Transferrin Saturation
Fasting RequiredWhat This Test Measures
Calculated value: serum iron divided by TIBC x 100; percentage of transferrin bound to iron.
Preparation
PREP: Fast 12 hours and stop iron supplements for up to 5 days before testing. Transferrin saturation has diurnal variation — draw in the morning for consistent results. The functional medicine community targets ~35% for women and ~38% or higher for men. If serum iron, % saturation, AND ferritin are all elevated, the STTM community recommends testing for hereditary hemochromatosis. Always interpret as part of a full iron panel (serum iron, TIBC, ferritin), not in isolation. 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
<16% suggests iron deficiency; >45% suggests hemochromatosis
ICD-10 Codes
Common diagnosis codes associated with this test. Codes are assigned by your provider.
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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.