Hyperthyroidism: Systemic Effects Beyond the Thyroid

Excess thyroid hormone affects virtually every organ system.

Cardiovascular

• Tachycardia, palpitations, atrial fibrillation (10–15%)
• High-output heart failure, widened pulse pressure
• Increased cardiac output, decreased systemic vascular resistance

Neurological / Psychiatric

• Anxiety, nervousness, irritability, emotional lability
• Insomnia, fatigue (paradoxical)
• Fine tremor, hyperreflexia
• Rare: psychosis, seizures

Gastrointestinal

• Increased appetite, weight loss (malabsorption, hypermotility)
• Diarrhea, steatorrhea
• Nausea, vomiting

Reproductive

• Oligomenorrhea, amenorrhea, infertility
• Increased SHBG → altered estrogen/testosterone ratios

Dermatologic

• Warm, moist skin; palmar erythema; onycholysis (Plummer's nails)
• Fine hair, alopecia
• Pretibial myxedema (Graves'-specific)

Ocular (Graves' Orbitopathy)

• Lid retraction, exophthalmos, stare
• Diplopia, blurred vision, corneal exposure
• Activity graded by CAS (Clinical Activity Score)

Skeletal

• Accelerated bone turnover → osteoporosis, fracture risk
• Hypercalciuria, nephrolithiasis

Comprehensive management addresses all systems — not just thyroid levels.