How to manage tremors with movement in a patient with hypothyroidism?

Management of Tremors with Movement in Hypothyroidism

The tremor is likely NOT caused by hypothyroidism itself—hypothyroidism does not typically cause action tremors—so you must first optimize thyroid replacement therapy and then investigate alternative causes of the tremor. 1

Key Diagnostic Distinction

Hypothyroidism causes bradycardia, delayed reflexes, and slowed movement—not tremors. 1 The ACC/AHA guidelines specifically list tremors as a clinical feature of hyperthyroidism, not hypothyroidism, describing "fine tremor of the outstretched hands" as characteristic of excess thyroid hormone. 1

Immediate Management Steps

1. Verify Thyroid Status and Treatment Adequacy

• Check TSH and free T4 levels immediately to confirm the patient is not over-replaced (iatrogenic hyperthyroidism). 2, 3
• Even slight levothyroxine overdose can cause thyrotoxicosis symptoms including tachycardia, tremor, and sweating. 2
• TSH should be in the normal reference range; dose adjustments should only occur after 6-12 weeks given levothyroxine's long half-life. 2, 4

2. Rule Out Iatrogenic Hyperthyroidism

If TSH is suppressed or free T4 is elevated, reduce levothyroxine dose. 2 This is the most common thyroid-related cause of tremor in a patient being treated for hypothyroidism. Overdose carries risks of osteoporotic fractures and atrial fibrillation, especially in elderly patients. 2

3. Investigate Alternative Causes of Action Tremor

Once euthyroid status is confirmed, the tremor requires evaluation for other etiologies:

Drug-induced tremor is extremely common and should be ruled out first:

• Sympathomimetics (decongestants, anorectics), caffeine, nicotine, cocaine, amphetamines, neuropsychiatric agents produce fine tremor with tachycardia and sweating. 1
• Consider urinary drug screen if illicit drug use is suspected. 1

Movement disorders that can coexist with hypothyroidism:

• Postural and action tremors are reported in various neurologic conditions. 1
• Essential tremor, Parkinson's disease, and drug-induced movement disorders should be considered. 1

Metabolic causes:

• Hypocalcemia may induce or worsen movement disorders and can occur with hypothyroidism, especially in patients with autoimmune polyglandular syndromes. 1
• Check calcium, parathyroid hormone, and magnesium levels. 1

Treatment Algorithm

1. Confirm biochemical euthyroidism (normal TSH and free T4) 2, 4
2. If over-replaced: Reduce levothyroxine dose and reassess tremor in 6-12 weeks 2
3. If appropriately replaced:
   • Review all medications and substances (including over-the-counter sympathomimetics, caffeine) 1
   • Check calcium, magnesium, and parathyroid hormone 1
   • Consider neurology referral if tremor persists after excluding metabolic and drug causes 1

Critical Pitfall to Avoid

Do not attribute the tremor to hypothyroidism and increase levothyroxine dose. 1, 2 This common error will worsen the tremor by inducing iatrogenic hyperthyroidism. The clinical features of hypothyroidism include bradycardia, delayed ankle reflexes, coarse skin, cold skin, and slow movement—not tremulousness. 1