Day 5 - Thyroid Disorders
Hyperthyroidism
Signs & symptoms:
Heat intolerance
Weight loss
Anxiety
Tachycardia
Hypertension
Pretibial myxedema, ophthalmopathy (Graves)
Thyroid storm:
Life threatening condition as a result of severe untreated hyperthyroidism
Hallmark features of hyperpyrexia, cardiovascular dysfunction and altered mentation
Burch & Wartofsky score used to diagnose & risk stratify
Investigations:
TSH (low)
Free T4 (high)
Free T3 (high)
TRAb
Radioactive Iodine Uptake & Thyroid scan
Treatment:
Symptom relief:
Volume repletion
Non-selective β-blockers ie. propranolol, metoprolol; calcium channel blockers if contraindicated
Anti-thyroid medications:
Propylthiouracil (PTU) 1000mg x1 then 300mg q6h
Methimazole 30mg po q6h
Address underlying condition:
Radioactive iodine
Thyroidectomy
Thyroid storm:
β-blocker
PTU
Glucocorticoids for potential concomitant adrenal insufficiency
Hypothyroidism
Signs & symptoms:
Cold intolerance
Weight gain
Fatigue
Hair loss
Bradycardia
Diastolic hypertension
Myxedema coma:
Life threatening condition as a result of severe untreated hypothyroidism
Hallmark features of hypothermia, bradycardia, hypotension, hypoxemia, hypoventilation, hypoglycemia, hyponatremia, coma and shock
Generally markedly elevated TSH
Investigations:
TSH
Elevated in primary hypothyroidism
Low or inappropriately normal in tertiary hypothyroidism
Free T4 (low)
Free T3 (low/normal)
Treatment:
Thyroid replacement with oral levothyroxine
Starting dose generally 50mcg po daily, although consider starting at a lower dose in elderly and those at high risk for delirium and adverse effects
Repeat TSH 6 weeks after initiation
Dose is targeted to normalize TSH and improve symptoms, NOT guided by T4 levels
Myxedema coma:
Treatment with IV thyroid hormone
Levothyroxine 200 - 400mgmcg IV, then 50 - 100mcg daily
Triiodothyronine 5 - 20mcg IV, then 2.5 - 10mcg q8h
Adjunctive corticosteroids for potential concomitant adrenal insufficiency (continue until this has been ruled out)
Hydrocortisone 100mg IV q8h