Ferritin
What This Test Measures
Iron storage protein; the most sensitive single test for iron deficiency (low) and iron overload (high). Also an acute-phase reactant — ferritin rises with inflammation, infection, or illness, which can mask true iron deficiency. Always interpret alongside CRP or hs-CRP. Extremely high levels (500+) may indicate active inflammatory disease; levels above 10,000 can be seen in serious conditions like hemophagocytic lymphohistiocytosis (HLH), Still's disease, or severe sepsis.
Preparation
PREP: The STTM/iron community recommends stopping iron supplements for up to 5 days before testing to see what your body is truly 'holding onto' (per the Iron Institute). Fasting is recommended (at least 12 hours). IMPORTANT: Ferritin is an acute phase reactant — it rises with inflammation, infection, or illness, masking true iron deficiency. If ferritin is elevated, check CRP alongside it. Standard ranges (e.g., 10–232 ng/mL) set a very low floor. The functional medicine community considers optimal ferritin 50–150 ng/mL, with 70–100 ng/mL as the sweet spot for energy, hair, and thyroid conversion. A ferritin of 20 is technically 'in range' but functionally deficient. These notes reflect common practices in thyroid/functional medicine communities.
Reflects common practices in thyroid, BHRT, and functional medicine communities. This may differ from standard clinical guidelines. Not medical advice — always discuss with your provider.
General guidelines only. Requirements vary by lab and individual. Confirm with your provider before adjusting any medications.
Turnaround Time
Varies by lab
Clinical Notes
Can be falsely elevated as acute phase reactant in inflammation; interpret with CRP
ICD-10 Codes
Common diagnosis codes associated with this test. Codes are assigned by your provider.
Self-Pay Pricing
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Uses LabCorp draw centers · Not available in NY, NJ, RI, HI, ND, or VT · Membership may be required
Uses Quest Diagnostics network; generally lowest DTC prices; not available in NY, NJ, RI
Uses Labcorp network; known for supplement company; competitive lab test pricing
Uses both Quest and Labcorp networks; competitive pricing; broad test selection
Uses Quest Diagnostics network; good panel pricing; established DTC provider
Uses Quest and Labcorp; strong panel bundling; results in 1-3 days
Uses Quest and Labcorp networks; offers both individual tests and discounted panels
Uses Quest and Labcorp; no hidden draw or facility fees; moderate pricing
Labcorp consumer-direct platform; 2,000+ locations; results in 1-3 days
Quest Diagnostics consumer-direct platform; results in 1-2 days; 2,100+ locations nationwide
Primarily uses Labcorp network; popular for hormone panels; higher individual test prices
Lab Codes
Proprietary codes used by each lab for this test.
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For informational purposes only
This page is for educational and research purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. ICD-10 and CPT codes are assigned by your healthcare provider. Always consult a qualified healthcare provider before ordering any lab test or making decisions about your health.