Low Serum Ferritin as the Root Trigger
Peripheral iron stores set the ceiling for brain iron delivery.
- <50: Ferritin threshold (ng/mL RLS risk zone)
- 30–300: Normal range (ng/mL typical adult)
- ~25%: Prevalence link (RLS patients iron deficient)
- Serum ferritin: Screening test (first-line lab check)
Peripheral iron status
Placeholder: low ferritin reflects depleted total-body iron stores.
Brain Iron Depletion in the Basal Ganglia
Regional brain iron tracks peripheral ferritin with a lag.
- Substantia nigra: Key region (iron-rich dopaminergic hub)
- MRI T2*: Imaging marker (detects regional iron loss)
- Transferrin: Transport protein (crosses blood-brain barrier)
- Reduced: CSF ferritin (in RLS patients)
Regional brain iron
Placeholder: basal ganglia iron pools shrink under systemic deficiency.
Iron-Dependent Dopamine Synthesis Falters
Iron is a cofactor for the dopamine-synthesis enzyme pathway.
- Tyrosine hydroxylase: Cofactor enzyme (iron-dependent step)
- Evening worsening: Circadian pattern (matches RLS symptom timing)
- D2 downregulation: Receptor change (postsynaptic adaptation)
- Dopamine agonists: Treatment clue (partially relieve symptoms)
Dopamine pathway disruption
Placeholder: reduced iron impairs dopaminergic neurotransmission.
From Dysfunction to Restless Legs Sensation
Circuit imbalance produces the urge to move the legs.
- Urge to move: Core symptom (worse at rest, evening)
- Movement relieves: Relief pattern (temporary symptom relief)
- Frequent: Sleep disruption (periodic limb movements)
- Clinical criteria: Diagnosis basis (IRLSSG four-point checklist)
Symptom expression
Placeholder: restlessness pulses correlate with dopaminergic deficit severity.
Symptom Improvement with Iron Repletion
Restoring ferritin gradually restores basal ganglia function.
- Oral/IV iron: Therapy route (depends on severity)
- Weeks: Response time (gradual symptom easing)
- >75: Target ferritin (ng/mL treatment goal)
- Reduced severity: Outcome (in responders)
Therapeutic response
Placeholder: iron therapy over weeks lowers RLS severity scores.
Placeholder: sustained iron repletion improves sleep and symptom scores.