Endocrine Flashcards
Thyroid Symptoms
Thyrotoxicosis = weight loss, restless, heat intolerance, palp, arrhythmias, sweating, diarrhoea, oligomenorrhea, anxiety, tremor
Hypo = weight gain, tired, cold intolerance, dry skin, non-pitting oedema, dry coarse hair, lose lateral eyebrows, constipation, v deep reflexes, carpal tunnel, menorrhagia
Hypothyroid: Causes
Hashimoto’s Thyroiditis
Most common, AI destruction of thyroid, 10F:M
Link - coeliac, T1DM, Addison’s, pernicious anaemia
= firm non-tender goitre, MALT lymphoma
Inv - anti TPO, anti thyroglobulin
Iodine Def
Most common cause in developing world
Subacute Thyroiditis (De Quervain’s)
Hypothyroid post-viral infection
= painful goitre, hyper/ eu/ hypothyroid, self-limiting
Inv - ^ESR, global reduction of iodine uptake
Riedel’s Thyroiditis
Parenchyma replaced by dense fibrous tissue
= hard fixed painless goitre, middle-age F, retroperitoneal fibrosis
Others - post-radioiodine, post-partum, lithium, carbimazole, amiodarone, 2nd to Down’s, Turner’s, coeliac
Hyperthyroid: Causes
Graves Disease
Most common, TSH Ab mimic TSH, 40yr F
= exophthalmos, eye pain, pretibial myxedema, thyroid acropachy (digital clubbing, periosteal bone formation and soft tissue swelling)
Inv - TSH receptor stim Ab, anti-TPO, scintigraphy (diffuse homogenous and ^uptake)
-> propranolol for symptoms, may start carbimazole while waiting for referral
Toxic Multinodular Goitre
Autonomously functioning nodules secrete hormones
Inv - scint (patchy uptake)
-> radioiodine therapy
Amiodarone (stop)
Subclinical Thyroid
Hyper: low TSH, normal T3/4, observe/ try antithyroid for 6m
Hypo: high TSH, normal T3/4, treatment based on TSH level
> 10 (2x 3mths apart) - consider levothyroxine
5.5-10 - consider if <65yrs + symptoms, if no symptoms repeat TFTs in 6 months
Thyroid Function Tests Interpretation
. TSH Free T4
Primary Hyper - Low High
Secondary Hyper - High High
Sick euthyroid - Low Low
Subclinical Hyper - Low Normal
Subclinical Hypo - High Normal
Thyroxine incompliance - High Normal
Steroids - Low Normal
Sick euthyroid: very ill, back to normal when they recover
Thyroid Storm and Myxoedema coma
Storm
Rare, life-threatening comp of (established) thyrotoxicosis
Causes - infection, surgery, trauma, acute iodine load
= fever, tachy, ^BP, n+v, confusion, HF, jaundice
-> IV propranolol, anti thyroid drugs, maybe Dex (blocks conversion of T4-T3)
Myxedema Coma
Emergency, severe hypothyroid
= confused, hypothermia, coma
-> IV thyroid replace, IV fluids, IV steroids (until excl. adrenal insufficiency)
Thyroid Cancers
Rarely secrete hormones (euthyroid)
Types
Papillary: 70%, excellent prognosis, ^young F, spread to cervical nodes
Follicular: 20%, solitary nodule, vascular invasion
Medullary: cancer of parafollicular (C) cells, secrete calcitonin, MEN-2
Anaplastic: poor response to treatment, pressure symptoms, local invasion, elderly F
Lymphoma: link to Hashimoto’s
Inv - refer unexplained neck lump, US, biopsy
-> total thyroidectomy, radioiodine kills residual cells, yearly thyroglobulin for recurrence
SIADH
Hyponatremia 2nd to excessive water retention (dilutional), inappropriate release of ADH
Causes - small cell lung cancer, stroke, SAH, subdural, meningitis, TB, sulfonylureas, SSRIs, TCAs, vincristine, carbamazepine, cyclophosphamide
Inv - low plasma osmolality, high urine osmolality (^Na)
-> fluid restriction, ADH antagonists, slow correction of Na (central pontine myelinolysis)
Cushing’s Syndrome
Group of symptoms 2nd to excess cortisol in the body
ACTH-dependent
- Cushing’s disease (80%, pit adenoma secretes ACTH causing adrenal hyperplasia)
- ectopic ACTH (small cell lung cancer)
ACTH-independent
- steroids
- adrenal adenoma (Conn), adrenal carcinoma (rare)
- Carney complex (cardiac myxoma)
Inv - ABG (v K alkalosis), IGT, Dexamethasone Suppression
Overnight: morning cortisol spike not suppressed in Cushing’s
High-dose: cortisol and ACTH suppressed in Disease, only ACTH suppressed in Adrenal Adenoma, neither in Ectopic
Pseudocushings
Causes - alcohol excess or severe depression
Inv - false positive on dex suppression, insulin stress test to differentiate (GH and cortisol should rise after IV insulin)
Water Deprivation Test
For patients with polydipsia
Stop drinking, empty bladder -> hourly urine and plasma osmolality
Starting plasma, final urine, post desmopressin
Psychogenic - Low, >400, >400
Cranial DI - high, <300, >600
Nephrogenic - high, <300, <300
Hyponatremia
Hypovolemic
Causes - renal failure, thiazide/ loop diuretics, Addison’s
Euvolemic
causes - SIADH, hypothyroidism
Hypervolemic
Causes - HF, liver cirrhosis, nephrotic syndrome, PP
Also, burns, d+v, sweating
= headache, lethargy, n+v, dizzy, confused, muscle cramps, seizure, coma, resp arrest
Comp - cerebral oedema, brain herniation
Hyponatremia: Management
Mild <135, Moderate <130, Severe <120
-> Chronic >48hrs
Hypo - normal saline
Euvolemic - fluid restrict
Hyper - fluid restrict
-> Acute with symptoms
Hypertonic saline (3% NaCl) in HDU
Comp - osmotic demyelination syndrome (CPM, raise by 4-6 in 24hrs only)
Primary Hyperaldosteronism
Causes - bilateral idiopathic adrenal hyperplasia, Conn’s syndrome (adrenal adenoma)
= HTN + low K (muscle weakness), met alkalosis
Inv - high aldosterone: low renin, high res CT abdo and adrenal vein sampling (? uni/bilateral)
-> surgery for adenoma, spironolactone for hyperplasia
Congenital Adrenal Hyperplasia
AR, excessive androgens production 2nd to deficiency of 21-hydroxylase (11-beta/ 17)
= virilize female infant, early puberty in boys
DKA
Uncontrolled lipolysis, excess free fatty acids converted to ketones
= abdo pain, polyuria, polydipsia, deep hyperventilation (Kussmaul), pear drop breath
Inv - glucose > 11, pH 7.3, bicarb <15, ketones >3
-> Isotonic saline, + insulin infusion at (0.1u/kg/hour), + 10% dextrose infusion when glucose <14 (125ml/hr), may add K
Continue long acting insulin but stop short acting
DKA resolution = pH >7.3, ketones <0.6, bicarb >15
Endocrine review if not by 24hrs
Watch out for cerebral oedema post-resus (^young)
Metabolic Acidosis
Classified based on the anion gap (positive - negative ions)
Normal (10-18)
= GI bicarb loss (diarrhea, fistula), Addison’s, RTA, acetazolamide
Raised
= high lactate (shock, sepsis, hypoxia, metformin), ketones (DKA, alcoholic KA - glucose is normal), urate (renal failure), salicylate/ methanol poisoning
Primary Hyperparathyroism
Causes - 85% solitary adenoma, hyperplasia, multiple adenoma, carcinoma
Link - MEN1/2
= 80% asymp, otherwise high calcium (bones, stones, abdo groans and psychic moans)
Inv - norm or ^PTH, ^Ca, v phosphate, skull XR (pepper pot)
-> parathyroidectomy, conservative using calcium mimetic (cinacalcet)