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An urge to move with L-thyroxine: clinical, biochemical, and polysomnographic correlation
Eng-King Tan1, Su-Chin Ho, Leonard Koh
1Department of Neurology, Singapore General Hospital, Singapore. gnrtek@sgh.com.sg
Abstract:
We report on the cause and effect relationship of restless legs syndrome (RLS) with L-thyroxine treatment in a hypothyroid patient with low serum ferritin. Upon challenge and withdrawal of L-thyroxine, there was a significant change in the International Restless Legs Syndrome Study Group severity score (26/40 to 6/40), the periodic limb movements (PMLS) index (20/hour to 10/hour), the number of arousals due to PLMS (59 to 22), sleep efficiency (74 to 85%), and biochemical parameters. RLS symptoms can complicate thyroxine replacement in at-risk hypothyroid patients with low serum ferritin. Early diagnosis and iron replacement could significantly reduce patient morbidity.
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