Total Iron Binding Capacity
TIBC· also: Total Iron Binding Capacity
Clinical Overview
TIBC measures the maximum amount of iron that blood can carry — it reflects the total amount of transferrin available to bind iron. Transferrin is produced by the liver and is the transport protein for iron. In iron deficiency, the liver produces more transferrin (high TIBC); in iron overload or chronic disease, the liver produces less (low TIBC).
Why This Test Matters
TIBC is an indirect measure of transferrin and helps interpret serum iron. In iron deficiency: TIBC is high (liver compensates by making more transferrin), serum iron is low, ferritin is low, and transferrin saturation is low. In anemia of chronic disease: TIBC is low or normal (liver makes less transferrin during inflammation), serum iron is low, but ferritin is normal or high — distinguishing it from iron deficiency.
Reference RangesWHO/IFCC standards
| Reference Range | Unit | Notes |
|---|---|---|
| 250 – 370 | µg/dL | — |
Also reported in: µmol/L.
What Causes Abnormal Results?
High TIBC Causes
- Iron deficiency anemia (most common)
- Pregnancy (increased transferrin production)
- Oral contraceptive use (estrogen stimulates transferrin synthesis)
Low TIBC Causes
- Anemia of chronic disease (liver reduces transferrin production)
- Iron overload / hemochromatosis (transferrin is saturated)
- Liver disease (reduced transferrin synthesis)
- Nephrotic syndrome (transferrin lost in urine)
- Malnutrition
Signs & Symptoms to Watch For
How to Prepare for This Test
No special preparation. Best drawn in the morning alongside serum iron and ferritin for a complete iron panel.
Factors That Can Affect Results
- Hemolysis (falsely lowers TIBC)
- Recent iron infusion (TIBC may temporarily shift)
Related Topics
Frequently Asked Questions
What is the UIBC and how is it different from TIBC?
UIBC (unsaturated iron-binding capacity) measures the portion of transferrin that is not yet bound to iron — the reserve capacity. TIBC = serum iron + UIBC. TIBC can be measured directly or calculated from UIBC. Both tests reflect transferrin levels; TIBC is more commonly reported. The key clinical value is calculating transferrin saturation from serum iron and TIBC.