Abstract
STUDY OBJECTIVES: Vitamin D deficiency is associated with restless legs syndrome (RLS). However, a cutoff value for serum 25-hydroxyvitamin D (25[OH]D) level associated with RLS has yet to be clearly determined. We evaluated the association between 25(OH)D and RLS in pregnant women. METHODS: Data from 203 pregnant women were evaluated using blood samples taken in the third trimester. Liquid chromatography-tandem mass spectrometry and ligand binding assays were used to measure 25(OH)D. RLS was diagnosed based on International Classification of Sleep Disorders, third edition, criteria. The cutoff value for serum 25(OH)D associated with RLS was explored using receiver operating characteristic (ROC) curve and classification and regression tree (CART) analyses. RESULTS: The results of liquid chromatography-tandem mass spectrometry (x) and ligand binding assays (y) for serum 25(OH)D in the RLS (n = 35, 17.2%) and non-RLS (n = 168) groups showed a relationship of y = -2.65 + 0.08x . The RLS group showed lower serum 25(OH)D and folate levels. ROC curve and CART analyses revealed cutoff values of 10-12.7 ng/mL and 6.6-7.2 ng/mL for 25(OH)D and folate, respectively. Of the 5 women with RLS symptoms persisting at a moderate-to-severe level after delivery, 4 had 25(OH)D levels < 10 ng/mL and all had folate levels < 6 ng/mL. CONCLUSIONS: Vitamin D and folate deficiency were associated with RLS in pregnant women and may be associated with persistent moderate-to-severe postpartum RLS symptomatology; it is essential to examine associations with RLS while accounting for measurement methods and assay systems. CITATION: Miyazaki A, Takahashi M, Shuo T, Eto H, Kondo H. Determination of optimal 25-hydroxyvitamin D cutoff values for the evaluation of restless legs syndrome among pregnant women. J Clin Sleep Med. 2023;19(1):73-83.