Iron deficiency is the most common nutritional deficiency globally, affecting an estimated 1 in 3 women of reproductive age. Many people have iron deficiency before developing anemia — symptoms can occur with low ferritin even when hemoglobin is normal. The signs of iron deficiency are diverse. This guide covers symptoms, causes, and treatment. Discuss with your healthcare provider.
Common symptoms
- Fatigue (most common)
- Pale skin (with anemia)
- Shortness of breath on exertion
- Brittle nails, spoon-shaped nails (severe)
- Hair loss
- Restless legs syndrome
- Pica (cravings for ice or non-food items)
- Cognitive issues
- Cold intolerance
- Headaches
Many symptoms can occur with low iron stores (low ferritin) before frank anemia develops.
Causes
- Menstrual blood loss (most common in women)
- GI bleeding (most common in men, postmenopausal women)
- Inadequate dietary iron
- Pregnancy
- Malabsorption (celiac, gastric bypass)
- Frequent blood donation
- Heavy exercise (some athletes)
For non-menstruating adults, iron deficiency warrants GI evaluation.
Diagnosis
Most sensitive: ferritin (iron storage marker).
- Ferritin under 30 ng/mL: likely deficiency
- Ferritin under 15 ng/mL: definite deficiency
- Many clinicians consider under 50-100 ng/mL relatively low for symptomatic patients
See our ferritin test guide and iron studies guide.
Treatment
Oral iron supplementation:
- Ferrous sulfate, gluconate, or fumarate
- Take with vitamin C, away from coffee/tea/calcium
- Every-other-day dosing may be better tolerated and better absorbed
- 3-6 months to replenish stores
- IV iron for severe deficiency or oral intolerance
Frequently Asked Questions
Can I be iron deficient without anemia?
Yes. Symptoms often occur with low ferritin before anemia develops.
Why is restless legs related to iron?
Iron deficiency is a known cause/contributor. Treatment often improves RLS.
Should I take iron prophylactically?
Generally only if at risk (menstruating, pregnant, vegetarian). Iron overload is harmful.
How long does treatment take?
3-6 months to replenish stores. Symptoms improve in weeks-months.
Why are women more affected?
Menstrual blood loss. Pregnancy further depletes stores.
The bottom line on iron deficiency
Iron deficiency is common, especially in menstruating women. Symptoms can occur before anemia. Diagnosis by ferritin. Treatment with oral iron typically effective. Discuss with healthcare provider.