Type the transferrin from your iron panel. You see it against the adult ranges Mayo Clinic Laboratories, Labcorp and Cedars-Sinai print, the TIBC Mayo calculates from it, and — if you add the serum iron from the same report — your transferrin saturation by Mayo’s formula. Ferritin, your lab’s own range and your doctor have the last word.
250 mg/dL is
Inside all three printed ranges 250 mg/dL = 2.50 g/L
250 mg/dL: inside Mayo Clinic Laboratories’ 200–360 mg/dL for adults, inside Labcorp’s 192–364 mg/dL for women 18 to 80, inside Cedars-Sinai’s 215–380 mg/dL.
TIBC 295 mcg/dL (52.8 µmol/L) by Mayo Clinic Laboratories’ “Total iron-binding capacity (TIBC) = Transferrin x 1.18”: inside the 149–492 mcg/dL MedlinePlus prints for women, and inside Mayo’s 250–400 mcg/dL.
Labcorp: “Transferrin is responsible for 50% to 70% of the iron binding capacity of serum. Since other proteins may bind iron, transferrin is not the same as TIBC.” If your report prints its own TIBC, that measured line is the one to read — the TIBC Level Checker places it.
That is inside all three printed ranges. The range on your own lab report — and your ferritin — are what your doctor reads it against.
Mayo Clinic Laboratories: “However, serum ferritin is a much more sensitive and reliable test for demonstration of iron deficiency.” Check a ferritin result.
What moves it, in the sources’ words
- Cedars-Sinai: “Test results may vary depending on your age, sex, and health history. Your test results may also vary depending on the lab used.”
- Mayo Clinic Laboratories: “The circulating concentration increases in response to iron deficiency and decreases in response to iron overload.”
| Source | Women | Men |
|---|---|---|
| Mayo Clinic Laboratories, adults | 200–360 | 200–360 |
| Labcorp, 18 to 80 | 192–364 | 177–329 |
| Labcorp, over 80 | 149–313 | 149–313 |
| Cedars-Sinai | 215–380 | 215–380 |
This is not medical advice and it does not diagnose anything. It shows where a number sits against published ranges; what your result means for you depends on your lab, your ferritin, your other results, your history and your doctor.
Mayo Clinic Laboratories prints a normal transferrin of 200 to 360 mg/dL for adults; Labcorp prints 192 to 364 mg/dL for women and 177 to 329 mg/dL for men aged 18 to 80; Cedars-Sinai prints 215 to 380 mg/dL. A result near an edge can be inside one range and outside another. Mayo: “The circulating concentration increases in response to iron deficiency and decreases in response to iron overload.”
How to use it
Type the transferrin line from your iron panel, say whether it is printed in mg/dL or g/L, and pick the ranges for women or men and your age band. You see where it sits against each adult range a source prints, the three side by side, and what the sources say moves it. Below it is the TIBC that Mayo Clinic Laboratories calculates from a transferrin — “Total iron-binding capacity (TIBC) = Transferrin x 1.18” — placed against the TIBC ranges. If the same report prints a serum iron, type it too: you get your transferrin saturation by Mayo’s “Percent saturation = (Iron/TIBC) x 100”. It does not diagnose anything: it places a number and quotes the sources.
What transferrin is
MedlinePlus lists it among the iron tests: “Transferrin test, which measures transferrin, a protein that moves iron throughout the body”. Cedars-Sinai: “This test measures the amount of the iron transport protein transferrin in your blood.” “Your liver makes transferrin. When your body’s stores of iron run low, your liver makes more transferrin to get more iron into your blood.” Mayo Clinic Laboratories: “Transferrin is the primary plasma iron transport protein, which binds iron strongly at physiological pH.” “Transferrin concentration also depends on liver function and nutritional status.” And: “Transferrin is generally only 25% to 30% saturated with iron.”
The ranges the sources print
| Source | Women | Men |
|---|---|---|
| Mayo Clinic Laboratories, adults | 200–360 mg/dL (2.00–3.60 g/L) | 200–360 mg/dL (2.00–3.60 g/L) |
| Labcorp, 18 to 80 | 192–364 mg/dL (1.92–3.64 g/L) | 177–329 mg/dL (1.77–3.29 g/L) |
| Labcorp, over 80 | 149–313 mg/dL (1.49–3.13 g/L) | 149–313 mg/dL (1.49–3.13 g/L) |
| Cedars-Sinai | 215–380 mg/dL (2.15–3.80 g/L) | 215–380 mg/dL (2.15–3.80 g/L) |
Mayo Clinic Laboratories (test TRSF) prints one range for adults, “200-360 mg/dL”. Labcorp (test 004937) prints a table by age and sex; this checker uses its two adult bands, “18 to 80 y: Male 177−329 mg/dL, Female 192−364 mg/dL” and “>80 y: 149−313 mg/dL”, and none of its child bands. Cedars-Sinai: “The normal range for transferrin is 215 mg/dL to 380 mg/dL.” It adds: “Test results may vary depending on your age, sex, and health history. Your test results may also vary depending on the lab used.” All three print mg/dL only; the g/L figures are the same amounts divided by 100. MedlinePlus prints no transferrin range. This checker is for adults.
Transferrin and TIBC: the same carrier, two numbers
Mayo Clinic Laboratories estimates the TIBC from a transferrin: “Total iron-binding capacity (TIBC) = Transferrin x 1.18”. A transferrin of 250 mg/dL gives a TIBC of 295 mcg/dL by that formula. Labcorp adds the caution: “Transferrin is responsible for 50% to 70% of the iron binding capacity of serum. Since other proteins may bind iron, transferrin is not the same as TIBC.” So if your report prints a TIBC its lab measured, read that one — the TIBC Level Checker places it. With a serum iron, the saturation follows from Mayo’s “Percent saturation = (Iron/TIBC) x 100”. Mayo: “The degree of iron saturation is a more useful indicator of functional iron depletion or overload than transferrin concentration alone.”
What raises or lowers it
Mayo Clinic Laboratories: “The circulating concentration increases in response to iron deficiency and decreases in response to iron overload.” “An elevated transferrin may also occur in pregnancy and with the use of oral contraceptives.” “A low transferrin may also occur due to malnutrition, inflammation, liver disease, or nephrotic syndrome.” “It also acts as a negative acute phase reactant, decreasing in concentration in the presence of inflammation; however, it has a minor intraindividual biologic variation of 5%.” Labcorp: “Increased in iron deficiency anemia. It is decreased in chronic inflammatory states, hereditary atransferrinemia, some instances of acquired liver disease, neoplasia, and renal disease.” “Increased in patients on oral contraceptives and in late pregnancy. May not be elevated in iron-deficient states in which there is severe protein malnutrition (eg, kwashiorkor).” Cedars-Sinai: “Many other health conditions can cause high or low levels of transferrin.” “Aspirin, antibiotics, and birth control pills can affect your results.”
Ferritin comes first
For the question most readers here bring — is my iron low? — Mayo Clinic Laboratories says it on its transferrin page: “However, serum ferritin is a much more sensitive and reliable test for demonstration of iron deficiency.” Read transferrin beside a ferritin result, not instead of one: the Ferritin Level Checker places it against the NIH’s and the WHO’s lines.
Before the blood draw
Cedars-Sinai: “You may need to fast for a period of time, so check with your doctor for specific instructions.” Labcorp notes that transferrin “is responsible for circadian variation in serum iron (peak in AM)” — so the serum iron beside it depends on the hour, even though Mayo puts transferrin’s own day-to-day variation at 5%. Ask the person who ordered the test before changing anything you take.
Worked examples
- 250 mg/dL, woman, 18 to 80 (the page’s example): inside all three printed ranges. TIBC by Mayo’s formula: 295 mcg/dL, inside both TIBC ranges.
- 190 mg/dL, man, 18 to 80: inside Labcorp’s 177–329, under Mayo’s 200 and Cedars-Sinai’s 215 — inside 1 of the 3, and the answer says the sources disagree.
- 400 mg/dL, woman: above all three. With a serum iron of 40 mcg/dL, the TIBC is 472 mcg/dL and the saturation 40 ÷ 472 × 100 = 8.5%: under both saturation ranges.
- 2.5 g/L, woman (a lab outside the US): 250 mg/dL, inside all three. With a serum iron of 15 µmol/L, the saturation is 28.4%.
Common mistakes
- Reading transferrin as an iron level. It is the carrier, not the cargo: a high transferrin goes with LOW iron supplies in Mayo’s and Labcorp’s words.
- Confusing transferrin with transferrin saturation. Saturation is a percent; transferrin is in mg/dL or g/L. The Iron Saturation Checker places a printed saturation.
- Mixing up mg/dL and g/L. 2.5 g/L is 250 mg/dL; the checker flags a number that only makes sense in the other unit.
- Treating a calculated TIBC as a measured one. Labcorp: “transferrin is not the same as TIBC”. A TIBC your lab printed outranks the one worked out here.
- Skipping the ferritin. Mayo calls ferritin the more sensitive and reliable test for iron deficiency.
Frequently asked questions
What is a transferrin blood test?
Cedars-Sinai: “This test measures the amount of the iron transport protein transferrin in your blood.” MedlinePlus lists it among the iron tests as a test of “a protein that moves iron throughout the body”.
What is a normal transferrin level?
Mayo Clinic Laboratories prints 200 to 360 mg/dL for adults; Labcorp prints 192 to 364 mg/dL for women and 177 to 329 mg/dL for men aged 18 to 80, and 149 to 313 over 80; Cedars-Sinai prints 215 to 380 mg/dL. Your lab’s printed range is the one your doctor uses.
What does high transferrin mean?
Mayo Clinic Laboratories: “The circulating concentration increases in response to iron deficiency”. It also names pregnancy and oral contraceptives; Labcorp names late pregnancy. Ferritin is the test that settles the iron question, with your doctor.
What does low transferrin mean?
Mayo Clinic Laboratories: “A low transferrin may also occur due to malnutrition, inflammation, liver disease, or nephrotic syndrome.” It also falls with iron overload, Mayo and Labcorp say. Cedars-Sinai: “Many other health conditions can cause high or low levels of transferrin.”
How do you calculate TIBC from transferrin?
Mayo Clinic Laboratories prints it: “Total iron-binding capacity (TIBC) = Transferrin x 1.18”. A transferrin of 300 mg/dL gives 354 mcg/dL. Other labs measure the TIBC directly, and Labcorp says the two are not the same number.
Transferrin vs ferritin: what is the difference?
Transferrin carries iron through the blood; ferritin stores it. Cedars-Sinai lists ferritin among the tests ordered beside transferrin: “A test to measure ferritin, a protein that holds most of your body’s iron reserves.” Mayo Clinic Laboratories: “However, serum ferritin is a much more sensitive and reliable test for demonstration of iron deficiency.”
Is transferrin the same as transferrin saturation?
No. Transferrin is how much of the carrier protein is in your blood; saturation is the percent of its iron seats that are filled — Mayo’s “Percent saturation = (Iron/TIBC) x 100”.
The whole panel at once — every line on one screen, and whether iron + UIBC = TIBC and the saturation add up: the Iron Panel Reader. More iron and blood-count checkers: the TIBC Level Checker, the UIBC Level Checker, the Iron Saturation Checker, the Serum Iron Level Checker, the Ferritin Level Checker and the Hemoglobin Level Checker.
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This is not medical advice, and nothing here diagnoses or treats anything. It shows where a number sits against published adult ranges and quotes what the sources say moves it; your lab’s own range, your ferritin, your other results and your doctor decide what it means. Some links on this site are affiliate links: I buy what I review at full price, and a commission never changes a verdict.