TIBC optimal range and reference range

Compiled by Alina Radu, founder of Sera, from the published sources below · Last reviewed November 9, 2026

Sera's bands for TIBC:

Optimal 275 – 350 μg/dL (49.3 – 62.7 μmol/L); sufficient 250 – 400 μg/dL (44.8 – 71.6 μmol/L); out of range below 250 or above 400 μg/dL.

Evidence grade: Published reference interval. A band that primarily reflects a published adult laboratory or population reference interval. It is not necessarily applicable to every assay or laboratory.

At Sera's last range review a change to this band was proposed and held, because the evidence for it was thin, so the band is unchanged. The note below says where it matches published intervals and where it does not.

All units

Unit	Optimal	Sufficient	Out of range
μg/dL	275 – 350	250 – 400	below 250 or above 400
μmol/L	49.3 – 62.7	44.8 – 71.6	below 44.8 or above 71.6
mg/dL	0.275 – 0.35	0.25 – 0.4	below 0.25 or above 0.4

What the evidence says

Laboratories agree on a lower limit near 240 to 250 μg/dL and differ at the top: ARUP reports 240 to 450, and the interval commonly used by US laboratories is 250 to 450. Sera's upper edge of 400 follows the narrower interval some laboratories print. The optimal band of 275 to 350 is a functional target with no published source.

Sources

Iron and Iron Binding Capacity | ARUP Laboratories Test Directory — ARUP Laboratories, 2026 · Laboratory / reference-interval sourceAdult (18 years and older) TIBC reference interval of 240 to 450 µg/dL. Supports a lower edge of about 250 and an upper edge of 450 rather than Sera's 400.
Population Heterogeneity in Iron Biomarkers by Age, Sex, Menopausal Status, and Race in Healthy U.S. Adults: A Cross-Sectional Analysis from the All of Us Research Program — Zeidan RS, Yang JJ, He R, et al. — Nutrients, 2026 · Peer-reviewed publicationLists the reference intervals commonly used by US clinical laboratories, according to the National Board of Medical Examiners: TIBC 250 to 450 µg/dL (240 to 450 in postmenopausal women). Matches Sera's lower edge of 250; the upper edge is 450, not 400.

What TIBC (Total Iron Binding Capacity) measures

A measure of how much iron your blood is able to carry on transferrin.

High TIBC points to iron deficiency. Helps tell different types of anemia apart.

Related blood cell health markers

See TIBC in the full list of biomarker ranges

This page is a reference for practitioners, not medical advice. Sera's bands are practitioner targets for structured review, not diagnostic thresholds, and Sera does not diagnose or recommend treatment. Read a result alongside the interval printed by the issuing laboratory and the client's history and symptoms. Range set: Sera Production, version 1.0, last reviewed November 9, 2026.