Prevalence of Restless Leg Syndrome and Its Association With Iron Deficiency in Patients With Chronic Kidney Disease: A Cross-Sectional Observational Study

Abstract

Background: Restless leg syndrome (RLS), or Willis-Ekbom disease, is a common yet underdiagnosed neurological disorder characterized by an uncontrollable urge to move the legs, often accompanied by unpleasant sensations. Symptoms are worse during rest and at night, significantly affecting sleep and quality of life. Its prevalence is notably higher among patients with chronic kidney disease (CKD), particularly those undergoing dialysis, and is closely linked with disturbances in iron metabolism. Iron is vital for dopamine synthesis, and its deficiency - common in CKD due to inflammation, poor intake, and blood loss - has been implicated in RLS pathogenesis. This study investigates the prevalence of RLS among CKD patients across various treatment modalities and its association with iron deficiency using serum ferritin, transferrin saturation (TSAT), serum iron, and total iron-binding capacity (TIBC).

Methods: A cross-sectional observational study was conducted at Madras Medical College, Chennai, over six months, involving 150 adult CKD patients (Stages 3-5). Participants were grouped as hemodialysis-dependent (HD), peritoneal dialysis-dependent (PD), conservatively managed (non-dialysis), and post-renal transplant. Patients with non-CKD neurological/psychiatric disorders or those on RLS-inducing medications were excluded. RLS diagnosis was based on the International Restless Legs Syndrome Study Group (IRLSSG) criteria. Clinical interviews, case records, and laboratory tests were used for data collection. Statistical analysis was performed using SPSS (IBM Corp., Armonk, NY, USA), with significance set at p < 0.05.

Results: The average participant age was 51.6 ± 12.3 years; 58% were male. The distribution included HD (40%), conservative (28%), PD (18%), and transplant (14%) groups. RLS was diagnosed in 42% of patients (63 out of 150), with the highest prevalence in HD patients (51.7%), followed by PD (40.7%), conservative (26.2%), and transplant (23.8%). Elderly patients (≥60 years) and females had higher RLS prevalence (46.7% and 47.6%, respectively). Diabetics were more affected than non-diabetics (47.8% vs. 37%). Patients with RLS had significantly lower iron indices: mean serum ferritin (88.4 ± 25.6 ng/mL vs. 126.7 ± 30.1 ng/mL), TSAT (16.3 ± 4.7% vs. 22.1 ± 5.6%), and serum iron (48.2 ± 11.4 µg/dL vs. 64.7 ± 13.1 µg/dL). TIBC was higher in RLS patients (295 ± 36 µg/dL vs. 273 ± 30 µg/dL). These findings were statistically significant (p < 0.01).

Conclusion: RLS is highly prevalent among CKD patients, especially those on dialysis, and shows a strong association with iron deficiency. Reduced serum ferritin, TSAT, and serum iron levels indicate that impaired iron metabolism contributes significantly to RLS in this population. Functional iron deficiency, even with normal ferritin, may underlie persistent symptoms. Early recognition and targeted iron therapy could reduce RLS burden and improve sleep, mood, and quality of life in CKD patients. Further multicenter studies are needed to validate these findings and develop standardized management protocols.

Keywords: chronic kidney disease (ckd); cross sectional studies; iron deficiency anemia (ida); manganese and dopamine transporter; s: restless leg syndrome.