Endocrine and Metabolic disease Flashcards
Autoimmune thyroiditis / Hashimotos thyroiditis Antibodies Associations Mx
Transient hyperthyroid before eventual hypothyroid (most common cause)
10x more common in women
Firm NON-TENDER goitre
Anti-thyroid peroxidase (TPO) and anti-Tg antibodies
Associated with DM, Addisons and pernicious anaemia
Treated with thyroxine
Subacute (De Quervain’s) thyroiditis Remember raised ESR and painful goitre
Usually follows a viral infection and presents with hyperthyroid before settling as hypothyroid
Raised ESR and painful goitre
Globally reduced uptake on iodine-131 scan
Usually self limiting but steroids and aspirin can help
The most common cause of hypothyroidism in the developing world
Iodine deficiency
Drugs that can cause hypothyroidism
Radioiodine (for hyperthryoid treatment)
Lithium
Amiodarone (can also cause hyperthyroidism)
Postpartum thyroiditis
Hyperthyroid followed by potential permanent hypothyroidism
Non-tender goitre (only painful when infection)
Treat symptoms with beta blockers and perhaps thyroxine if hypothyroidism develops
Graves disease
Most common hyperthyroidism
Thyroid eye disease
Pretibial myxoedema: erythematous, oedematous lesions above the lateral malleoli
Thyroid acropachy: clubbing
Diffuse goitre (TMG is nodular)
TSH antibodies
Treated with Propylthiouracil/thiamazole
Toxic multinodular goitre
Differences from Graves
Older than graves, nodular goitre as opposed to diffuse, less marked symptoms than Graves.
Not always autoimmune antibodies
NO exopthalmos or pretibial myxoedema
Thyroid nodules
Hot usually pump out hormones whilst cold are non-functioning or cancerous
TFTs
- Thyrotoxicosis (Graves)
- Primary hypothyroidism (Hashimotos)
- Secondary hypothyroidism
- Sick euthyroid syndrome
- Subclinical hypothyroidism
- Poor compliance with thyroxine only take meds days before blood test)
TSH T4
- Low High
- High Low
- Low Low
- Low Low (systemic illness)
- High Normal (on the way to developing hypothyroidism - TSH are more sensitive and early marker!)
- High Normal (T4 is normal as patient has taken dosage but the hypothyroid high TSH still remains and lags’ behind)
Hypoparathyroid
Cause
Labs
Clinical
Post-surgery, autoimmune
Low PTH Low calcium
CATS go numb: Convulsions Arrhythmias - QT prolongation Tetany (Trousseau + Chovsteks) Spasms, seizures and stridor
Trousseau and Chovsteks sign
Seen in hypoparathyroidism
Trousseau: Latent tetany. Raise BP until brachial artery is occluded low calcium neuromuscular irritability will unduce spasm of muscles = flexion of wrist and MCP joints into claw
Chvostek: Twitch after tapping facial nerve
Central hypothyroid
Cause
Labs
Clinical
Like hypothyroid but with Pituitary adenoma
TSH low T4 low
MRI sellar/parasellar mass
Mass causes papilloedema and visual field defects (bitemporal hemanopia) Symptoms of
hypoPituitarism too, hypogonadism and secondary adrenal insuffieincy
Primary Hyperparathyroidism
Cause
Labs
Clinical
Parathyroid adenoma, hyperplasia or syndromic MEN1 MEN2 causing excessive PTH secretion
PTH High
Calcium High
Phosphate Low
ALP High
Often asymptomatic
Stones, bones, abdo groans, psych moans
Secondary Hyperparathyroidism
Cause
Labs
Clinical
Low calcium causing physiological increase in PTH.
Usually Vit D deficiency or CKD
PTH High Calcium Low (or normal)
Rickets, osteomalacia, renal osteodystrophy
Often has low calcium AND phosphate! unusual
Adrenal failure/Addisons (low cortisol and aldosterone)
Labs/Diagnosis
Clinical
Treatment
Differences
Postural hypotension, Na Low, K High, Aldoseterone Low, Glucose Low, Renin High (compensate for low Na hypovolemia), Androgens Low.
Acidosis (Low Na High K in Addisons and thus to try and remove K the body exchanges for H+ and lack of aldosterone driven loss of H+)
- Morning cortisol (highest point) - <83
- ACTH stimulation test - should double cortisol, but won’t
- Serum ACTH - high in Addisons disease, low in pituitary causes
Tired, anorexia, weight loss, hyperpigmentation (mucosal unlike haemochromoatosis), salt craving, nausea, vomiting, POSTURAL hypotension, arthralgia/myalgia
Dexamethasone + Fludrocortisone (mineralo)
High ACTH = hyperpigmentation thus addisons disease with low ACTH doesnt occur
K is only high in adrenal cause where aldosterone is lowered. Secondary has normal K levels
Cushings
Labs/diagnosis
Clinical
Treatment
High glucose, High Na and Low K due to high cortisol having activity on aldosterone receptor
Metabolic alkalosis due to aldosterone driven loss of H+ (and attempt to add K+ by removing H+)
- Late-night salivary cortisol (lowest point)
- > 50/24hr on urine cortisol test
- Serum cortisol level
- Dexamaethasone ‘low dose’ 1mg overnight supression test, next morning >50 cortisol = cushings. Merely to see if there is a problem as normally this should drop cortisol level!
- High dose 8mg dexamethasone test will suppress pituitary (as the axis is involved) but not ectopic source or adrenal or exogenous source
- ACTH serum level
Low ACTH = adrenal or iatrogenic source
High ACTH = Ectopic or pituitary adenoma (do MRI but also suppressed by high dose dexamethasone)
Inferior petrosal sinus sampling differentiates ectopic ACTH (lung/thyroid cancer) from pituitary ACTH.
Moon face, buffalo hump, stretch marks, amenorrhea, weight gain, height loss, female, HTN, gluocse intolerance, osteoporosis/fractures, acne, psych, low libido, bruising, weakness, hirtusim
Tumour: Surgery or mifepriston/ ketoconazole
If bilateral adrenal disease then remove + corticosteroid treament
Hyperaldosteronism/ Conn's syndrome Cause Labs/Diagnosis Clinical Treatment
Oedema?
Adrenal adenoma or hyperplasia
High Aldosterone, High Na, Low K, compensatory suppressed renin (via high aldosterone), hypokalemic alkalosis (attempt to add K by removing H+)
Increased aldosterone:renin ratio
Hypertension, polyuria, tetany, weakness
Spironolactone/surgery
If the patient has edema, it is not Conn’s
Testicular failure
Causes
Labs/Diagnosis
Clinical
Primary: Cryptorchidism (lack of testes), Klinefelter syndrome 47XXY (Mark Briggs)
Secondary: Absent gonadotrophin drive - GnRH or LH/FSH deficiency = Kallmann + anosmia
Primary: Low testosterone high FSH/LH
Secondary: Low Testosterone, Low FSH/LH
Anorchia, puberty delay/failure, infertility, small balls, low body hair, gynaecomastia, loss of muscle, feminine
Ovarian failure
Primary: Gonadal dysgenesis, premature menopause
Low estrogen, high FSH/LH
Secondary: FSH/LH deficiency > low Estrogen ie PCOS
PCOS clinical features
Irregular menses, unwanted body hair, subfertility, weight gain, CVD - insulin resistance and dyslipidemia
MEN syndromes
MEN1: 3Ps (MEN1 tumour suppressor mutation)
Parathyroid
Pancreas
Pituitary
MEN2a: 2P 1M (RET oncogene mutation)
Parathyroid (calcium)
Pheochromocytoma (catecholamines)
Medullary thyroid cancer (calcitonin)
MEN2b: 1P 2M
Pheochromocytoma
Medullary thyroid cancer
Marfanoid habitus/mucosal neuroma
Aldosterone action on Na K and H
Aldosterone reabsorbs Na and secretes K and H
Acidosis causes ? as it tries to reduce H for K
Alkalosis causes ? as it tries to increase H for K
Acidosis causes hyperkalemia
Alkalosis causes hypokalemia
Relationship between acidosis and hypercalcemia
Acidosis due to low aldosterone will cause hyperK and HyperCalc as less Ca can bind to albumin as H is there to bind to albumin instead
Hyponatremia
4 causes
Pseudohyponatremia: Low but actually just other osmolites filling the plasma, such as hyperglycemia, hypertriglyceridemia
Sodium depleton: Renal - diuretics, salt wasting, nephropathy, hypoadrenalism/addisons Extrarenal - GI loss
Excess water intake (most common): Dipsogenic DI (drink too much), IV therapy following surgery, post-marathon as deemed to be dehydrated but actually drank too much!
Reduced renal free water clearance: Hypovolemia (renal failure, hypoalbuminemia, sepsis), cardiac failure, nephrotic syndrome, SIADH
SIADH Definition Pathophysiology Diagnosis Causes
Excessive ADH which results in more water absorbed from kidney thus dilutes blood causing hyponatremia BUT the urine is sucked of all its water so urine osmolality of sodium is HIGH >20mmol/L (unwanted water retention via ADH)
Exclude - hypotension, oedema, adrenal failure, diuretics/ACEi, non-osmotic ADH release
Causes: CNS - inflamm, tumour, infection
Tumour associated chest disease - SCLC
Malignancy
Drugs - TCAs!
Adaptation to hyponatremia
And risk of correcting too quickly
- Water follows gradient into higher solute brain cells
- Cerebral oedema
- Rapid adaptation - loss of inorganic osmolytes (Na,K,Cl) from neurons > water follows
- Slow adaptation - loss of organic osmolytes
Osmotic demyelination syndrome - Quadriplegia, opthalmolegia, psuedo-bulbar palsy, coma
Management algorithm for hyponatremia
- Exclude other osmolytes causing the hyponatremia such as hyperglycemia
- Severe symptoms such as coma/seizure? Give small amount of hypertonic saline to minimize symptoms as opposed to achieving perfect Na value
- If they’ve had low sodium for years then correcting has a higher risk of demyelination and so need to correct slowly, but if there was a rapid drop in sodium then you can correct in quickly too
- If they don’t have sever symptoms then check urine osmolality and diagnose… = cause specific treatment
Diagnostic algorithm for hyponatremia
- Exclude non-hypotonic hyponatremia such as high glucose levels
- Check urine osmolality, if <100/ low concentration of urine – are they given IV fluids? Drinking too much water? Too much beer?
- If urine osmolality is high, so your urine is high concentration, what is urine sodium concentration?
a. <30 low sodium = body is holding onto sodium due to volume depletion, vomiting, diarrhea, nephrotic syndrome
b. >30 high sodium = could be on diuretics or ACEi? If so then this masks cause and thus could be anything. If not then SIADH
Hypernatremia
Pathophysiology
Types
Treat
Rare, seen in elderly during germinal illness
Water loss > water intake OR rarely too much salt (infants)
Hypovolemic: Dehydrated from decreased water intake or excesive loss via osmotic diuretics/sweating
Euvolemic: Diabetes insipidus causing inadequate ADH from pituitary gland or impaired response in kidney to ADH thus excessive excretion of water
Hypervolemic: Due to intake of high solute fluids such as seawater
Saline
