Ferritin (and Iron Studies)

•Observational— U-shape mortality

What it measures

Ferritin is the intracellular iron-storage protein. Serum ferritin correlates with total body iron stores when inflammation is absent. Crucially, it’s also an acute-phase reactant — rises with infection, inflammation, liver disease, malignancy, and metabolic syndrome independent of iron status.

Iron-deficiency thresholds

Ferritin <30 ng/mL is iron-deficient (sensitivity ~90%). In women with heavy menses, athletes, vegetarians, post-bariatric patients, and chronic NSAID users, low ferritin without anaemia is common and worth treating.

Iron-overload

Hereditary haemochromatosis (HFE C282Y homozygous) affects ~1 in 250 Europeans; ferritin >300 with elevated transferrin saturation warrants HFE testing. Untreated overload causes cirrhosis, diabetes, arthritis, cardiomyopathy, gonadal dysfunction.

Interpretation requires inflammation context

If hsCRP or other inflammation markers are elevated, ferritin is hard to interpret. Consider transferrin saturation (TSAT) and soluble transferrin receptor for a clearer picture.

Related entries

hsCRP, Cardiovascular disease, Vitamin B12.