Presentation Symptoms/Physical exam Hypothyroidism Hyperthyroidism Cold intolerance (↓ heat production) Heat intolerance (↑ heat production) Weight gain, ↓ appetite Weight loss, ↑ appetite Hypoactivity, lethargy, fatigue, weakness Hyperactivity Constipation Diarrhea ↓ reflexes ↑ reflexes Bradycardia Tachycardia, palpitations, arrhythmias Dry, cool skin; coarse, brittle hair Warm, moist skin; fine hair Diastolic hypertension (Na/H20 retention) Systolic hypertension Myxedema (facial/periorbital) Osteoporosis Apathetic thyrotoxicosis Evaluation Labs Hypothyroidism Hyperthyroidism ↑ TSH (Best first test) ↓ TSH (Best first test) ↓ total T4 ↑ total T4 ↓ free T4 ↑ free T4 Hypercholesterolemia (↓ LDL receptor synthesis) Hypocholesterolemia (↑ LDL receptor synthesis) Treatment Hypothyroidism Hyperthyroidism Levothyroxine Thionamides, Ablative 131I therapy