Endocrinology 2- Hypersecretion of Anterior Pituitary Hormones Flashcards
What is hyperpituitarism?
- Symptoms associated with excess adenohypophysial hormones, with visual field defects (bitemporal hemianopia) and endocrine related signs and symptoms
- Usually due to pituitary tumours but can be ectopic
What is the cause of bitemporal hemianopia?
Pituitary adenomal compresses the optic chiasm, affecting the visual field (cant see the outer field of each eye), crushes the nerve innervating the nasal part of retina
What are the possible results in hyperpituitarism?
- Excess ACTH can result in Cushings disease
- Excess TSH can result in thyrotoxicosis
- Excess gonadotrophins can result in early puberty
- Excess prolactin can result in hyperprolactinoma and suppressed GnRH release
- Excess GH can result in gigantism or acromegaly
List the causes of hyperprolactinaemia
- Physiological (pregnancy and brestfeeding)
- Pathological (prolactinoma)
List the symptoms of hyperprolactaemia due to pituitary adenoma in women
- Galactorrhoea
- Secondary amenorrhoea
- Loss of libido infertility
List the symptoms of hyperprolactaemia due to pituitary adenoma in men
- Galactorrhoea is uncommon
- Loss of libido
- Erectile dysfunction
- Infertility
How can hyperprolactinaemia be treated?
- Dopamine receptor (D2) agonist decreases prolactin secretion and reduces tumour size
- Eg. bromocriptine and cabergoline
List the side affects of dopamine receptor agonists
- Nausea and vomiting
- Postural hypotenstion
- Dyskinesias
- Depression
- Impulse control disorder (eg. Gambling)
What is the result of undiagnosed excess GH?
- Signs and symptoms progress gradually (insidious)
- Increased morbidity and mortality
- Death due to cardiovascular disease (60%), respiratory (25%) cancer (15%)
In acromegaly what grows?
- Periosteal bone
- Cartilage
- Fibrous tissue
- Connective tissue
- Interal organs
List the symptoms 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
Describe the metabolic effects of acromegaly and gigantism
- Increased endogenous glucose production and decreased muscle glucose uptake
- Increased insulin production and resistance
- Impaired glucose tolerance
- Diabetes mellitus
List the complications of acromegaly
- Obstructive sleep apnoea (changes in upper airway leading to narrowing)
- Hypertension (effects of GH and IGF1 on vascular tree and renal sodium reabsorption)
- Cardiomyopathy (hypertension, diabetes and GH directly)
- Increased cancer risk (colonic polyps)
What hormone is often also high in acromegaly?
- Prolactin
- Causes secondary hypogonadism
How is acromegaly diagnosed?
- GH pulsatile so random measurement is unhelpful
- Elevated serum IGF 1
- Failed suppression of GH following oral glucose load (glucose tolerance test - paradoxial rise)
