My right leg shakes continuously throughout the night; what could be causing it and how should I evaluate and treat it?

Evaluation and Management of Nocturnal Leg Shaking

Most Likely Diagnosis: Restless Legs Syndrome (RLS)

Your right leg shaking continuously at night is most consistent with Restless Legs Syndrome (RLS), which requires immediate evaluation of iron stores (ferritin level) and consideration of dopaminergic or gabapentinoid therapy if conservative measures fail. 1, 2

Critical Diagnostic Questions to Ask Yourself

To differentiate RLS from other nocturnal leg conditions, answer these specific questions:

• "What does it feel like?" – RLS presents as an uncomfortable urge to move with dysesthesias (crawling, creeping sensations), NOT painful muscle tightening 3, 1
• "Is it worse in the evening or at night?" – RLS symptoms characteristically worsen at night and with rest 3, 2
• "Does movement relieve it?" – RLS improves with ANY movement (walking, stretching, rubbing), but symptoms return within minutes after stopping movement 3, 1
• "Does your bed partner see twitching or kicking?" – If yes, this suggests periodic limb movements of sleep (PLMS), present in up to 90% of RLS patients 1, 2

Essential Initial Workup

Check serum ferritin immediately – This is the single most important test:

• Ferritin <50 ng/mL warrants iron supplementation, as iron deficiency is strongly associated with RLS 1, 2
• Some guidelines suggest supplementation even when ferritin is <75 ng/mL 3

Additional laboratory tests to order:

• Complete metabolic panel (renal function) – chronic kidney disease is associated with RLS 3, 4
• Thyroid function tests 4
• HbA1c – diabetic neuropathy can mimic RLS 4

Medication review is mandatory:

• STOP or switch these medications if possible: tricyclic antidepressants, SSRIs, lithium, dopamine antagonists (antiemetics, antipsychotics) – all worsen RLS 1, 4
• Diuretics and calcium channel blockers can also trigger leg symptoms 1, 4

Physical Examination Focus

• Neurological exam: Look for peripheral neuropathy signs (reduced sensation, absent reflexes, weakness) – neuropathy is strongly associated with nocturnal leg symptoms 1, 4
• Vascular assessment: Check pedal pulses and signs of arterial insufficiency – peripheral arterial disease causes nocturnal leg symptoms 1
• Check for peripheral edema – suggests fluid retention contributing to symptoms 3

First-Line Treatment Algorithm

Step 1: Non-Pharmacological Measures (Try First)

• Avoid prolonged positioning at end range of joints 4
• Ensure adequate hydration before bedtime 4
• Avoid caffeine and alcohol (diuretic effects worsen symptoms) 3

Step 2: Iron Supplementation (If Ferritin <50-75 ng/mL)

• Oral iron supplementation is first-line when ferritin is low 3, 1
• Consider intravenous iron infusion if oral iron fails or symptoms are severe 5

Step 3: Pharmacological Treatment (If Symptoms Persist)

First-line pharmacological options:

• Gabapentin or pregabalin – preferred initial agents 2, 5
• Gabapentin enacarbil – specifically recommended 2

Alternative first-line (use with caution):

• Dopamine agonists (pramipexole, ropinirole, rotigotine) – effective but carry risk of "augmentation" (worsening symptoms over time with earlier onset and spread to arms) 6, 5
• Levodopa compounds – may be used short-term but augmentation risk is high 2, 6

Second-line options:

• Opioids (tramadol, oxycodone, methadone) – reserved for severe, refractory cases 5

Common Pitfalls to Avoid

• Do NOT assume this is simple "nocturnal leg cramps" – True cramps are PAINFUL muscle contractions relieved specifically by stretching the affected muscle, not general movement 1
• Do NOT order polysomnography routinely – RLS diagnosis is clinical; sleep studies are only needed if periodic limb movement disorder (PLMD) is suspected as the primary problem or diagnosis is unclear 1, 2
• Do NOT start dopamine agonists without discussing augmentation risk – Up to 90% of RLS patients may develop augmentation, requiring dose escalation or medication change 6, 5
• Do NOT ignore medication triggers – Many common medications (antidepressants, antihistamines, antiemetics) directly worsen RLS 1, 4

When to Refer

Refer to neurology if:

• "Suspicious" neurological symptoms are present: numbness, weakness, speech disturbance, gait abnormality, memory loss, or autonomic symptoms 3
• Symptoms are refractory to first-line treatments 3
• Diagnosis remains unclear after initial evaluation 3

Refer to sleep clinic if:

• Bed partner reports significant kicking/twitching and daytime fatigue persists despite treatment (suggests PLMD requiring polysomnography) 3, 2