Ferritin — Optimal vs Normal Range and Why It Matters
Ferritin measures your body's stored iron. Lab “normal” ranges go as low as 20 ng/mL, but fatigue starts below 50, hair loss below 40, and optimal function requires 70–150 ng/mL. An estimated 30% of menstruating women have ferritin below 50 — technically “normal” but functionally deficient.
What Ferritin Measures
Ferritin is a protein that stores iron inside your cells. A blood ferritin test reflects how much iron your body has in reserve — not how much is circulating. It's the most sensitive marker for early iron depletion, dropping months or years before hemoglobin falls and anemia is diagnosed.
Iron is a cofactor for over 300 enzymatic reactions, including dopamine synthesis (via tyrosine hydroxylase), thyroid hormone conversion (T4→T3 via thyroid peroxidase), and immune cell proliferation (via ribonucleotide reductase). When ferritin drops, these systems slow down — often before any lab flags it as abnormal.
“Normal” vs Optimal: The Gap Your Lab Report Doesn't Show
| Range | Female | Male |
|---|---|---|
| Lab “normal” | 12–150 ng/mL | 12–300 ng/mL |
| Optimal | 70–150 ng/mL | 70–150 ng/mL |
A ferritin of 22 ng/mL is reported as “normal” on standard lab work. But research in clinical endocrinology and hematology consistently shows that symptoms begin well above the lab floor: fatigue below 50, hair loss below 40, restless legs below 75, and impaired cognitive function below 50. The lab range was designed to detect severe anemia — not to identify when you're functioning below your potential.
Symptoms of Low Ferritin
Because iron is involved in dopamine synthesis, thyroid function, and oxygen transport, low ferritin produces a wide range of symptoms that are frequently misdiagnosed:
- Fatigue and exercise intolerance — the most common symptom, often attributed to stress or depression
- Hair loss (telogen effluvium) — accelerated shedding, often noticed 3-6 months after ferritin drops
- Brain fog and poor concentration — iron is required for dopamine production
- Restless legs syndrome — strong association with ferritin below 75 ng/mL
- Shortness of breath on exertion — reduced oxygen-carrying capacity
- Heart palpitations and tachycardia — compensatory increase in heart rate
- Cold intolerance — iron is needed for thyroid hormone production
- Brittle nails — a classic but often overlooked sign
Medications That Deplete Ferritin
Several common medications reduce iron absorption or increase iron loss. If you're on any of these and your ferritin is suboptimal, the medication may be contributing:
PPIs (Omeprazole, Nexium, Pantoprazole)
Reduce stomach acid needed for iron absorption
H2 blockers (Ranitidine, Famotidine)
Same mechanism — reduced acid, reduced absorption
NSAIDs (long-term use)
Can cause occult GI bleeding, increasing iron loss
Antacids (calcium-based)
Calcium competes with iron for absorption
Check your medications to see all nutrient depletions — free, no signup required.
Top Foods to Improve Ferritin
Heme iron (from animal sources) is absorbed 2-3x more efficiently than non-heme iron (plant sources). Vitamin C taken with iron-rich foods increases absorption by up to 6x. Calcium, tea, and coffee inhibit absorption — separate by 2 hours.
| Food | Iron per serving | Type |
|---|---|---|
| Beef liver (3 oz) | 5.2 mg | Heme |
| Oysters (3 oz) | 7.8 mg | Heme |
| Beef steak (3 oz) | 2.6 mg | Heme |
| Lentils (1 cup cooked) | 6.6 mg | Non-heme |
| Spinach (1 cup cooked) | 6.4 mg | Non-heme |
| Dark chocolate (1 oz) | 3.4 mg | Non-heme |
Source: USDA FoodData Central (658,000+ entries)
How Kelda Analyzes Ferritin
Kelda checks your ferritin against evidence-based optimal ranges (70–150 ng/mL), not the wide lab range. It cross-references your medications against known depletions that affect iron. If you're on a PPI and your ferritin is trending down, Kelda flags the temporal correlation — your ferritin was higher before the PPI started.
Every finding traces to specific molecular database entries, not AI opinion. Same query, same data, same answer — every time.
Frequently Asked Questions
What is a good ferritin level?
Optimal ferritin is 70–150 ng/mL for both men and women. Below 50 is associated with fatigue, below 40 with hair loss, and below 75 with restless legs syndrome.
Can ferritin be too high?
Yes. Ferritin above 200 ng/mL in women or 300 ng/mL in men may indicate iron overload, inflammation, or liver disease. High ferritin should be evaluated by a physician.
How often should I test ferritin?
Every 3–6 months if supplementing iron. Once yearly if stable. More frequently if on medications that deplete iron (PPIs, NSAIDs).
Should I take iron every day?
Every-other-day dosing may be more effective. Hepcidin (a hormone that blocks iron absorption) rises for 24 hours after each dose, so alternate-day dosing allows better absorption per dose.
Check your ferritin against optimal ranges
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Upload My LabsEducational content — not medical advice. Always consult your healthcare provider before making changes to your health regimen. Last updated: March 2026.