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Restless legs syndrome (RLS)
Restless legs syndrome is an unpleasant urge to move the legs that comes on at rest and in the evening and is relieved by movement — and every patient has iron stores checked, because low iron is a common, correctable cause.
Why it matters in the exam
Questions present a patient who struggles to fall asleep because of "currents" or "ants" in the legs that force him to get up and walk, sometimes in pregnancy, kidney failure or iron-deficiency anaemia. They test the five diagnostic criteria, the first test (ferritin and transferrin saturation), the drugs that worsen it (antihistamines, antidepressants, antipsychotics, metoclopramide), and treatment according to current guidelines: iron when ferritin is 75 mcg/L or less, and alpha-2-delta drugs (gabapentin, pregabalin) as first-line. An important distractor is a dopamine agonist as long-term first-line treatment, which causes "augmentation" — worsening, earlier onset and spread to the arms. Distinguish it from night cramps (muscle pain, no urge) and from drug-induced akathisia (general restlessness, not linked to the evening). Most patients also have periodic limb movements in sleep.
Key points
- RLS: an urge to move the legs at rest and in the evening, relieved by movement.
- Check ferritin and transferrin saturation in every patient.
- Iron when ferritin is 75 mcg/L or less; intravenous when ferritin is 100 or less and oral iron is ineffective.
- First line: gabapentin, gabapentin enacarbil or pregabalin.
- Dopamine agonists cause augmentation and are not recommended for routine use.
Summary table
| Aspect | Core | Exam detail |
|---|---|---|
| Diagnosis | An urge to move the legs, usually with unpleasant leg sensations; starts or gets worse at rest; relieved by movement; worse in the evening and at night; not explained by another condition | Clinical diagnosis; no sleep study needed |
| Causes and aggravators | Iron deficiency, kidney failure, pregnancy, neuropathy; antihistamines, antidepressants, antipsychotics, metoclopramide | Ferritin and transferrin saturation for every patient |
| Iron | Oral iron when ferritin is 75 mcg/L or less and transferrin saturation is below 45 percent; intravenous iron when ferritin is 100 or less or oral iron is ineffective | The thresholds are higher than for ordinary anaemia |
| Drugs | First line: gabapentin, gabapentin enacarbil or pregabalin | Dopamine agonists (pramipexole, ropinirole, rotigotine) are not recommended for routine use because of augmentation |
| Augmentation | Greater intensity, earlier onset in the day, spread to the arms during dopaminergic treatment | Taper the agonist, correct iron and switch to an alpha-2-delta drug |
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Sources
- AASM Clinical Practice Guideline: Treatment of Restless Legs Syndrome and Periodic Limb Movement Disorder, 2024 — Iron, alpha-2-delta ligands and dopamine agonists
- IRLSSG Consensus Diagnostic Criteria for Restless Legs Syndrome, 2014 — Essential diagnostic criteria
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.