Iron, Serum

Fasting Required
CPT: 83540
Iron

What This Test Measures

Measures iron in bloodstream at time of draw; fluctuates throughout the day.

Preparation

Fasting required (8-12 hours)
💬 Patient Community Notes

PREP: Fast for 12 hours before the draw. The STTM community recommends stopping iron supplements for up to 5 days before testing to see true iron stores (per the Iron Institute). Draw in the morning — serum iron has diurnal variation and tends to be higher in AM. Take all iron-panel tests (serum iron, TIBC, ferritin, transferrin sat) at the same time, same conditions, for consistent interpretation. The functional medicine community targets serum iron around 110 µg/dL for women and upper 130s for men, not just 'in range.' 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

Highly variable; interpret with TIBC and ferritin for full iron picture

ICD-10 Codes

Common diagnosis codes associated with this test. Codes are assigned by your provider.

D50.9Iron deficiency anemia, unspecified
D64.9Anemia, unspecified
R53.83Other fatigue

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Lab Codes

Proprietary codes used by each lab for this test.

LabCorp
001339(order_code)
Mayo Clinic Labs
FE(order_code)
NYU Langone Health
LAB829(order_code)
Quest Diagnostics
571(order_code)
Stanford Health Care
TRFS(order_code)

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Related Tests

UIBC (Unsaturated Iron Binding Capacity)

CPT: 83550

Ferritin

CPT: 82728

TIBC (Total Iron Binding Capacity)

CPT: 83550

Iron & TIBC Panel

CPT: 83540, 83550

Soluble Transferrin Receptor (sTfR)

CPT: 84466

Iron and TIBC Panel

CPT: 83540, 83550

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.