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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.

Q: 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.

Q: 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.

Q: 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.

Q: 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.

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.

Last updated: Aug 26, 2026•0 RCTs•📖 Read as article →

Evidence Score

Evidence Score34/100

Human RCT☆☆☆☆☆

Meta-analysis☆☆☆☆☆

Mechanism★★★★★

Safety★★★★☆

Confidencelow

Study Evidence

Study 1. Is "normal" ferritin truly enough? Strong correlation between iron stores and RLS severity in patients with normal ferritin levels.

observational

Tanoğlu C, Ersoy A · Sleep medicine (2026)

Participants: N/A

Duration: N/A (cross-sectional)

Intervention: None (observational study measuring serum ferritin levels and other biochemical parameters)

Outcome: RLS symptom severity measured by the International Restless Legs Syndrome Rating Scale

Effect Size: N/A (regression coefficients not reported in abstract)

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

Result:

PubMed: 42119338 DOI: 10.1016/j.sleep.2026.109008

Mechanism Graph

Low peripheral iron stores (ferritin) reduce brain iron availability

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Decreased brain iron impairs dopamine synthesis and function

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Dopaminergic dysfunction in sensorimotor circuits triggers RLS symptoms

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Result: Lower ferritin correlates with higher RLS severity

Limitations

⚠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.

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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

Disclaimer: This content is for educational purposes only and is not medical advice. Evidence scores reflect the quality and quantity of available research, not clinical recommendations. Always consult a healthcare professional before starting any supplement or intervention.