Endocrinology Flashcards
Hormones in calcium homeostasis
PTH released by parathyroid in response to low CA, aids with absorption and releases Ca from bone
D3 vital for the absorption of Ca
Calcitonin released by thyroid in response to high Ca
Causes of hypercalcaemia
Excessive PTH secretion Malignancy (PTH independent) Excessive action of D3 Excessing dietary intake Drugs - thiazide diuretics, lithium, vit D, vit A
Symptoms of hypercalcaemia
General - fatigue, dehydration, confusion, depression, irritability
Renal - renal stones, polyuria
MSK - bone pain, calcifications in hyaline cartilage
GI - Abdo pain, constipation, nausea and vomiting
“Bones, Stones, Groans, Moans”
Causes of hypocalcaemia
Raised phosphate (CKD, phosphate based treatment)
Hypoparathyroidism
Low vitamin D (e.g. short gut, cirrhosis, CKD, resistance)
Acute pancreatitis
Acute rhabdomyolysis
Calcium chelators
Tumour lysis post chemo
Symptoms of hypocalcaemia
CNS - irritation, confusion, seizures, cognitive change
PNS - Spasms and cramping (tetany), periorbital and peripheral parathesia
Cardio - bradycardia, arrhythmia, hypotension, long QT
Investigating Hypocalcaemia
Calcium levels adjusted for albumin + albumin levels
PTH levels - best in morning, low in hypoparathyroidism, raised in via D deficiency, renal disease, malignancy with bony involvement
Vitamin D levels
ALP - raised in bony mets independent of other liver markers
Phosphate - raised phosphate in context of no renal failure or tissue points to hypoparathyroidism or pseudohypoparathyroidism
Magnesium - hypomagnesaemia and severe hypermagnesaemia causes hypocalcaemia
Renal function to rule in/out renal failure
Creatinine Kinase to rule in/out rhabdomyolysis
Amylase/Lipase to rule out pancreatitis
ECG to check for arrhythmia
Investigating Hypercalcaemia
PTH levels - hyperparathyroidism accounts for 90% of cases, very low PTH could point to malignancy
Vitamin D for vit D intoxication
Renal function
CXR for sarcoidosis if pulmonary symptoms
Typical labs in Adrenal Crisis
Hyponatraemia
Hyperkalaemia (primary)
Low aldosterone and high renin (primary)
Raised creatinine due to hypovolaemia
May have Hypoglycaemia
May have raised lymphocytes and eosinophils
Symptoms of Adrenal Crisis
Hypotension, postal hypotension, dizziness
Abdominal pain, nausea, vomiting, weight loss
Confusion, lethargy, delirium, coma
Cramps in back and legs
Hypovolaemic shock
Tumour locations in Multiple Endocrine Neoplasms Type 1 (MEN I)
Parathyroid glands
Endocrine GI tract
Anterior pituitary
Pituitary Adenoma Size Classifications
Microadenoma < 10mm
Macroadenoma > 10mm
Pituitary Adenoma Histology Classifications
Chromophobe - most common, secrete prolactin or are non functioning
Acidophil - secrete GH or prolactin
Basophil - secrete ACTH and rarely cause pressure
Symptoms due to compression of pituitary adenoma
Headache due to pressure
Bitemporal hemianopia due to option chiasm pressure
Diplopia from pressure on CN III, IV and VI
Haemorrhage or infarct of pituitary (apoplexy) leading to severe headache, visual disturbance and lack of essential hormones causing adrenal crisis
Hypogonadism - soft and small testes, ED, gynaecomastia, amenorrhoea, infertility, low libido, breast atrophy, hot flushes
Hypothyroidism - weight gain, fatigue, low mood
Adrenal insufficiency - nausea, vomiting, anorexia, weakness, adrenal crisis
Symptoms due to hormonal changes of pituitary adenoma
Hyperprolactinaemia leading to galactorrhoea, amenorrhoea and hypogonadism
Excessive growth hormone leading to acromegaly
Excess ACTH leading to Cushing’s
Hormones secreted by outer adrenal cortex
Steroid Hormones - Aldosterone, Cortisol, Sex Hormones
Hormones secreted by inner adrenal medulla
Catecholamines - adrenaline and noradrenaline
Symptoms of Cushing’s (raised cortisol)
Truncal obesity Moon face Buffalo hump Thinning hair Bruising and striae Hypertension Osteoporosis and fractures
Lab findings in Cushing’s
Raised cortisol - random or evening salivary
Positive dexamethasone tests
May be hyperglycaemic
Causes of Cushing’s
ACTH secreting pituitary adenomas
ACTH secreting tumour elsewhere such as lungs
Adrenal hyperplasia/adenoma leading to excess cortisol
Adrenal carcinoma
Iatrogenic from prolonged use of steroids
Addison’s causes a reduction in these hormones
Cortisol
Aldosterone
Symptoms of Addison’s
Fatigue Anorexia and weight loss Nausea, vomiting and diarrhoea Hyperpigmentation Depression and irritability Hypotension Arthralgia and myalgia
Lab findings in Addison’s
Low morning cortisol (<100 nanomol/L highly likely to be adrenal crisis)
Hyponatraemia (not always)
Hyperkalaemia (not always)
Hypoglycaemic (not always)
ACTH will be high in Addisons but low in secondary insufficiency
Synacthen test (ACTH) will not increase cortisol
High renin and low aldosterone
Autoantibodies positive in 80% of cases and tend to be IgG class
Causes of Addison’s
Presence of autoantibodies against adrenal gland
Congenital adrenal hyperplasia
Infections such as TB, HIV and CMV
Adrenal mets
Haemochromotosis
Amyloidosis
Iatrogenic causes such as adrenalectomy, adrenal haemorrhage from anticoagulation
Treatment for Addison’s and Adrenal Crisis
Glucocorticoid replacement - usually hydrocortisone
Mineralcorticoid replacement - usually fludrocortisone
ADRENAL CRISIS
High dose intramuscular hydrocortisone ASAP
IV fluids to stabilise and prevent renal failure