What does the Ferritin test measure?

Why is Ferritin measured?

Ferritin is the most sensitive and specific single marker for iron deficiency — falling below normal before haemoglobin, MCV, or serum iron become abnormal, allowing detection of pre-anaemic iron depletion. In premenopausal women with recurrent menstrual blood loss, ferritin is the primary iron status marker for monitoring. Functional medicine practitioners apply substantially higher optimal ferritin targets than the laboratory lower limit — low-normal ferritin in the context of fatigue, hair loss, cold intolerance, or restless legs warrants clinical attention despite being within the reference range.

Reference ranges

Standard reference

Adult men ~30–400 ng/mL; adult women ~15–150 ng/mL; thresholds for deficiency vary # REVIEWER FLAG: Lower limits and deficiency cut-offs differ by guideline and assay (e.g. <30 ng/mL widely used for deficiency, <15 ng/mL more specific) — reviewer to confirm Quest assay-specific ranges before publication.

Functional medicine optimal

70–150 ng/mL (functional medicine optimal; levels below 50 ng/mL are associated with symptomatic iron depletion including fatigue, hair loss, and impaired thermoregulation in many functional medicine frameworks even in the absence of anaemia). # REVIEWER FLAG: The 70–150 ng/mL optimal is not standardised in mainstream haematology guidelines — reviewer to confirm appropriate framing for this platform.

Units

ng/mL, µg/L

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