Snapshot A 32-year-old woman presents to the clinic complaining of fatigue and weight gain for the past 2 months. She endorses cold intolerance, constipation, and dry skin but denies fever, diarrhea, swelling, chest pain, or shortness of breath. A physical examination demonstrates a lethargic, stocky patient with brittle hair. Her past medical history is significant for asthma that is well controlled with her rescue inhaler. Her laboratory studies demonstrate elevated levels of thyroid stimulating hormone. (Hashimoto thyroiditis) Hypothyroidism Clinical definition login to view 1 more bullet Epidemiology Demographics login to view 2 more bullets ETIOLOGY Pathogenesis login to view 27 more bullets Hyperthyroidism Clinical definition login to view 1 more bullet Epidemiology Demographics login to view 2 more bullets ETIOLOGY Pathogenesis login to view 18 more bullets Presentation Hypothyroidism Hyperthyroidism Cold intolerance (↓ heat production) Heat intolerance (↑ heat production) Weight gain and ↓ appetite Weight loss and ↑ appetite Hypoactivity, lethargy, fatigue, and weakness Hyperactivity Constipation Diarrhea ↓ Reflexes ↑ Reflexes Bradycardia Tachycardia, palpitations, arrhythmias Dry, cool skin and coarse, brittle hair Warm, moist skin and fine hair Diastolic hypertension Systolic hypertension Myxedema (facial/periorbital) Osteoporosis and hypercalcemia "Myxedema madness": syndrome characterized by psychosis, confusion, and disorientation Apathetic thyrotoxicosis Studies Diagnostic testing login to view 2 more bullets 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 Dose should be increased during pregnancy due to increased TBG Thionamides (e.g.,methimazole) Ablative131I therapy Propranolol (rate/symptom control) Complications Myxedema coma (hypothyroidism) Thyroid storm (hyperthyroidism)