Endo 2 - Hypersecretion of APG Hormones Flashcards
What is hyperpituitarism?
Symptoms associated with excess production of APG hormones
What can cause hyperpituitarism?
Pituitary tumour
Can also be ectopic (ectopic = non-endocrine tissue)
What is hyperpituitarism often associated with?
Visual field defects (& cranial nerve defects)
What is the optic chiasm?
The place where the fibres of the nasal retinae cross.
Compression of Optic chiasm = loss of temporal fields of vision
Excess ACTH (corticotrophin) can cause?
Cushings disease
Excess TSH (thyrotrophin) can cause?
Thyrotoxicosis
Excess LH/FSH (gonadotrophins) can cause?
Precocious puberty in children
Excess prolactin can cause?
Hyperprolactinaemia
Excess GH can cause?
Gigantism (children/teenagers) or acromegaly (adults)
Physiological reasons why prolactin may be high?
Pregnancy or breastfeeding
Pathological reasons why prolactin may be high?
Prolactinoma (micro adenoma in the pituitary - <10mm)
What is the most common functioning pituitary tumour?
Prolactinoma
What can high prolactin levels suppress?
High prolactin suppresses GnRH pulsatility - potentially causing secondary hypogonadism
How can hyperprolactinaemia present in women?
- Galactorrhoea (milk production outside of lactation)
- Secondary amenorrhoea (or oligomenorrhoea)
- Loss of libido
- Infertility
What is oligomenorrhoea?
Infrequent periods
What is secondary amenorrhoea?
When menstruation has started then it switches off
How can hyperprolactinaemia present in men?
- Infertility
- Erectile dysfunction
- Loss of libido
- Galactorrhoea uncommon (men don’t have enough oestrogen usually to prime the breast)
What is secreted by the hypothalamus that inhibits prolactin secretion?
Dopamine.
How can hyperprolactinaemia be treated?
D2 receptor agonist
Usually, pituitary tumours involve neurosurgeons, etc to treat. What is different about a prolactinoma.
Medical treatment is first line. D2 receptor agonists decrease prolactin secretion and reduce tumour size
Name 2 D2 receptor agonists.
- Bromocriptine
2. Cabergoline (1st line D2 receptor agonist - taken 1/2 a week for 3 years)
What are the side effects of D2 receptor agonists?
- Nausea and vomiting (moreso Bromocriptine)
- Postural hypotension
- Dyskinesias
- Depression
What is excess GH usually due to?
Benign pituitary adenoma which secretes GH
Is acromegaly identified easily?
No.
It can be insidious in onset and also signs and symptoms progress gradually.
Untreated, excess GH can cause increased morbidity and mortaility
Excess GH can cause?
CV Disease
Respiratory complications
Cancer
What grows in acromegaly?
- Periosteal bone
- Cartilage
- Fibrous tissue
- Connective tissue
- Internal organs (cardiomegaly, splenomegaly, hepatomegaly, etc)
What are the clinical features of acromegaly?
- Excessive sweating
- Headache
- General coarseness of features (e.g. nose, hands and feet bigger, lips thicken), enlargement of supraorbital ridges
- Enlarged tongue
- Mandible grows (protrusion of lower jaw)
- Carpal tunnel syndrome (can squash median nerve)
- Enlarge chest
What are the metabolic effects of acromegaly?
Excess GH causes increased endogenous glucose production & decreased muscle uptake. This means increased insulin production which increases insulin resistance - causing impaired glucose tolerance and predisposition to T2DM
What are the complications of acromegaly?
- Increased cancer risk (e.g. colonic cancer - screening done)
- Obstructive sleep apnoea - bone/soft tissue changes surrounding upper airway causes narrowing/collapse during sleep
- Hypertension (GH/IGF-1 directly on vascular tree / GH mediated renal sodium absorption)
- Cardiomyopathy - hypertension, DM, toxic effects of excess GH on myocardium
Acromegaly often involves co-secretion of what hormone in addition to GH?
Prolactin.
Hyperprolactinaemia will cause secondary hypogonadism
What is the gold standard in diagnosing acromegaly?
“paradoxical rise” in GH following oral glucose load (GH should actually decrease)
How is acromegaly treated?
- Surgery (trans-sphenoidal) - FIRST LINE
- Medical -
Somatostatin analogue (e.g. Octreotide) / D2 receptor agonists (e.g. cabergoline) - Radiotherapy (can be slow)
Somatostatin analogues may cause side-effects in?
The GI system. Nausea, diarrhoea, gallstones may occur
