Hypersecretion of Anterior Pituitary Hormones Flashcards
What is the usual cause of hyperpituitarism?
Pituitary tumours
But may be ectopic e.g. neuroendocrine tumour in gut
What visual defect is associated with pituitary adenoma?
Why?
Bitemporal hemianopia
Stretching optic chiasm + invading cavernous sinus
State the disease resulting from hypersecretion of:
a. Corticotrophin
b. Thyrotrophin
c. Gonadotrophin
d. Prolactin
e. Somatotrophin
Cortictrophin: Cushing’s disease Thyrotrophin: Thyrotoxicosis Gonadotrophins: Precocious puberty in children Prolactin: Hyperprolactinaemia Somatotrophin: Gigantism/Acromegaly
What is the usual cause of hyperprolactinaemia?
Prolactinoma
Most commonly microadenomas (< 10 mm)
State 5 symptoms of hyperprolactinaemia.
Loss of libido Infertility Galactorrhoea (rarely occurs in males) Oligomenorrhoea/amenorrhoea Erectile dysfunction
State 2 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 + respiratory problems
(mainly due to organ growth)
Cancer
State 8 common clinical features of acromegaly.
Headache Hyperhidrosis Prognathism Enlarged supraorbital ridges, nose, hands + feet Enlarged tongue Carpal tunnel syndrome General coarseness of features Barrel chest
What are the metabolic effects of GH?
Increased endogenous glucose production Decreased muscle glucose uptake Increased insulin production = increased insulin resistance Impaired glucose tolerance Diabetes Mellitus
What test is used to diagnose acromegaly and how are the results interpreted?
Glucose-induced suppression of GH secretion
Glucose load should cause a decrease in GH release in a normal individual
Acromegaly: Glucose load causes a paradoxical rise in GH release
State 4 treatments for acromegaly.
Trans-sphenoidal Hypophysectomy
Octreotide (somatostatin analogue)
Cabergoline (dopamine receptor agonists)
Radiotherapy
What are the clinical uses of octreotide?
Used short-term pre-surgery to shrink pituitary adenoma + GH secretion
Used long-term if it can’t be controlled by other means
State 3 side effects of octreotide.
Nausea
Diarrhoea
Rarely gallstones
What test is used if bitemporal hemianopia is suspected?
Perimetry test
What is the most common functioning pituitary tumour?
Prolactinoma
What does high prolactin suppress?
GnRH pulsatility, thus results in inability to make FSH + LH
What is the only pituitary hormone with inhibitory regulation? What causes this?
Prolactin
Dopamine binds to D2 receptors on lactotrophs, inhibits prolactin secretion
How is hyperprolactinaemia treated?
Dopamine receptor (D2) agonists (oral)
Decrease prolactin secretion
Reduce tumour size
Name 2 D2 agonists
Bromocriptine
Cabergoline (primarily used)
Name 6 side effects of D2 agonists
Nausea Vomiting Postural hypotension Dyskinesias Depression Pathological gambling
What is the most common cause of excess GH?
Benign GH secreting pituitary adenoma
Why does acromegaly often result in death?
Insidious at onset
Signs and symptoms progress gradually
What grows in acromegaly?
Periosteal bone Cartilage Fibrous tissue Connective tissue Internal organs
List 4 complications of acromegaly
Obstructive sleep apnoea
Hypertension
Cardiomyopathy
Increased risk of cancer
What may also be highly secreted in acromegaly? What results from this?
Prolactin
Causes secondary hypogonadism
