TIBC Blood Test: Normal Ranges, Causes & What Your Results Mean

What Is TIBC?

Total iron-binding capacity (TIBC) measures the maximum amount of iron that transferrin — the main iron transport protein in the blood — can carry. Since transferrin is the primary vehicle for delivering iron from the gut and storage sites to the bone marrow for red blood cell production, TIBC indirectly reflects transferrin levels and the body's capacity to transport iron.

TIBC is inversely related to iron stores: when the body is iron-deficient, the liver produces more transferrin to scavenge every available iron atom, raising TIBC. Conversely, when iron stores are replete or excessive, transferrin production decreases and TIBC falls. This makes TIBC a valuable complement to serum iron and ferritin in assessing iron status.

Why Is TIBC Tested?

• Iron deficiency diagnosis — TIBC rises in iron deficiency, often before anaemia develops
• Distinguishing types of anaemia — the combination of serum iron, TIBC, ferritin, and transferrin saturation differentiates iron-deficiency from anaemia of chronic disease
• Iron overload assessment — low TIBC with high iron suggests haemochromatosis
• Monitoring iron therapy — TIBC normalises as iron stores are replenished
• Calculating transferrin saturation — TSAT = (serum iron ÷ TIBC) × 100

Normal Ranges

What Do High TIBC Levels Mean?

• Iron deficiency — the most common cause; the body upregulates transferrin to capture more iron
• Pregnancy — increased iron demands drive transferrin production higher
• Oral contraceptive use — oestrogen stimulates hepatic transferrin synthesis
• Hepatitis — acute liver inflammation can temporarily raise TIBC

What Do Low TIBC Levels Mean?

• Iron overload (haemochromatosis) — the body reduces transferrin when iron is excessive
• Anaemia of chronic disease — inflammatory conditions suppress transferrin production
• Liver disease — cirrhosis impairs hepatic transferrin synthesis
• Nephrotic syndrome — urinary loss of transferrin
• Malnutrition — protein deficiency reduces all liver-synthesised proteins
• Malignancy — cancer-related inflammation lowers TIBC

How to Interpret Your Iron Panel

How to Improve Your Iron Status

• If TIBC is high (iron-deficient) — increase dietary iron from red meat, liver, pulses, and fortified cereals; pair with vitamin C to enhance absorption
• Iron supplementation — ferrous fumarate or ferrous sulphate as prescribed by your GP
• Identify the cause — heavy periods, GI blood loss, coeliac disease, or dietary inadequacy must be addressed
• If TIBC is low (iron overload) — refer for haemochromatosis gene testing (HFE C282Y/H63D); treatment is therapeutic venesection
• Retest after 3 months — iron parameters take weeks to normalise with supplementation

When Should You Get Tested?

• Symptoms of iron deficiency: fatigue, pallor, breathlessness, restless legs, hair loss
• Unexplained anaemia — to distinguish iron deficiency from other causes
• Family history of haemochromatosis
• Monitoring response to iron supplementation
• As part of a comprehensive iron panel

Which Lola Health Tests Include TIBC?

TIBC is available as an add-on biomarker and is included in the iron panel alongside serum iron, ferritin, and transferrin saturation in Vital Check and Peak Insights.