Definition
What UIBC measures
Unsaturated iron-binding capacity is the leftover transferrin that is not currently carrying iron. TIBC is roughly UIBC plus serum iron.
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Nutrient statusEssentialCompleteug/dL
UIBC
The unused portion of iron-binding capacity
Illustrative sample band · Synthetic
250ug/dL
89Sample target 150–350 ug/dL391
Why it matters
How clinicians usually read it
SiPhox reports UIBC alongside TIBC and saturation so the iron panel has every piece. It moves opposite to how loaded the transport system is.
When it reads low
A lower value can mean
A lower UIBC means more of the binding sites are already filled — the pattern of iron overload or a high serum iron.
When it reads high
A higher value can mean
A higher UIBC means more empty binding sites, the usual iron-deficiency pattern. Inflammation can flatten that response.
Questions for a clinician
Bring the number into a real conversation
01
Does UIBC agree with my TIBC and saturation?
02
Could inflammation be flattening this number?
03
Which iron marker should I track next?
Educational boundary
Educational information only. Displayed ranges are illustrative sample bands, not a diagnosis, treatment plan, or substitute for the contracted laboratory report and a qualified clinician.
See it as a sample result
The sample dashboard shows an illustrative reading, target band, and trend for UIBC.