Endocrinology Flashcards
Hormones from posterior pituitary and target tissue
Vasopressin - renal tubules
Oxytocin - breast and uterus
Hormones from anterior pituitary and target tissue
LH/FSH - ovaries and testis Growth hormone - lots of tissues TSH - thyroid Prolactin - breasts and gonads ACTH - adrenals to make steroids.
What is the function of the adrenal cortex
Make mineralocorticoids e.g. aldosterone, glucocorticoids e.g. cortisol and androgens e.g. DHEA
Difference between Cushing’s syndrome and Cushing’s disease
Syndrome = any cause of chronic excessive glucocorticoids. Disease = cause of excessive glucocorticoids is due to a pituitary adenoma
Causes of Cushing’s syndrome
STEROIDS USE (low ACTH) Other low ACTH, loss of negative feedback loop and hence 'ACTH-indpendent' causes = Adrenal carcinoma, adrenal nodular hyperplasia.
ACTH-dependent/high ACTH levels = Cushing’s disease/Pituitary adenoma, small cell lung cancer paraneoplastic syndrome/ectopic ACTH production.
S+S of Cushing’s syndrome
Weight gain Central obesity and moon face Proximal muscle weakness Bruises Acne Irregular menses, erectile dysfunction Mental change e.g. depression, irritability
O/E: Facial plethora, buffalo hump, supraclavicular fat pads. Hirsutism Purple striae on abdo Osteoporosis or unexplained fractures High BP Glucose intolerance/high BM.
Investigating for Cushing’s syndrome
Bloods = HbA1c, plasma ACTH levels, pregnancy test in females.
Other Lab = ∆ overnight dexamethasone suppression test (Failure to suppress cortisol <50nmol/L = +ve for Cushing’s) or 3x24hr urinary free cortisol (high). In secondary care can do a 48hr suppression test or higher-dose.
Imaging = pituitary MRI.
Mx of Cushing’s syndrome
If Cushing’s disease = transsphenoidal pituitary adenomectomy.
Stop steroids.
Metyrapone for symptomatic relief for ectopic ACTH.
Name 4 skin changes in Cushing’s
Purple striae
Easy bruising
Hirsutism
Acne
Normal cortisol level fluctuation
Diurnal - highest in morning and lowest at midnight.
Adrenal insufficiency causes
Primary adrenal insufficiency = Addison’s disease. Autoimmune destruction of adrenal cortex leading to glucocorticoids and mineralocorticoid deficiency. Primary insufficiency also caused by TB (globally most common cause!), lymphoma, adrenal mets from kidneys, breast, lung.
Secondary adrenal insufficiency = long-term steroid therapy (on withdrawal of steroids only)
S+S of Addison’s/Adrenal insufficiency
In adrenal crisis. Chronic symptoms: so vague 🤕 Fatigue Weight loss, anorexia, premature satiety. Nausea, vomiting, abdo pain, salt cravings. Muscle cramps and arthralgia Headache Polyuria and polydipsia
O/E:
Hyperpigmentation at scars, pressure points, palmar creases, mucus membranes.
Muscle weakness
Females loose pubic hair
Differentials for adrenal insufficiency
Anorexia - will have a potassium but in Addison’s its raised.
Investigating adrenal insufficiency
Primary care = MORNING serum cortisol (refer if less than 500nonomol/L, admit ASAP if less than 100), U+E (low Na, high K), BM low.
Secondary care = adrenocorticotrophic hormone stimulation test (Synacthen) which involves injection of an ACTH synthetic analogue and measuring serum cortisol. serology for 21-hydroxylase autoantibody, plasma renin (high) and aldosterone (low).
Exclusion = HbA1c.
Antibody common in Addison’s disease
21-hydroxylase autoantibody.
Management of confirmed adrenal insufficiency
Glucocorticoid replacement = hydrocortisone, prednisolone, dexamethasone. Resemble physiological release so higher dose in morning and then smaller doses at lunch and evening.
Mineralocorticoid replacement = Fludrocortisone
Safety net advise for features of an adrenal crisis. Increase steroids on sick days.
Who get Addison’s
Females on steroids
2 drugs for Addison’s
Hydrocortisone and fludrocortisone.
S+S of Addisonian crisis
Abdo pain Tachycardia Hypotensive Low grade fever Oliguria Altered mental state/confused Hx of steroid use.
Precipitated by infection, trauma, surgery, missed replacement therapy.
Ix and Mx for Addisonian crisis
A to E resuscitation. Urgent Ix = serum cortisol, serum ACTH, U+E, BM, ECG IV Hydrocortisone IV fluid bolus Monitor and ween IV to oral steroids.
Adrenal cortex haemorrhage in a meningococcal septicaemia patient
Waterhouse-Friderichsen syndrome. Rx = Ceftriaxone + IV hydrocortisone.
Diabetes Mellitus Type 1 and Type 2 pathophysiology
T1 = Deficient insulin secretion due to destruction of beta-cells in pancreatic Islets of Langerhans, majority is autoimmune destruction. T2 = Insulin resistance/insensitivity as body is unable to respond to serum insulin and relative insulin deficiency as pancreas is unable to secrete enough insulin to compensate for resistance.
RFx for Type 2 DM
Obesity Inactivity FHx Asian, African or black ethnicity. Hx of gestational diabetes. PCOS Drugs = second generation antipsychotics, corticosteroids.
Micro and Macro - vascular complications of DM and other random complications.
Macro: CVD e.g. MI, stroke/TIA, peripheral arterial disease (intermittent claudication).
Micro: retinopathy, nephropathy (hyperfiltration), neuropathy (glove and stocking).
Other: depression, infections esp UTI, increased risk of dementia.