Hypothyroidism
Most common: Hashimoto thyroiditis. Symptoms: fatigue, weight gain, cold intolerance, constipation, dry skin, bradycardia. Diagnosis: elevated TSH, low free T4. Treatment: levothyroxine on empty stomach, 30-60 min before breakfast.
Hyperthyroidism
Most common: Graves disease. Symptoms: weight loss, heat intolerance, palpitations, tremor, anxiety, diarrhea, exophthalmos. Diagnosis: suppressed TSH, elevated free T4/T3. Treatment: antithyroid drugs, radioactive iodine, thyroidectomy.
Emergencies
Thyroid storm: hyperthermia >104F, tachycardia, altered mental status — treat with PTU, iodine, beta-blocker, hydrocortisone. Myxedema coma: hypothermia, hypoventilation, bradycardia, hyponatremia — treat with IV levothyroxine, hydrocortisone.
Important Notes
- Levothyroxine on empty stomach — calcium, iron, food significantly reduce absorption.
- Thyroid storm is medical emergency — mortality 20-30% without prompt treatment.
Clinical Tips
- PTU preferred in pregnancy first trimester (methimazole is teratogenic).
- Switch from PTU to methimazole after first trimester (lower hepatotoxicity).
Summary
Thyroid disorders require identifying type, appropriate replacement or suppression therapy, and recognition of emergencies.
