Pituitary Diseases Flashcards
How can pituitary tumours be classified?
Microadenomas < or = 1cm
Macroadenomas > or = 1cm
functioning or non-functioning
What pituitary tumours are unlikely to present?
Small non-functioning tumours as unlikely to be producing any large amount of symptoms
What can large non-functioning pituitary tumours produce….
pressure effects or hormone deficiencies (hypo-pituitary)
Describe presentation of large non-functioning pituitary tumour?
LOCAL ANATOMICAL EFFECTS:
- bitemporal hemianopia
- damage to CN 2,3,4,5 and 6
- damage/ pressure on bony structures and meninges surrounding the fossa causing a headache
- pressure on hypothalamic centres causing altered appetite, obesity, thirst, somnolence/ wakefulness or precocious puberty
- interuption of CSF and CSF leak from nose
DEFICIENCIES OF HORMONES:
- usually affects the anterior pituitary
- hypothyroidism, hypogonadism, GH deficiency, hypoadrenalism
- unlikely diabetes insipidus
What must you check in someone with a pituitary tumour before operating?
Serum prolactin
What is prolactinoma?
Prolactin secreting adenoma of the pituitary gland
Presentation of prolactinoma?
Tends to present much earlier in women due to the nature of the symptoms: galactorrhea (lactation when not been pregnant), amenorrhoea and infertility
In men: impotence, visual field defects and headaches (as not noticed till large) and anterior pituitary malfunction
Who do prolactinomas tend to present earliest in?
Young women
Other than a prolactinoma what else can cause a rise in serum prolactin?
Physiological: breast feeding, pregnancy, stress and sleep
Drugs: dopamine antagonists e.g. metoclopramide, anti psychotics, antidepressants, oestrogen and cocaine
Pathological: Hypothyroid and stalk lesions
Why is it important to know about illicit drug use if high serum prolactin?
Cocaine can cause increase in serum prolactin
If serum prolactin is over _____ almost certainly a prolactinoma
5000
Investigations for prolactinoma?
serum prolactin and MRI pituitary
PREGNANCY TEST!!!
Pituitary function tests for other hormones affected
Treatment of prolactinoma?
Dopamine agonists are very effective and cause tumour shrinkage
Tend to use cabergoline
What causes acromegaly and gigantism?
Growth hormone excess
Almost all cases of acromegaly and gigantism are due to….
GH producing pituitary tumour- somatotroph adenoma
Usually occurs sporadically but gene mutations can give rise to familial forms
Describe gigantism and its features
Occurs in children before epiphyses have fused, execs GH stimulates hepatic secretion of ILGF-1. There is excess skeletal growth with bones retaining normal shape and relative proportions. Fusion of epiphysis is delayed but eventually occurs and features of acromegaly appear.
Describe acromegaly and its features?
Overgrowth of bone and soft tissue.
Features coarsened, enlarged nose
Projecting jaw
Irregular bone formation interferes with joints so get OA
Enlarged hands and feet
Pain from nerve compression
High BP with cardiac hypertrophy and may die of cardiac failure
2/3 fold increased risk of colonic cancer
Sleep apnoea
Investigations for acromegaly and gigantism?
Check IGF-1 Definitive test is glucose tolerance as normally should get suppression of GH but in acromegaly it will be unchanged Check MRI Check visual field Check other hormone functions
Definitive test for acromegaly?
Glucose tolerance as normally should get suppression of GH but in acromegaly it will be unchanged (as growth hormone counteracts blood glucose control of insulin so normally you would expect it to decrease in high blood glucose to allow insulin to do its job)
Describe the relationship between growth hormone and insulin?
Growth hormone (GH) counteracts in general the effects of insulin on glucose and lipid metabolism, but shares protein anabolic properties with insulin
Treatment of acromegaly and gigantism?
Trans-sphenoidal surgery is 1st line in most cases.
Patients with residual disease are offered drug treatment (somatostatin analogue> OCREOTIDE) to reduce GH and shrink tumour
Radiotherapy is last resort
Screening- cancer, CV risk factors, sleep apnoea
Which type of lung cancer can secrete ADH? How does this present?
Small cell lung cancer
Dilutional hyponaetremia
Which type of lung cancer can secrete ACTH causing Cushing’s syndrome?
Small cell lung cancer
Which type of lung cancer can cause hypercalcaemia and how? How does this present?
Squamous cell secretes parathyroid mimicking hormone so calcium is secreted. Will have a high serum calcium but undetectable parathyroid hormone.
Which type of lung cancer is most likely to have non-metastatic effects and why?
Small cell lung cancer as it arises from neuroendocrine cells.
Define cushing’s syndrome
Clinical state of increased free circulating glucocorticoid (cortisol)
Causes of cushing’s syndrome?
Majority are due to pituitary disease (cushing’s disease)
Second commonest is benign adenoma or the adrenal gland
Ectopic ACTH production from tumours (e.g. SCLC and pancreatic)
What does cushing’s disease refer to?
Specifically pituitary driven cushing’s syndrome
Majority cases of cushing’s syndrome are due to …
pituitary disease
Clinical features of cushing’s syndrome?
thin skin, bruising, poor wound healing, pigmentation and striae central obesity proximal myopathy frontal balding in women Osteoporosis
Why is osteoporosis a unique characteristic in cushing’s syndrome?
the person will be obese and usually obesity protects from osteoporosis
Describe investigations for cushing’s syndrome?
Most sensitive= overnight dexamethasone suppression test. Synthetic glucocorticoid should lower cortisol to less than 50nmol/L in normal individuals as this switches off negative feedback loop
24hr urinary free cortisol can be measured but can still get normal values with disease
Loss of diurnal variation in cortisol- need to take several measurements throughout the day
Treatment of Cushing’s syndrome?
1st line=surgery Often metyrapone (adrenal steroid synthesis inhibitor) is helpful in controlling symptoms and also helps prepare patient for surgery
Most sensitive test for cushing’s syndrome?
Overnight dexamethasone suppression test
What does panhypopituitarism refer to?
Deficiency of all anterior pituitary hormones
Panhypopituitarism is most commonly caused by…
pituitary tumours, surgery or radiotherapy
Causes of hypopituitarism?
MOST COMMON
pituitary tumours, surgery or radiotherapy
OTHER CAUSES
granulomatous disease, other local brain tumours or metastases, vascular diseases, trauma, infection and auto-immune diseases (Sheenan post pregnancy)
Symptoms of hypopituitarism?
Generally symptoms are same as symptoms of primary deficiency or peripheral endocrine gland
Presence of what suggests that multiple defects of anterior pituitary are unlikely?
Normal gonadal function (makes sense as controlled by multiple axis)
Investigations for hypopituitarism?
Each axis of the hypothalamic-pituitary system requires separate investigation
Treatment for hypopituitarism?
If tumour- surgery
treat underlying cause
Hormone replacement: thyroxine, hydrocortisone, ADH, sex steroids (HRT/oest/ prog pill for females and testosterone for males)
GH still given in adults as improves quality of life
Why is growth hormone still replaced in adults?
Improves quality of life- decreases abdo fat, increases muscle, cardiac function etc
Side effects if testosterone replacement and cautions?
Causes prostate enlargement and does not cause cancer but may make it grow. Also causes polycythaemia (increased RBC) which increases risk of stroke/ MI so must monitor FBC.
Causes of cranial diabetes insipidus?
familial causes idiopathic in 50% of cases Trauma tumour Sarcoidosis is a fairly common cause
Investigation for cranial diabetes insipidus?
water deprivation test- can they concentrate urine when dehydrated for 8 hrs
Treatment of cranial diabetes insipidus?
desmospray or desmopressin tablets
Pituitary mass and diabetes insipidus likely cause…
metastases not a primary tumour
2 causes of obesity and hypertension?
Part of metabolic syndrome (obesity hypertension hyperlipidaemia increased CV risk)
Cushings
Why do you usually get hypoglycaemia in in hypopituitary?
Lack of glucocorticoids which usually help prevent hypoglycaemia (cortisol raises blood sugar)
In hypopituitarism what should you replace first? Why? What is risk?
steroids then thyroxine
must give steroids first or you may precipitate an adrenal crisis
If you think someone has excess of a hormone you do a ____1_____
If you think someone is deficient in a hormone you do a ___2_____
1) suppression test
2) challenge test
