Clinical Features of Hyperthyroidism in the Elderly
Hyperthyroidism in the elderly often presents atypically, lacking the classic triad of T3/T4 hypersecretion, goiter, and exophthalmos. Instead, it may manifest as isolated cardiovascular, gastrointestinal, or neurological symptoms, leading to frequent misdiagnosis.
Key Clinical Manifestations of Thyrotoxic Heart Disease
1. High Metabolic State
- Weight loss (80% of elderly patients, often the first symptom).
- Heat intolerance, sweating, and warm/moist skin (palms, soles, chest).
- Muscle wasting and fatigue due to protein catabolism.
2. Cardiovascular Symptoms
(1) Arrhythmias
- Sinus tachycardia (90–120 bpm, persistent at night; resistant to rest/sedatives).
- Atrial fibrillation (AF) (25% in patients >60 years; new-onset AF in the elderly warrants thyroid screening).
- Bradyarrhythmias (rare): Sinoatrial block, AV block, or sinus arrest (linked to autoimmune conduction system damage).
(2) Cardiomegaly and Heart Failure
- Early-stage: Pulmonary artery prominence, left ventricular hypertrophy (“thyrotoxic hypertrophic cardiomyopathy”).
- Advanced: Biventricular enlargement, right-sided heart failure (10–25% incidence). AF quadruples heart failure risk.
(3) Ischemic Heart Disease
- Angina/Myocardial infarction (10–20% of cases; coronary arteries typically normal on angiography).
- Mechanisms:
- ↑ Myocardial oxygen demand + ↓ coronary perfusion (tachycardia-induced diastolic shortening).
- Coronary vasospasm (autonomic dysfunction).
(4) Other Mechanisms
- Microvascular thrombosis.
- Lactic acidosis from hypermetabolism.
3. Atypical Systemic Symptoms
(1) Gastrointestinal
- Anorexia (1/3 of elderly patients; contrasts with classic hyperphagia).
- Nausea, vomiting, constipation.
(2) Neuropsychiatric
- Apathetic hyperthyroidism (lethargy, depression, cognitive decline > agitation).
(3) Hematologic
- Neutropenia (<3.0×10⁹/L), lymphocytosis, thrombocytopenia.
(4) Musculoskeletal
- Proximal myopathy (difficulty climbing stairs, combing hair).
- Osteoporosis (↑ fracture risk, especially in postmenopausal women).
(5) Thyroid Enlargement
- Goiter is often subtle or absent in the elderly.
Physical Examination Findings
- Classic signs:
- Bounding precordium, loud S1, accentuated P2, S3 gallop.
- AF: Irregular rhythm, pulse deficit.
- Atypical signs: Premature beats, tachycardia.
Diagnostic Criteria for Thyrotoxic Heart Disease
Diagnosis requires confirmed hyperthyroidism (↑ T4/FT4, ↑ T3/FT3, ↓ TSH) plus one or more cardiac abnormalities that resolve with thyroid normalization:
- Significant arrhythmia: AF, frequent atrial ectopy, bundle branch block.
- Cardiomegaly (unilateral or bilateral).
- Angina or myocardial infarction post-hyperthyroidism onset.
Key Laboratory and Imaging
- Thyroid function tests: Gold standard for hyperthyroidism.
- Echocardiography: Assess ventricular hypertrophy, ejection fraction.
- Coronary angiography: Rule out atherosclerotic disease if ischemia present.
Management Principles
- Antithyroid therapy (methimazole, propylthiouracil) to normalize T3/T4.
- Rate control: Beta-blockers for tachycardia/AF (avoid in bradyarrhythmias).
- Heart failure: Diuretics, ACE inhibitors (caution in right-sided failure).
- Arrhythmia reversal: AF often resolves with euthyroidism; anticoagulate if persistent.
- Avoid permanent pacemakers unless irreversible conduction defects.
Prognosis: Cardiac abnormalities typically reverse with timely thyroid control.
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