Serum Ferritin Thresholds

Serum ferritin provides important information about iron levels in the body. In addition, altered levels of serum ferritin may point to an inflammatory state, potential ferritin leak (for example, in the case of liver disease or hemophagocytic lymphohistiocytosis [HLH]), or rarely a congenital hyperferritinemia cataract syndrome. As physicians, we tend to compartmentalize our approaches to low ferritin and high ferritin levels. Here, we consider the full spectrum of changes, and how certain ferritin thresholds may be used to clinical advantage.

• Normal range for serum ferritin is lower in women compared with men not because lower iron stores are healthier in women, but because normal ranges in women are derived from populations of “healthy” adults that include individuals with undiagnosed iron deficiency (which is much more common in premenopausal women than men).
• Several ferritin thresholds are clinically useful:
  • A low ferritin (<15 ng/ml) is virtually diagnostic of iron deficiency.
  • A ferritin >100 ng/ml argues strongly against iron deficiency except in patients with renal dysfunction.
  • A high ferritin may indicate:
    • Inflammation, including:
      • Connective tissue disease
      • Infection
      • Cancer
      • HLH
    • Iron overload
      • Hereditary hemochromatosis
      • Transfusional iron overload
      • Ineffective erythropoiesis (e.g,, thalassemia)
    • Liver disease
    • Alcohol use disorder
    • Hyperferritinemia-cataract syndrome (rare)