Download Thyroid Problems - Improving Care In ED

Thyroid Problems
Pathophysiology
Goitre
T4: 80%; 1/3 converted to T3; 45% to RT3; >99% protein bound
T3: 20%; mostly derived from T4; >99% protein bound; more biologically active than T4 as more free
RT3, calcitonin
TSH: reflects thyroid function better than thyroxine; normal = 0.3-5
Effects: metabolism of cholesterol/carbohydrate/protein/lipids;  GI motility;  glucose absorption; 
protein catabolism;  sensitivity to norepinephrine and epinephrine,  beta-receptors; required for
development, lactation
Idiopathic (most); puberty, pregnancy; thyroiditis (eg. Hashimoto’s, de Quervains), iodine deficiency /
excess, congenital
Solitary Nodule
Multi-nodular goitre with dominant nodule (most common), adenoma, cyst, cancer (1Y or 2Y from renal),
lymphoma (rare)
Hyperthyroidism
Thyrotoxicosis:  hormone from any cause
Aetiology: Graves disease: 80-90%; F>M; affects 1% women; peak 30-40yrs; due to production of LATS
hormone (an IgG auto-antibody causing type II hypersensitivity reaction; 50% have eye signs)
Toxic multinodular goitre
Thyroiditis (eg. Post-partum; Hashimoto’s, de Quervains)
Drug induced (eg. Amiodarone, iodine, lithium, alpha-interferon, thyroid hormones)
Other: ectopic thyroid tissue, pituitary adenoma
Symptoms: nervous,  sweating, heat intolerance, palpitations, tremor, weakness, weight loss,
abdominal pain, diarrhoea, amenorrhoea, libido, emotional lability, psychiatric issues
Examination: enlarged thyroid, bruit, eyes (exopthalmus, chemosis, lid retraction, lid lag, corneal
ulceration, optic atrophy,  power IO then convergance), tremor, hyperreflexia, clonus, myopathy,
thyrotoxic periodic paralysis, hot hands,  HR (40%), AF (10-35%), CCF, HTN, wide pulse pressure (water
hammer), SOB, pretibial myxoedema, onycholysis, alopecia, palmar erythema
Investigation: TSH <0.1;  T3/4; thyroid autoantibodies in Graves; normochromic anaemia,  WBC, mild
 Ca,  albumin,  AST/ALP
Management: carbimazole 10-45mg PO BD/TDS
propylthiouracil 200-600mg PO BD/TDS:  iodination in thyroid gland   synthesis and
release of new hormone, but no effect on stored hormone;  peripheral T4  T3
conversion
Thyroid Storm
Occurs in 1%; clinical diagnosis as lab studies can’t tell hyperthyroidism from storm; ?due to adrenergic
sensitivity, altered peripheral T3 response,  free hormone; mortality untreated 90%, treated 10-15%;
death usually due to cardiovascular collapse; may last 8-10/7, but average 3/7
Aetiology: undiagnosed Graves disease; withdrawal from anti-thyroid drugs; infection; MI; DKA; surgery;
iodine / contrast; thyroxine toxicity
Examination: diagnostic criteria: sudden onset; fever (>37.8)
+  HR out of proportion (120-200)
+ CNS disturbance (in 90%; altered LOC, seizures)
Also: abdominal pain, nausea, vomiting, diarrhoea; CCF (high output), wide pulse pressure and HTN, \
profuse sweating, dehydration
Investigations:  T3,4;  TSH; others don’t show anything specific
Management: ABC (O2 as consumption ; IV fluids with dextrose; DC cardioversion for arrhythmias as
likely resistant to others); treat cause
Propylthiouracil 900-1200mg PO loading  300mg/day; onset 1hr but takes weeks for full effect
Lugol’s iodide 5 drops TDS; start >1hr after prop;  new hormone production
Propanolol 0.5-1mg/min IV to max 10mg  repeat 3-4hrly PRN  20-120mg Q4-6hrly PO; blocks
cardiac and peripheral effects; slows conversion of T43; can be used in CCF
Esmolol 250 - 500mcg/kg bolus  50-100mcg/kg/min inf if concerned Re: CCF / COPD as β-1 selective
Reserpine 2.5-5mg IM if beta-blockers CI’ed
Hydrocortisone 100mg / dexamethasone 2mg QID; decr peri conversion of T43,  metabolic
demands,  hormone release
Cholestyramine:  enterohepatic circulation of T3,4
Supportive: fluid status, electrolytes, glucose, decr fever (not aspirin)
Others: dialysis, plasmapheresis, charcoal haemoperfusion
Hypothyroidism
Aetiology: autoimmune (Hashimoto’s – hypothyroid with bouts of hyperthyroidism)
Iodine 131, post surgery, external irradiation
Drugs (amiodarone, lithium)
Infiltrative (eg. Lymphoma, sarcoid, TB, amyloidosis)
Other: Idiopathic, iodine deficiency (most common cause worldwide), post-partum thyroiditis
2Y: pituitary / hypothalamic lesions
Examination: hypothermia, DUB, constipation; cool dry hands; small volume pulse;  HR; +ive Tinel’s
sign; proximal myopathy; myalgia; yellow thick skin; large tongue; alopecia; facial swelling; xanthelasma;
coarse brittle hair, periorbital oedema; pericardial / pleural effusion; slow relaxation of ankle jerks;
peripheral neuropathy; carpal tunnel; deafness; mental slowing; depression
Investigations: TSH >7 (1Y) – TSH most sensitive;  TSH if 2Y; anaemia (folate, B12, Fe deficiency,
haemolysis);  T4 (but not T3; FT4 may be normal early); thyroid auto-antibody for Hashimoto’s
Management:  dose by 30% in pregnancy; use half dose in elderly; Thyroxine 75-150mcg/day
Myxoedema
Coma
Symptoms:  LOC,  temperature (but no shivering), seizures,  RR,  BP (SBP <100 in 50%),  HR,
hypoglycaemia, hyponatraemia, paralytic ileus, megacolon, urinary retention, ankle oedema, CCF,
hoarseness, glottic oedema, low voltage ECG (long QTc, flat/inverted T waves); precipitated by infection,
CVA, MI, medication changes; mortality 50%
Management: ABC; treat cause
T3 25-50mcg IV bolus  10-20mcg TID; rapid onset; side effects = arrhythmia
T4 300-500mcg IV bolus  50mcg IV per day; smoother improvement; less side effects;
slower onset
Hydrocortisone 100mg QID; as impaired glucocorticoid response to stress
Supportive care: water restriction if hypoNa; rewarming