Hypersecretion of Anterior Pituitary Hormones Flashcards
What is the usual cause of hypersecretion of anterior pituitary hormones?
Pituitary adenoma
What visual defect is associated with pituitary adenoma?
Bitemporal hemianopia
State the disease resulting from hypersecretion of:
a. Corticotrophin
b. Thyrotrophin
c. Gonadotrophin
d. Prolactin
e. Somatotrophin
a. Cortictrophin Cushing’s disease b. Thyrotrophin Thyrotoxicosis c. Gonadotrophins Precocious puberty in children d. Prolactin Hyperprolactinaemia e. Somatotrophin Gigantism/Acromegaly
What is the usual cause of hyperprolactinaemia?
Prolactinoma
Most commonly microadenomas (< 10 mm)
State the symptoms of hyperprolactinaemia.
Loss of libido
Infertility
Galactorrhoea (rarely occurs in males as well) Oligomenorrhoea/amenorrhoea Impotence (in men)
State two physiological causes of hyperprolactinaemia.
Pregnancy
Breast feeding
What does excess growth hormone cause in children and in adults?
Children – gigantism
Adults – acromegaly
What are the most serious complications of excess growth hormone?
Cardiovascular problems (majority) and respiratory problems This is mainly due to organ growth
State some common clinical manifestations of acromegaly.
Prognathism Enlarged supraorbital ridges Enlarged soft tissue Hyperhydrosis Carpal tunnel syndrome (due to excessive cartilaginous growth) General coarseness of features Hypertension
What are the metabolic effects of acromegaly?
Increased insulin response to oral glucose leading to insulin resistance
This causes impaired glucose tolerance (in 50%) and diabetes mellitus (in 10%
What type of test is used to diagnose a hyperpituitary disorder?
Suppression test
What test is used to diagnose acromegaly and how are the results interpreted?
Glucose-induced suppression of growth hormone secretion
Giving glucose should cause a decrease in growth hormone release in a normal individual
In someone with acromegaly, giving glucose will cause a paradoxical rise in growth hormone release
State some of the treatments for acromegaly.
Transsphenoidal Hypophysectomy Radiotherapy Chemotherapy: Octreotide (somatostatin analogue) Bromocriptine and Cabergoline (dopamine receptor agonists)
What are the clinical uses of octreotide?
It can be used short-term before surgery to shrink the size of the pituitary adenoma
It can be used long-term if it can’t be controlled by other means
It is used as a treatment for other neuroendocrine tumours e.g. carcinoid tumours
Describe the administration, distribution and metabolism of octreotide.
Octreotide is administered SC or IM 3/day
It is retained in extracellular fluid
Half-life = 2-4 hours