Ferritin — Normal Range & Interpretation

Clinical Context

Ferritin reflects total body iron stores and serves as the single most sensitive and specific test for iron deficiency anemia. Each nanogram per milliliter of serum ferritin correlates with roughly 8 mg of stored iron, making it the first-line lab when evaluating microcytic anemia, fatigue, restless legs syndrome, or unexplained hair loss.

Low ferritin always indicates true iron deficiency and points the NP toward occult gastrointestinal bleeding, heavy menstrual bleeding, pregnancy, malabsorption from celiac disease or bariatric surgery, or inadequate dietary intake. Elevated ferritin signals iron overload states like hereditary hemochromatosis, but as an acute phase reactant it also rises with infection, chronic inflammation, malignancy, liver disease, and metabolic syndrome. This dual behavior masks iron deficiency in patients with concurrent inflammation, so the NP orders a CRP or transferrin saturation to clarify ambiguous results.

FNPs see ferritin on the boards most often as the best initial test for suspected iron deficiency, differentiate iron deficiency anemia from anemia of chronic disease, and identify hemochromatosis when ferritin and transferrin saturation are both elevated. Expect questions linking low ferritin to menorrhagia in reproductive-age women and to colon cancer screening in older adults with unexplained microcytic anemia.

Related Labs

• HbA1c — %
• ESR — mm/hr
• CRP — mg/dL
• hs-CRP — mg/L
• Uric Acid — mg/dL

Sources

• MedlinePlus
• ARUP Consult