Restless Legs Syndrome in a Patient with Iron Deficiency
A 58-year-old woman presents with a 6-month history of an uncomfortable urge to move her legs, primarily in the evenings and at rest, which is relieved by walking. She reports difficulty falling asleep and daytime fatigue. Her ferritin level is 18 ng/mL (normal 15-150), and hemoglobin is 12.5 g/dL. She has no other medical conditions and takes no medications. She has tried lifestyle modifications without relief. Her symptoms occur at least 3 times per week and significantly affect her sleep.
1. What is the most appropriate initial management for this patient's restless legs syndrome (RLS)?
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This patient has RLS with a ferritin level of 18 ng/mL, which is below the threshold of 75-100 ng/mL often considered for iron supplementation. The most appropriate initial management is iron replacement therapy, typically oral iron (e.g., ferrous sulfate 325 mg with vitamin C) taken on an empty stomach, with reassessment of ferritin after 3 months. Non-pharmacologic measures (sleep hygiene, avoiding triggers) should continue. Dopamine agonists are not first-line when iron deficiency is present because correcting iron stores may improve symptoms and avoid augmentation. Therefore, iron therapy is the correct initial step.
2. If the patient's ferritin level were 120 ng/mL, how would your management change?
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If ferritin were 120 ng/mL, iron deficiency is less likely, and iron supplementation is not indicated. In that case, first-line pharmacologic therapy for moderate-to-severe RLS would be a dopamine agonist (e.g., pramipexole, ropinirole) or an alpha-2-delta ligand (gabapentin enacarbil, pregabalin). However, because of the risk of augmentation with dopamine agonists, alpha-2-delta ligands are often preferred, especially if the patient has painful symptoms or sleep disturbance. Non-pharmacologic measures should continue. Thus, management would shift to a dopamine agonist or alpha-2-delta ligand, with close monitoring for augmentation.