hypersecretion of anterior pituitary hormones Flashcards
(21 cards)
what is hyperpituitarism
Symptoms associated with excess production of adenohypophysial hormones
what is hyperpituitarism usually due to?
Usually due to isolated pituitary tumours but can also be ectopic (i.e. from non-endocrine tissue) in origin
what does excess of the following hormones lead to ? ACTH TSH LH/FSH Prolactin GH
cushings thyrotoxicosis precocious puberty in children hyperprolactinaemia gigantism, acromegaly
what is hyperprolactinaemia
too much prolacin
what are the causes of hyperprolactinaemia
physiological and pathological
Physiological
pregnancy
breastfeeding
Pathological
prolactinoma (often microadenomas < 10mm diameter)
Prolactinoma = most common functioning pituitary tumour
High prolactin suppresses GnRH pulsatility
what can hyperprolactinaemia due to pituitary adenoma cause in women?
galactorrhoea (milk production)
secondary amenorrhoea (or oligomenorrhoea)
loss of libido
infertility
what can hyperprolactinaemia due to pituitary adenoma cause in men?
galactorrhoea uncommon (since appropriate steroid background usually inadequate) loss of libido erectile dysfunction infertility
where is prolactin released from
anterior pituitary lactotroph
what does dopamine from hypothalamic dopaminergic neurons bind to and lead to?
dopamine binds to D2 receptors and blocks the release of prolactin
what is the treatment for hyperprolactinaemia
-with examples
Medical treatment is 1st line Dopamine receptor (D2) agonists Decrease prolactin secretion Reduce tumour size Examples: BROMOCRIPTINE CABERGOLINE Oral administration
what are the side effects of dopamine receptor agonists
Nausea and vomiting Postural hypotension Dyskinesias Depression pathological gambling
excess growth hormone in children and adulthood are called?
child = gigantism adult = acromegaly
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 (hyperhidrosis)
headache
enlargement of supraorbital ridges, nose, hands and feet, thickening of lips and general coarseness of features
enlarged tongue (macroglossia)
mandible grows causing protrusion of lower jaw (prognathism)
carpal tunnel syndrome (median nerve compression)
barrel chest, kyphosis
what are the metabolic effects of acromegaly
excess growth hormone
leads to increased endogenous glucose production, decreased muscle glucose uptake
leads to increased insulin production = increased insulin resistance
which then leads to impaired glucose tolerance
leading to diabetes mellitus
what are the complication of acromegaly?
-Obstructive sleep apnoea
Bone and soft-tissue changes surrounding the upper airway lead to narrowing and subsequent collapse during sleep
-Hypertension
Direct effects of GH &/or IGF-1 on vascular tree
GH mediated renal sodium reabsorption
-Cardiomyopathy
Hypertension, DM, direct toxic effects of excess GH on myocardium
-Increased risk of cancer
Colonic polyps, regular screening with colonoscopy
What is other hormone is co-secreted along with GH in acromegaly?
Prolactin is often high in acromegaly – may reflect tumour secreting GH AND prolactin
Hyperprolactinaemia will cause secondary hypogonadism (see clinical features of hyperprolactinaemia)
diagnosis of acromegaly -what can you use?
GH pulsatile – so random measurement unhelpful Elevated serum IGF-1 Failed suppression (‘paradoxical rise’) of GH following oral glucose load – oral glucose tolerance test
draw the graph to show the difference between normal and acromegalic response to glucose induced suppression of growth hormone secretion in acromegaly
acromegalic = increases normal = decreases
acromegaly= paradoxical rise in GH
what is the treatment of acromegaly?
Surgery (trans-sphenoidal) – 1ST LINE Medical Somatostatin analogues e.g. OCTREOTIDE Dopamine agonists (GH secreting pituitary tumours frequently express D2 receptors) e.g. CABERGOLINE Radiotherapy
what do somatostatin analogues do?
what are the side effects
‘Endocrine cyanide’
Injection: sc (short acting) or monthly depot
GI side effects common eg nausea, diarrhoea, gallstones can occur
Reduces GH secretion and tumour size
Pre-treatment before surgery may make resection easier
Use post-operatively if not cured or whilst waiting for radiotherapy to take effect (slow)
