Effects of vitamin D replacement on disease symptoms, sleep, depression, and fatigue in restless legs syndrome

Objective: Previous research has shown that vitamin D deficiency is more common in patients with Restless Legs Syndrome (RLS) and that symptoms are more severe in those with vitamin D deficiency. The aim of our study is to evaluate the effect of vitamin D replacement therapy on patients' symptoms by using measurements such as the International Restless Legs Syndrome Study Group (IRLSSG) symptom scale, Fatigue Severity Scale, Beck Depression Inventory, and Pittsburgh Sleep Quality Index in patients diagnosed with restless legs and found to have vitamin D deficiency before and after vitamin D supplementation. Materials and methods: Between January 2022 and April 2023, the medical records of patients who applied to the Duzce University Faculty of Medicine Neurology Outpatient Clinic with a diagnosis of Restless Legs Syndrome (RLS) were reviewed. Consequently, the vitamin D levels of patients diagnosed with RLS in our clinic were examined, and replacement therapy was administered to those with deficiencies. The effects of vitamin D supplementation on RLS symptoms were assessed using the International Restless Legs Syndrome Study Group (IRLSSG) symptom scale, the Fatigue Severity Scale for effects on fatigue levels, the Beck Depression Inventory for effects on depression levels, and the Pittsburgh Sleep Quality Index for effects on sleep quality. The study sample consisted of idiopathic RLS patients with vitamin D deficiency. After taking measurements at the time of application, patients with detected vitamin D deficiency received a weekly 50.000 IU replacement for three months. At the end of the third month after replacement, patients' control vitamin D levels were measured, and the same measurement tools were used again. Patients whose vitamin D levels did not reach the normal range were excluded from the study in the third month. Patients' conditions were observed with regular checks throughout the treatment process. Upon completion of the study, comparisons were made between the conditions before and after vitamin D therapy. Results were obtained regarding the effect of vitamin D replacement therapy on the severity of disease symptoms, sleep quality, depression, and fatigue. Results: Upon examining the initial Beck Depression Inventory (BDI) scores of the 25 patients participating in the study, the lowest score was found to be 0 and the highest score was 22. The initial average BDI score was calculated as 6.80 ± SD 5.64. After the 3-month vitamin D replacement therapy, patients' BDI scores were measured again. According to these measurements, the lowest score remained 0, and the highest score was determined to be 23. The post-treatment average BDI score was calculated as 6.84 ± SD 5.91. No statistically significant change was detected when comparing the baseline and 3-month BDI scores (p = 0.846). These results indicate that there was no significant change in patients' depression levels after vitamin D replacement therapy. Upon examining the initial International Restless Legs Syndrome Study Group (IRLSSG) symptom scale scores of the 25 patients participating in the study, the lowest score was found to be 5 and the highest score was 29. The initial average IRLSSG symptom scale score was calculated as 15.36 ± SD 6.75. After the 3-month vitamin D replacement therapy, patients' IRLSSG symptom scale scores were measured again. According to these measurements, the lowest score was 5 and the highest score remained 29. The post-treatment average IRLSSG symptom scale score was calculated as 14.28 ± SD 6.22. The IRLSSG symptom scale scores after replacement therapy were significantly lower compared to baseline (p = 0.019). Upon examining the initial Pittsburgh Sleep Quality Index (PSQI) scores of the 25 patients participating in the study, the lowest score was found to be 9 and the highest score was 17. The initial average PSQI score was 11.76 ± SD 1.98. After the vitamin D replacement therapy, patients' PSQI scores were determined to have a minimum value of 7 and a maximum value of 17. The post-treatment average PSQI score was 11.52 ± SD 2.30. There was no statistically significant difference between the baseline and 3-month PSQI scores (p = 0.242). When analyzing the initial Fatigue Severity Scale (FSS) scores of the 25 patients participating in the study, the lowest score was measured to be 1 and the highest score was 55. The initial average FSS score was calculated as 19.32 ± SD 12.34. After the 3-month vitamin D replacement therapy, patients' FSS scores were re-evaluated. According to these measurements, the lowest score was 1, and the highest score remained 55. The post-treatment average FSS score was determined as 18.24 ± SD 11.32. When comparing the baseline and 3-month FSS scores, the 3-month FSS scores were slightly decreased compared to baseline. Although statistical significance was not achieved, p = 0.058 indicated a decrease close to significance. Conclusion: Vitamin D replacement therapy has been shown to have a positive effect on the severity of RLS symptoms, while it did not have a significant effect on sleep quality and depression. A limited effect on fatigue levels was observed. Vitamin D levels in idiopathic RLS patients seem to be associated with the severity of disease symptoms. Monitoring vitamin D levels in RLS patients and administering replacement therapy in those with deficiencies may suggest a reduction in the severity of disease symptoms. Keywords: Restless Legs Syndrome, Vitamin D, Depression, Fatigue, Sleep Quality.