Type the transferrin saturation from your iron panel — “% saturation”, “Iron saturation” or “TSAT” — or work it out from the serum iron and TIBC on the same report. You see it against the lines MedlinePlus, Mayo Clinic Laboratories and Cleveland Clinic draw, and what each says at that line. Ferritin, your lab’s own range and your doctor have the last word.
28% is
Inside all three ranges as printed: 28%
Transferrin saturation 28%: inside the 15–45% MedlinePlus prints for women, inside the 14–50% Mayo Clinic Laboratories prints for adults, and inside the 20–50% Cleveland Clinic calls normal.
- Mayo Clinic Laboratories: “Transferrin is generally only 25% to 30% saturated with iron.”
That is inside all three 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
- Mayo Clinic Laboratories: “Iron concentration and percent saturation decrease with iron deficiency and increase when iron is in excess.”
- Mayo Clinic Laboratories: “The intraindividual day-to-day variation of iron and iron saturation is approximately 25% to 30%.”
- Cleveland Clinic: “But one result outside the normal range doesn’t necessarily mean you have a health problem.”
| Source | Women | Men |
|---|---|---|
| MedlinePlus | 15–45% | 20–50% |
| Mayo Clinic Laboratories | 14–50% | 14–50% |
| Cleveland Clinic | 20–50% | 20–50% |
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.
Normal iron saturation is about 15% to 45% for women and 20% to 50% for men, and some labs use 14% to 50% for all adults. Under 16%, or under 20% where there is inflammation, is used to screen for iron deficiency. Over 45% is where hereditary hemochromatosis often sits.
How to use it
If your iron panel prints a saturation (“% saturation”, “Iron saturation”, “Transferrin saturation” or “TSAT”), type it and pick the ranges for women or men. If it does not, switch to “Iron and TIBC” and type both from the same report, in the same unit. The checker then works the % out for you. It shows where your % sits against all three sets of lines, one above the other, and what it means where it crosses one. It does not diagnose anything.
What the saturation is
Transferrin saturation (TSAT) is a blood test that shows the percentage of transferrin that’s carrying iron. Transferrin is the protein that carries iron in the blood. The TIBC is all of its iron seats, and the saturation is the share that are filled, generally only 25% to 30%. The lab works it out as (Iron / TIBC) x 100. A serum iron of 75 and a TIBC of 300 make 25%.
The normal ranges
| Source | Women | Men |
|---|---|---|
| MedlinePlus | 15–45% | 20–50% |
| Mayo Clinic Laboratories | 14–50% | 14–50% |
| Cleveland Clinic | 20–50% | 20–50% |
The ranges don’t all match, and some labs differ slightly. So 17% is inside two lines and under the third, and 48% for a woman is above one line and inside the other two. Most labs print their own reference range, and your report’s range is the one that applies.
What each line means
- Under 20%: a saturation under 16% is generally used to screen for iron deficiency, with a threshold of 20% when inflammation is present. Levels below 20% may mean iron deficiency anemia, malabsorption or chronic inflammation, and in iron deficiency anemia the saturation is under 15% with a raised TIBC.
- Over 45%: saturation often exceeds 45% in hereditary hemochromatosis and 90% in advanced iron overload states.
- Over 50%: levels typically mean iron overload (hemochromatosis) or a liver condition.
Iron and saturation both fall with iron deficiency and rise when iron is in excess, but one result outside the normal range doesn’t necessarily mean a health problem.
Ferritin comes first
If your question is “is my iron low?”, serum ferritin is a much more sensitive and reliable test for iron deficiency, so read the saturation beside a ferritin result, not instead of one. The Ferritin Level Checker places a ferritin result, and the Serum Iron Level Checker and the TIBC Level Checker read the two lines the % is made from.
Before the blood draw
You typically don’t need to prepare, but your provider may ask you to avoid eating or drinking the morning of the test. Serum iron moves through the day, and iron and saturation vary about 25% to 30% from day to day. Some labs want 24 hours without iron-containing supplements, so ask the person who ordered the test before changing anything you take.
Worked examples
- 28%, woman: inside all three lines, and near the usual 25% to 30%.
- 17%, woman: inside 15–45% and 14–50%, and under the 20% line used when inflammation is present.
- 17%, man: under the 20% line for men and inside 14–50%.
- Iron 60 and TIBC 450: 60 ÷ 450 × 100 = 13.3%, under all three lines and under the 16% screening line.
- 62%, man: above all three lines, past both the 45% and the 50% points.
Common mistakes
- Reading the saturation as an amount of iron. It is a share. A low iron with a low TIBC can give an ordinary-looking %. Ferritin is the stores test.
- Mixing units in the formula. The iron and the TIBC must be in the same unit. The % itself has no unit.
- Typing a fraction. A report that prints 0.25 means 25%.
- One line taken as the line. The lines differ by up to 6 points at the bottom, and your lab prints its own.
- Taking iron before the test. Some labs ask for 24 hours without iron-containing supplements.
Frequently asked questions
What does low iron saturation mean?
A saturation under 16% (under 20% with inflammation) is used to screen for iron deficiency, and levels below 20% may mean iron deficiency anemia, malabsorption or chronic inflammation. Ferritin is the test that settles it, with your doctor.
What does high transferrin saturation mean?
Saturation often exceeds 45% in hereditary hemochromatosis and 90% in advanced iron overload states, and levels over 50% typically mean iron overload (hemochromatosis) or a liver condition. One result outside the range does not necessarily mean a health problem.
What is a normal transferrin saturation?
Common ranges are 15% to 45% for women and 20% to 50% for men, or 14% to 50% for adults at some labs. Your lab’s printed range is the one your doctor uses.
How is transferrin saturation calculated?
Serum iron divided by TIBC, times 100. Both numbers must be in the same unit.
Is iron saturation the same as TSAT?
Yes. Labs print it as “% saturation”, “Iron saturation”, “Transferrin saturation”, “TSAT” or “Transferrin iron saturation”.
Is a 17% iron saturation low?
It depends on the range. It’s inside 15–45% for women and 14–50%, but under the 20% line for men and under the general 20% line. The screening line is 16%, or 20% where there is inflammation.
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 Transferrin Level Checker, the UIBC Level Checker, the Hemoglobin Level Checker and the Iron Tablet Timing Planner.
Sources
- MedlinePlus: Iron Tests
- Mayo Clinic Laboratories: Iron and Total Iron-Binding Capacity, Serum
- CDC: NHANES laboratory manual for iron and total iron-binding capacity
- Cleveland Clinic: Transferrin Saturation
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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 lines and what they mean. 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.