Hypersecretion of anterior pituitary hormones Flashcards
Lecture is different from notes
Define hyperpituitarism
Symptoms associated with excess production of adenohypophysial hormones.
Isolated pituitary tumours, can also be ectopic in origin. Associated with visual field defects and other CN defects.
What happens when the optic chiasm is compressed?
Bitemporal hemianopia
See diagram. Light from the temporal part of the visual field strikes the nasal aspect of the retina. Hence if the pituitary tumour protrudes out of the sella turcica it compresses on the optic chiasma
What does excess anterior pituitary hormones cause?
Cushing’s disease, Thyrotoxicosis, Precocious puberty in children, hyperprolactinaemia, gigantism, acromegaly
What are the phsyiological and pathological causes of hyperprolactinaemia?
Physiological - Breast feeding and pregnancy
Pathological - Pituitary tumour; prolactinoma (often microadenomas <10mm diameters)
Hypoprolactinaemia isn’t usually a problem - there are no physiological consequences
What does high prolactin cause?
It suppresses GnRH pulsality - which causes descrease in LH and FSH leading to secondary ammenorrhoea
What symptoms does hyperprolactinaemia (as a reult of a pituitary tumour) cause?
Women - galactorrhoea, secondary amenorrhoea (or oligomenorrhoea), loss of libido, infertility
Men - galactorrhoea (usually uncommon as the steroid background is inadequate), loss of libido, erectile dysfunction, infertility
Apart from glactorrhoea all of the other effects are caused by the decrease in levels of LH and FSH which are caused by the high levels of prolactin.
How can you treat the hyperprolactinaemia?
Dopamine from hypothalamic dopaminergic neurones can bind to D2 receptors which prevent the production of prolactin. By using a D2 receptor agonist the same effect can be produced.
Cabergoline, bromocriptine - oral
Aim is to decrease prolactin secretion and reduce tumour size
What are the side effects of D2 dopamine receptor agonists?
Nausea vomiting Postural hypotension Dyskinesias Depression Pathological gambling
What does excess GH cause?
Children - gigantism
Adults - acromegaly
Describe acromegaly?
See notes
What grows in acromegaly
Periosteal bone Cartilage Fibrous tissue Connective tissue Internal organs (cardiomegaly, splenomegaly, hepatomegaly etc) - growth in organs means increase demand for oxygen which puts strain on CVS.
What are the clinical features of acromegaly
Excessive sweating (hyperhidrosis)
Headache
Enlargement of supra orbital 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 GH –> Increased endogenous glucose production and decreased muscle glucose uptake –> Increased insulin production = increased insulin resistance –> impaired glucose tolerance –> diabetes mellitus
What are the complications of acromegaly?
Obstructive sleep apnoea
Hypertension
Cardiomyopathy
Increased risk of cancer
What hormone is often secreted along side GH in acromegaly?
Prolactin - causes hyperprolactinaemia –> secondary hypogonadism
