Pituitary Disease Flashcards
What is the hypothalamus
- coordinating centre for endocrine centre
- inputs from upper cortical parts, autonomic function, environ cues, peripheral endocrine feedback
- delivers signals to pituitary via stalk = hormone release influencing target organ
- ant. pituitary connected via portal system so high levels of hormones reaching pituitary
- anterior and posterior pituitary
Pituitary gland anatomy
- outside dura
- in sella turcica
- below optic chiasm
- anterior and posterior gland
- behind eyes
- accessed through sphenoid bones
Anterior pituitary
- rich blood supply (capillary plexus) with high releasing hormones
- ACTH
- TSH
- GH
- LH/FSH
- PRL
Posterior pituitary
- inferior hypophyseal artery supplies
- drains into inf hypophyseal veins into systemic circ
- ADH
- oxytocin
Hormone excess and deficiency syndromes
GH = acromegaly, deficiency PRL = hypogonadism, failed lactation FSH/LH = rare, hypogonadism ACTH = cushing's, adrenal insufficiency TSH = hyperthyroidism, hypothyroidism ADH = SIADH, diabetes insipidus
Effect of pituitary tumours
- tumour = releases more hormone = excess
- non functioning tumour = presses on working structures of pituitary = don’t produce enough = deficiency
Hormone hypersecretion
- prolactinoma = amenorrhoea/galactorrhoea
- acromegaly
- cushing’s
- thyrotoxicosis (2ndry) (excess TSH) (v. rare)
Symptoms from pituitary mass
- headaches
- vision loss
- pituitary gland hyposecretion
- pituitary apoplexy
How to classify pituitary tumours
Microadenoma = <1cm Macroadenoma = 1cm or more
Prolactinoma = symptoms, signs, invest, management
- commonest functioning pituitary adenoma
- SYMP = amennorhoea, galactorrhoea, ED, sight loss as chiasmal compression
- SIGNS = galactorrhoea, hypogonadism, bitemporal hemianopia
- INVEST = prolactin, TFT, LH, FSH, testosterone, MRI pituitary
- MANAGEMENT = dopamine agonist as prl release inhibition (bromocriptine, cabergoline)
Other causes of hyperprolactinaemia
- lactation/pregnancy
- drugs = antacids, anti-psychotics, anti-emetics (block dopamine)
- stress
- seziures
- stalk compression
- macroprolactin (produce larger form of prolactin so seems as if elevated but actually normal levels and no physiological effect)
GH excess 2 types
- gigantism = before puberty, before closure of growth plate
- acromegaly = after puberty, after completion of linear growth
Acromegaly symptoms
- triad = headaches, sweating, arthralgia
+ increased ring/shoe signs, weakness, diabetes, carpal tunnel, atherosclerosis, increased risk of cancer as IGF-1 excess = colorectal cancer
Acromegaly signs
- spade hands
- prominent supraorb ridge
- prognathism (large and forward facing jaw)
- bitemporal hemianopia
- hypertension
- wide spaced teeth
Investigations for acromegaly
- OGTT as GH should suppress with glucose, fast patient and check levels, then 75g glucose, GH should fall but if failure to suppress GH = positive
- , IGF-1 (non diagnostic, response to treatment test)
- MRI pituitary
Treatment for acromegaly
- octreotide (somatostatin analogue, injection 1 a month)
- pegvisomont (GH receptor antagonist, if octreotide not responsive)
- trans phenoidal surgery
Cushing’s syndrome 2 types and causes
ACTH dependent 75% - corticotroph adenoma (Cushing's) - ectopic cushings (ACTH/CRH tumours) ACTH independent (25%) - adrenal carcinoma - adrenal adenoma - exogenous steroids (cushingoid appearance)
Symptoms of Cushing’s
CHO/Protien/Fat Met - central obesity/moon faces, fat pads - osteoporosis - diabetes - hypertriglycaemia - peripheral wasting of fat/muscle SEX HORMONES - amenorrhoea/infertility - excess hair growth - impotence SALT AND WATER RETENTION - HTN and oedema
IMPAIRED IMMUNITY
NEUROCOGNITIVE CHANGES
Signs of Cushing’s
plethoric face purple stretch marks thin skin moon face central obesity
Cushing’s screening tests
- disrupted circadian rhythm = should be midnight serum/salivary cortisol low, day curve, morning cortisol surge (not diagnostic)
- 24 hour urine free cortisol = increased load?
- MAIN ONE, SCREENING = low dose dexamethasone suppression test, 1mg, should suppress adrenals for 24-48 hours completely, if Cushing’s failure of suppression, measure cortisol and ACTH
Cushing’s management
- trans-sphenoidal surgery
- ketoconazole = anti-fungal, stops steroid pathway and adrenolytic
- metyrapone = side effects but adrenolytic preventing excess cortisol, good to get fitter prior to surgery
Hypopituitarism define
- loss of all or some pituitary hormones, usually anterior
Causes of hypopituitarism
Adenoma
Irradiation
Infarction (sheehan’s)(post childbirth)
- infiltration (sarcoid, TB)
Symptoms of hypopituitarism
Loss of libido Weakness Amenorrhoea Impotence Depression Hypothyroidism
Signs of hypopituitarism
Pallor Hypothyroid Absent pubic/axillary hair testicular atrophy visual field defect postural hypotension
Investigations of hypopituitarism
insulin stress test
low T4 test
MRI pituitary
Treatment of hypopituitarism
HRT = hydrocortisone then T4 then testosterone
- ovulation induction
Pituitary Apoplexy
- abrupt acute haemorrhagic infarction of pituitary adenoma
- presents = acute headache, meningism, visual impairment, ophthalmoplegia, low GCS
- glucocorticoid replacement!! as adrenal insufficiency
- then surgical decompression
