What does the Ferritin, Serum test measure?

Why is Ferritin, Serum measured?

Ferritin is the most sensitive single marker of iron deficiency — it falls below normal before haemoglobin, MCV, serum iron, or transferrin saturation become abnormal, allowing detection of depleted iron stores in the pre-anaemic phase. A ferritin below 12 ng/mL confirms absent iron stores and requires no further confirmatory testing for iron deficiency. A ferritin below 30 ng/mL is highly specific for iron deficiency even in the presence of inflammatory disease. In functional medicine, a ferritin below 50–70 ng/mL — technically 'within the reference range' — is associated with symptomatic iron depletion including fatigue, hair loss, cold intolerance, restless legs, and impaired cognitive function, particularly in premenopausal women with ongoing menstrual blood loss.

Reference ranges

Standard reference

Female: 12–150 ng/mL; Male: 12–300 ng/mL # REVIEWER FLAG: Confirm Access Medical Laboratories sex-specific ferritin reference ranges — the lower limit of 12 ng/mL defines absent iron stores but is associated with symptomatic iron depletion in many patients; confirm whether Access Medical Laboratories age-stratifies ferritin ranges.

Functional medicine optimal

70–150 ng/mL (functional medicine optimal for replete iron stores with symptom resolution in premenopausal females); 100–200 ng/mL (functional optimal for males and postmenopausal females). # REVIEWER FLAG: The 70–150 ng/mL functional optimal is widely cited in integrative practice but is substantially above the mainstream haematology lower limit of normal (12 ng/mL) — reviewer to confirm appropriate framing and distinguish functional optimal from diagnostic threshold clearly.

Units

ng/mL, µg/L

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.