Lower serum ferritin levels are strongly correlated with greater RLS severity in drug-naive patients with idiopathic RLS, even when ferritin is within the normal laboratory range.
In a cross-sectional study of 113 drug-naive idiopathic RLS patients with serum ferritin levels within the normal range (22-322 μg/L), multiple regression analysis identified serum ferritin (p < 0.001) and age (p = 0.001) as independent predictors of symptom severity. A very strong negative correlation was found between ferritin level and RLS severity, suggesting ferritin should be evaluated as a continuous parameter rather than a threshold.
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Lower serum ferritin levels are strongly correlated with greater RLS severity in drug-naive patients with idiopathic RLS, even when ferritin is within the normal laboratory range. The current body of evidence comprises 1 study. EvidenceHub rates the overall confidence at 34/100 (low).
The Claim
Lower serum ferritin levels are strongly correlated with greater RLS severity in drug-naive patients with idiopathic RLS, even when ferritin is within the normal laboratory range.
This conclusion is most relevant to: 113 drug-naive patients with idiopathic Restless Legs Syndrome, with serum ferritin levels within the laboratory reference range (22-322 μg/L), mean age 52 ± 13.8 years.
What the Research Shows
The conclusion draws on 1 linked study. Highlights from the cited literature:
- ▸Is "normal" ferritin truly enough? Strong correlation between iron stores and RLS severity in patients with normal ferritin levels. (Sleep medicine, 2026) —
How It Works
The proposed biological pathway:
- ▸Low peripheral iron stores (ferritin) reduce brain iron availability
- ▸Decreased brain iron impairs dopamine synthesis and function
- ▸Dopaminergic dysfunction in sensorimotor circuits triggers RLS symptoms
- ▸Result: Lower ferritin correlates with higher RLS severity
Who Might Benefit
Evidence fit by population:
- ▸113 drug-naive patients with idiopathic Restless Legs Syndrome, with serum ferritin levels within the laboratory reference range (22-322 μg/L), mean age 52 ± 13.8 years
Recommended Dose
N/A
Limitations & Caveats
Important context when interpreting this evidence:
- ▸Cross-sectional design prevents establishing causality between ferritin levels and RLS severity
- ▸Single-center study with a relatively small sample size (n=113) may limit generalizability
Frequently Asked Questions
What ferritin level is considered 'normal' for RLS patients?▼
The study used a laboratory reference range of 22-322 μg/L as 'normal,' but found that even within this range, lower ferritin levels were strongly associated with worse RLS symptoms.
Does iron supplementation help RLS symptoms in patients with normal ferritin?▼
This study did not test iron supplementation; it only observed a correlation between ferritin levels and symptom severity. Clinical trials would be needed to determine if raising ferritin improves symptoms.
What other factors predicted RLS severity in this study?▼
Age was also an independent predictor of severity (p=0.001), but sex, hemoglobin, vitamin D, and other comorbidities did not show independent effects.
How was RLS severity measured in this study?▼
Severity was assessed by a neurologist using the International Restless Legs Syndrome Rating Scale, a validated tool for quantifying RLS symptom severity.
References
- 1.Tanoğlu C, Ersoy A. “Is "normal" ferritin truly enough? Strong correlation between iron stores and RLS severity in patients with normal ferritin levels..” Sleep medicine, 2026. PMID: 42119338 DOI: 10.1016/j.sleep.2026.109008