhea, loss of libido, infertility. Men: galactorrhea, loss of libido, erectile dysfunction, infertility.

Regulation of prolactin secretion: anterior pituitary lactotroph secretes prolactin - dopamine from hypothalamic dopaminergic neurone - D2 receptor (inhibit prolactin secretion). Therefore medical treatment is bromocripine and cabergoline (dopamine receptor agonist)

Question 3

Describe the effects of excess somatotrophin, clinical features, complications, diagnosis and treatment.

Answer 3

Excess somatotrophin in childhood is gigantism, and in adulthood is acromegaly (usually benign adenoma)

Acromegaly: insidious effect - cardiac myopathy, respiratory complication, bowel cancer, increased growth of perrosteal bone, cartilage, fibrous tissue, internal organs. Metabolic effect: increased plasma insulin and impaired glucose tolerance test (DM)

Symptoms: hyperhidrosis, headache, enlargement of nose, hand feet, macroglossia

Complications: obstructive sleep apnoea, hypertension, cardiomyopathy

Diagnosis: elevated serum IGF-1 failed suppression after oral glucose because GH should decrease

Treatment: surgery, medication (somatostatin analogues Eg octreotide) dopamine antagonist (cabergoline)