Can a ferritin level of 27 ng/mL cause paresthesia (crawling sensations)?

Can Low Ferritin Cause Crawling Sensations (Paresthesia)?

Yes, a ferritin level of 27 ng/mL can cause paresthesia including crawling sensations, as this level is considered low and associated with iron deficiency which can manifest as restless legs syndrome (RLS) with sensory symptoms. 1

Understanding Ferritin Levels and Neurological Symptoms

Ferritin Interpretation:

• A ferritin level of 27 ng/mL is considered low according to clinical guidelines
• Values less than 50 ng/mL are consistent with a diagnosis of RLS 1
• For iron deficiency diagnosis:
  • Without inflammation: <30 μg/L indicates deficiency 2
  • With inflammation: <100 μg/L may still reflect deficiency 2

Neurological Connection:

Iron plays a critical role in neurological function, particularly in dopaminergic pathways. The impairment of dopamine transport in the substantia nigra due to reduced intracellular iron appears to play a critical role in patients with RLS 1.

Clinical Manifestations of Low Ferritin

Sensory Symptoms:

• Uncomfortable or unpleasant sensations in the legs
• Crawling, creeping, or tingling sensations
• Urge to move the legs
• Symptoms worsen during periods of rest or inactivity
• Symptoms partially or totally relieved by movement
• Symptoms worse in the evening or night 1

Diagnostic Criteria for RLS:

1. Urge to move legs accompanied by uncomfortable/unpleasant sensations
2. Symptoms begin or worsen during periods of rest
3. Symptoms partially or totally relieved by movement
4. Symptoms worse in evening or night 1

Assessment and Management

Evaluation:

• Serum ferritin is recommended for all patients with suspected RLS
• Physical examination is usually unremarkable in primary RLS
• Differential diagnosis includes peripheral neuropathies, vascular disease, neuroleptic-induced akathesias, arthritides, and venous varicosities 1

Treatment Approach:

1. Iron Supplementation:

   • Indicated when ferritin is <50 ng/mL 1
   • Oral iron therapy: 60-120 mg elemental iron daily 2
   • Goal: increase hemoglobin by 1-2 g/dL within 4-8 weeks 2
   • Target ferritin: ≥50 ng/mL 2

2. Pharmacologic Therapy (if symptoms persist):

   • First-line: Dopaminergic agents (ropinirole, pramipexole)
   • Second-line: Opioids, benzodiazepines, anticonvulsants 1

Important Considerations

Pitfalls to Avoid:

• Not recognizing that ferritin <50 ng/mL can cause neurological symptoms even when not severely low
• Overlooking that normal iron levels with low ferritin can still cause RLS symptoms 3
• Failing to consider that inflammation may mask iron deficiency by falsely elevating ferritin levels 2
• Stopping iron supplementation too early (should continue 2-3 months after normalization) 2

Monitoring:

• Check hemoglobin after 4 weeks to assess response
• Complete iron studies 4-8 weeks after treatment
• Target parameters: ferritin ≥50 ng/mL, transferrin saturation >20% 2

Low ferritin levels should be addressed promptly, as correcting iron deficiency can significantly improve neurological symptoms including paresthesia and crawling sensations, thereby improving quality of life and reducing morbidity associated with these uncomfortable symptoms.