Quick answer: the TIBC normal range on MedlinePlus is 171 to 505 mcg/dL (30.6 to 90.3 µmol/L) for men and 149 to 492 mcg/dL (26.7 to 88.0 µmol/L) for women. Normal iron (transferrin) saturation is 20% to 50% for men and 15% to 45% for women. UIBC, the unsaturated binding capacity, is TIBC minus serum iron. A high TIBC with a low saturation suggests iron deficiency; a saturation of 45% or more is the ACG's trigger to test for hereditary hemochromatosis.
TIBC, UIBC and iron saturation ranges
MedlinePlus Medical Encyclopedia, TIBC test. The ACG hemochromatosis guideline uses 45% or more as the level that should prompt HFE gene testing.
| Test | Men | Women | Source |
|---|---|---|---|
| Serum iron | 59 to 158 mcg/dL (10.6 to 28.3 µmol/L) | 37 to 145 mcg/dL (6.6 to 25.9 µmol/L) | MedlinePlus |
| TIBC | 171 to 505 mcg/dL (30.6 to 90.3 µmol/L) | 149 to 492 mcg/dL (26.7 to 88.0 µmol/L) | MedlinePlus |
| Iron saturation | 20% to 50% | 15% to 45% | MedlinePlus |
| UIBC | TIBC minus iron | TIBC minus iron | Calculation |
To convert mcg/dL to µmol/L, multiply by 0.179 (the pairs above follow this). Ranges vary by lab.
What these tests measure
Iron travels in the blood bound to a carrier protein, transferrin. TIBC (total iron-binding capacity) measures how much iron transferrin could carry if every seat were full, so it is effectively a transferrin measure. Serum iron is how much is actually on board. UIBC (unsaturated iron-binding capacity) is the empty seats. Iron saturation, also called transferrin saturation or TSAT, is the percentage of seats taken.
When the body is short of iron, the liver makes more transferrin, so TIBC and UIBC rise and saturation falls. When iron is in excess, saturation climbs. Ferritin, the storage protein, completes the picture. Serum iron varies through the day and may be higher in the morning, so MedlinePlus says your provider may ask for a 12-hour fast and a morning draw.
How the numbers connect
- Iron saturation (%) = serum iron / TIBC x 100
- UIBC = TIBC minus serum iron
- TIBC = serum iron + UIBC
If your report shows iron 100 mcg/dL and TIBC 330 mcg/dL, saturation is 100 / 330 = 30% and UIBC is 230 mcg/dL.
What the patterns mean
| Pattern | Most likely meaning | Source |
|---|---|---|
| High TIBC, low saturation, low ferritin | Iron deficiency; also late pregnancy raises TIBC | MedlinePlus |
| Low TIBC, low iron, normal or high ferritin | Inflammation or chronic disease, liver disease, malnutrition or low protein | MedlinePlus |
| Saturation 45% or more | Possible iron overload; HFE gene testing is indicated if unexplained | ACG 2019 |
| Low TIBC with hemolysis | Red cells destroyed too fast (hemolytic anemia) | MedlinePlus |
The ACG guideline adds that a high ferritin alone, without a raised saturation, should not be used as a reason for HFE testing. Saturation is the better first screen.
Worked examples
Iron deficiency: a 29-year-old woman has iron 40 mcg/dL and TIBC 450 mcg/dL. Saturation is 40 / 450 = 8.9%, well under the female floor of 15%. UIBC is 410 mcg/dL. With a ferritin of 8 ng/mL, iron deficiency is clear, and her doctor will look for the cause.
Possible overload: a 44-year-old man has iron 190 mcg/dL and TIBC 280 mcg/dL. Saturation is 190 / 280 = 68%, above both the 50% range limit and the ACG's 45% trigger. A fasting repeat and a doctor's review for hemochromatosis testing come next.
Inflammation: iron 50 mcg/dL, TIBC 220 mcg/dL (saturation 23%) and ferritin 350 ng/mL. The low iron here reflects inflammation, not a shortage, so iron pills would not be the answer.
Which test to use
| If you want | Test | Where |
|---|---|---|
| Just an iron-stores check | Ferritin | SiPhox Longevity Essentials or Thyroid Focus |
| The full iron panel | Iron, TIBC, UIBC, saturation and ferritin | SiPhox Ultimate 360 or GLP Optimization |
| Iron panel plus B12, folate and hemoglobin for anemia | Full iron panel, B12, folate, hemoglobin | SiPhox Ultimate 360 |
| HFE gene testing | Genetic test | Your doctor |
How to prepare for iron tests
- Morning, fasting. MedlinePlus says iron varies through the day and may be higher in the morning, and your provider may ask for a 12-hour fast with a morning draw.
- Note hormones and your cycle. Birth control pills and estrogen treatment can affect iron levels, and iron may be lower during menstruation (MedlinePlus).
- Read saturation with ferritin. The ACG uses a raised saturation, not ferritin alone, as the trigger for hemochromatosis testing, and a fasting repeat helps confirm a high saturation.
- Retest after treatment. If you start iron for deficiency, a repeat panel after a few months shows whether saturation and ferritin are recovering.
At-home tests with TIBC
TIBC, UIBC and iron saturation are on two SiPhox panels: Ultimate 360 and GLP Optimization. Both also include serum iron and ferritin. No other SiPhox panel has TIBC, though ferritin alone is on Longevity Essentials and Thyroid Focus.
| SiPhox panel | Biomarkers per test | Per test, with shipping | Listed as |
|---|---|---|---|
| Ultimate 360 | 62 | $274 | TIBC (Nutrition) |
| GLP Optimization | 46 | $224 | TIBC (Nutrition) |
For a morning, fasted sample, collect before breakfast, since iron varies through the day. SiPhox is a wellness service with no doctor review included, so bring a saturation of 45% or more, or clear iron deficiency, to your doctor. Compare options in our at-home iron test guide and our low ferritin symptoms guide.
A note on home samples: SiPhox's partner lab tests capillary blood collected from the upper arm. SiPhox says its results show a 95% to 99% correlation with venous draws in its own quarterly comparisons against Labcorp and Quest, but it has not published a study of the EasyDraw device. If a result would change a treatment decision, confirm it with a venous test through your doctor.
Ultimate 360
Everything on the four core panels plus iron studies, B12 and folate, GGT and PSA.
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GLP Optimization
Built for people on GLP-1 medication: metabolic, liver, kidney, nutrient and iron markers.
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Frequently asked questions
What is a normal TIBC?
171 to 505 mcg/dL for men and 149 to 492 mcg/dL for women, according to MedlinePlus. Labs vary.
What is a normal iron saturation?
20% to 50% for men and 15% to 45% for women (MedlinePlus). The ACG uses 45% or more as the trigger to consider hemochromatosis testing.
What is UIBC?
Unsaturated iron-binding capacity: the part of transferrin not carrying iron. UIBC equals TIBC minus serum iron.
What does a high TIBC mean?
Usually that the body is short of iron and is making more transferrin. Late pregnancy also raises TIBC.
Can I test TIBC at home?
Yes. SiPhox Ultimate 360 and GLP Optimization include iron, TIBC, UIBC, iron saturation and ferritin.
Sources
- MedlinePlus Medical Encyclopedia: Total iron binding capacity
- MedlinePlus Medical Encyclopedia: Serum iron test
- MedlinePlus Lab Tests: Iron tests
- Kowdley KV et al. ACG clinical guideline: hereditary hemochromatosis. Am J Gastroenterol 2019
- SiPhox Health: panel comparison (checked 29 Sep 2026)
- SiPhox Health: Ultimate 360 panel
- SiPhox Health: GLP Optimization panel