Ferritin: When Too Low and Too High Both Matter

What ferritin is

Ferritin is the protein that stores iron in cells. Serum ferritin reflects body iron stores, but it's also an acute-phase reactant that rises with inflammation independent of iron status.

Low ferritin

Low ferritin (<30 ng/mL) indicates depleted iron stores. Symptoms before anemia develops:

• Fatigue
• Hair loss / shedding
• Exercise intolerance
• Restless legs syndrome
• Pica (cravings for ice, etc.)
• Brain fog
• Cold extremities

Common in women with menstrual losses, vegetarians, athletes, GI losses.

High ferritin

Elevated ferritin can reflect:

• Inflammation (acute or chronic)
• Fatty liver disease
• Metabolic syndrome
• Hemochromatosis (genetic iron overload, affects ~1 in 200)
• Excess iron supplementation
• Repeated transfusions
• Cancer (rare)

Very high ferritin (>500) warrants further evaluation including iron saturation and genetic testing for hemochromatosis.

Optimal range

• Women: 50-100 ng/mL
• Men: 70-150 ng/mL
• Below 30: deficient (consider supplementation)
• Above 200: investigate cause

Inflammation confounds

Because ferritin rises with inflammation, a "normal" ferritin in an inflamed patient may mask iron deficiency. Companion testing:

• Iron saturation (transferrin saturation)
• Total iron
• Transferrin
• hs-CRP (to assess inflammation)

If hs-CRP is elevated and ferritin is borderline-low, iron deficiency may still be present.

Treatment approaches

For iron deficiency:

• Oral iron (ferrous sulfate, ferrous bisglycinate)
• Take with vitamin C, away from coffee/calcium
• Re-test at 8-12 weeks
• IV iron for poor absorbers or severe deficiency

For elevated ferritin from overload:

• Therapeutic phlebotomy
• Genetic testing for hemochromatosis
• Avoid iron supplements and high-iron foods

Bottom line

Ferritin reflects iron stores but is also an inflammation marker. Both extremes produce clinical issues. Optimal range is moderate. Always interpret in context of inflammation markers and iron saturation.