What does the Ferritin, Serum test measure?

Why is Ferritin, Serum measured?

Ferritin is the most sensitive and specific single serum marker for iron deficiency — falling below normal before haemoglobin, MCV, serum iron, or transferrin saturation become abnormal, enabling detection of depleted iron stores in the pre-anaemic phase when intervention is most effective and least disruptive. A ferritin below 12–15 ng/mL confirms absent iron stores with near-certainty and requires no additional iron status confirmation. Conversely, ferritin is an indispensable marker for iron overload assessment — elevated ferritin with high transferrin saturation triggers HFE gene mutation testing for hereditary haemochromatosis. In functional and integrative medicine, ferritin carries significant clinical actionability at concentrations well above the reference range lower limit — values in the 12–50 ng/mL range that are technically 'within normal' but functionally insufficient for optimal cellular iron-dependent processes (erythropoiesis, thyroid hormone synthesis, mitochondrial function, neurotransmitter production, hair follicle cycling) are a primary clinical focus in fatigue and symptom assessment, particularly in premenopausal women. The dual identity of ferritin as both an iron status marker and an acute phase reactant requires concurrent inflammatory marker assessment for accurate iron status interpretation in patients with chronic disease.

Reference ranges

Standard reference

Female (18–39): 10–154 ng/mL; Female (≥40): 13–150 ng/mL; Male (18+): 22–322 ng/mL # REVIEWER FLAG: Confirm LabCorp sex-specific and age-stratified ferritin reference ranges — LabCorp applies age-banded female ranges and a broader male range reflecting higher physiological iron stores in males; confirm exact age bands and lower/upper limits from LabCorp's current assay documentation. Confirm assay methodology — most platforms use electrochemiluminescence immunoassay (ECLIA) or chemiluminescent microparticle immunoassay (CMIA); confirm which LabCorp uses, as methodology affects calibration and may produce slightly different absolute values from other platforms.

Functional medicine optimal

Functional medicine optimal: 70–150 ng/mL (females); 100–200 ng/mL (males) — reflecting replete iron stores with full cellular iron-dependent enzyme saturation and symptom resolution in most patients. Many integrative practitioners target a minimum of 50 ng/mL for women with fatigue, hair loss, or thyroid-related symptoms, and above 70 ng/mL for optimal erythropoietic support and hair follicle cycling. # REVIEWER FLAG: The 70–150 ng/mL functional optimal for females substantially exceeds the mainstream lower limit of normal (10–12 ng/mL) and is not endorsed as a supplementation target in mainstream haematology guidelines — reviewer to confirm appropriate framing distinguishing the functional optimal from the diagnostic deficiency threshold, and whether the hair loss and fatigue associations for low-normal ferritin should be cited with specific evidence references.

Units

ng/mL, µg/L

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