What is transferrin?
Iron cannot travel loose through your blood; free iron is reactive and damages tissue. So your body has a carrier: transferrin, a protein from your liver that can grab two iron atoms at once and deliver them where they are needed, above all in the bone marrow that makes red blood cells from them. The transferrin value is the number of taxis on the road, whether they are occupied or not. How many taxis run, your liver decides on the basis of how much iron there is. If iron is scarce, the liver makes more transferrin, to pick up every atom the gut delivers straight away. If there is enough or too much, less. That makes transferrin move opposite to ferritin: in an iron deficiency the store is empty and the transferrin high. Two things cut across that pattern. With an inflammation the liver makes less transferrin, independently of the iron, and with a protein deficiency or a sick liver too. And oestrogen, from the pill or in pregnancy, makes the liver produce more transferrin without there being a deficiency. Your report shows transferrin in g/L. Normal is about 2.2 to 2.9 g/L for men and 2.5 to 3.2 g/L for women where the labs overlap. Serum iron divided by transferrin gives transferrin saturation, the share of taxis that is occupied.
Why is transferrin relevant?
Transferrin is the value that tells two kinds of anaemia apart that look alike but are treated in opposite ways. In a real iron deficiency your liver puts every taxi on the road: transferrin high, ferritin low, saturation low, and all three point the same way. In anaemia from a chronic inflammation or disease the picture is reversed: transferrin low or normal, ferritin high, and the iron sits in the store not because it has run out but because the body locks it away. In the first case iron helps; in the second iron does not help and tackling the inflammation does. Transferrin makes that distinction without further investigation. The second reason is diet. Transferrin is a protein the liver makes afresh every day, and with too little protein in the diet, on a strict diet or in a period of eating little it falls within weeks. A low transferrin without inflammation and with a normal iron is therefore one of the first signs that you take in too little protein, earlier than albumin shows it. And transferrin belongs to recognising iron overload early. In haemochromatosis transferrin is low or normal while saturation comes out far above the band, because the few taxis are all full. That pattern stands out before ferritin rises and before there is damage.
Transferrin reference ranges
What counts beside the number:
- Ferritin: high transferrin with low ferritin is a deficiency, low transferrin with high ferritin is inflammation
- Transferrin saturation, the share of taxis that is occupied
- CRP, because inflammation pushes transferrin down without anything being wrong with the iron
- Albumin and your eating pattern, because too little protein lets transferrin fall
- Whether you are pregnant or use the pill, because oestrogen lifts the value
- Your liver values with a low value without inflammation
The bands above are where the labs overlap; the upper limit in particular differs per lab. Some labs report transferrin in µmol/L instead of g/L, and that gives very different figures. More important than the band is the pattern: high transferrin with low ferritin is an iron deficiency, low transferrin with high ferritin is an inflammation. Pregnancy and the pill lift the value without a deficiency.
What Dutch labs actually use
2.5 – 3.2g/L
Between 1.8 and 2.5 and between 3.2 and 3.8 it depends on the lab, because each sets its limits on its own method and population. Above 3.8 every lab calls it abnormal.
every lab calls 2.5 – 3.2 g/L normal. Between 1.8 and 2.5 and between 3.2 and 3.8 it depends on the lab.
Every age, per lab
| Laboratory | Group | Reference range |
|---|---|---|
| Unilabs(Saltro, Medlon, SHO, Atalmedial)2026 | Men | 1.8–2.9 g/L |
| Women | 1.8–3.2 g/L | |
| Star-shl2026 | Men | 2.2–3.6 g/L |
| Women | 2.5–3.8 g/L | |
| Certe2026 | From 18 yrs | 2–3.6 g/L |
| Clinical Diagnostics2026 | Adults | 2.0–3.6 g/L |
Each band as the lab publishes it, retrieved in 2026, unless marked otherwise.
Transferrin high or low: what it means
A high transferrin means a body looking for iron. In order of how often it occurs: an iron deficiency, a pregnancy, and the contraceptive pill or other oestrogens. In an iron deficiency ferritin is low and so is saturation; in a pregnancy or on the pill transferrin is high while the store is fine, and then saturation looks lower than it is. A low transferrin means a liver making fewer taxis. In order: an inflammation or illness, a liver disease, a protein deficiency, and rarely iron overload. CRP tells it apart from inflammation, the liver values from a sick liver, and albumin and your eating pattern from a protein deficiency. A low transferrin with a saturation above 45% is the picture of overload. What you do about it: with a high transferrin from iron deficiency you refill the store with red meat, fish, legumes and green vegetables with vitamin C, and where needed an iron tablet every other day; transferrin then falls with it once the store fills. With a low transferrin from diet, protein is the lever: enough meat, fish, dairy, eggs or legumes at every meal. With a low transferrin from inflammation you do nothing about the iron. Always read transferrin beside ferritin, serum iron, transferrin saturation and CRP. Fasting is not needed, because transferrin does not swing over the day, but mention it if you are pregnant or use the pill.
What lowers it
A liver making fewer taxis, usually independently of the iron.
| Cause | How often |
|---|---|
| Inflammation or illnessWith inflammation the liver turns the production of transferrin down and that of ferritin up; the iron goes on lock, and CRP shows it | Often |
| Liver diseaseA sick liver makes less of all proteins, transferrin and albumin first | Sometimes |
| Protein deficiencyWith too little protein in the diet, a strict diet or a period of eating little, transferrin falls within weeks; an early sign | Sometimes |
| Iron overloadIn haemochromatosis there is plenty of iron and the liver makes few taxis, which are all full; saturation is then high | Rare |
What raises it
A body looking for iron, or oestrogen switching the liver on.
| Cause | How often |
|---|---|
| Iron deficiencyThe liver puts every taxi on the road to pick up the scarce iron; transferrin high, ferritin low and saturation low point the same way together | Often |
| PregnancyOestrogen makes the liver produce more transferrin and the baby asks for iron; the value rises in pregnancy, even without a deficiency | Often |
| The contraceptive pillThe oestrogen in the pill sets the liver to making more transferrin, without there being a deficiency; saturation looks lower as a result | Sometimes |
How does a transferrin blood test work?
- Referral
- Not needed. Transferrin is in the iron profile you can have measured yourself.
- Fasting
- Not needed for transferrin itself, but it is for the serum iron from the same draw, so have blood drawn in the morning, fasting.
- When
- Not during or just after an infection, because then the value is temporarily low and says nothing about your iron or your diet.
- The draw
- One tube of blood from a vein in your arm. Serum iron, ferritin and CRP come from the same draw, and saturation is calculated from it. Some labs report in µmol/L instead of g/L.
- Repeating
- Together with ferritin, three months after starting iron; transferrin falls with it once the store fills.
- Which test
- Transferrin is in the Iron & fatigue test (€99) and in .
- Where to draw
- You can draw at 250+ locations near you, no referral needed. See the locations
Frequently asked questions
What is transferrin?
The protein that carries iron through your blood, from the gut and the store to the bone marrow. Your liver makes it, and makes more of it when iron is scarce and less with inflammation, liver disease or a protein deficiency. Where ferritin is your store, transferrin is the transport, and in an iron deficiency the two move in opposite directions: the store empty, the transport high.
What is a normal transferrin level?
About 2.2 to 2.9 g/L for men and 2.5 to 3.2 g/L for women where the labs overlap; the upper limit differs per lab, and some labs report in µmol/L. More important than where you sit in the band is the combination with ferritin and transferrin saturation.
What does a high transferrin mean?
A body looking for iron. In an iron deficiency your liver puts every taxi on the road: transferrin high, ferritin low and saturation low, all three the same way. Pregnancy and the contraceptive pill lift transferrin too, through oestrogen and without a deficiency; saturation then looks lower than it is. Ferritin says which of the two it is.
What does a low transferrin mean?
A liver making fewer taxis, and that is usually independent of your iron. An inflammation or illness is the most common reason, and then ferritin is actually high and so is CRP. After that a liver disease and a deficiency of protein in the diet. Rarely it is iron overload: then there is plenty of iron, the liver makes few taxis and they are all full, with a saturation above 45%.
How does transferrin tell iron deficiency from inflammation?
By moving in opposite directions. In a real deficiency the store is empty and the transport high: ferritin low, transferrin high. In an inflammation the body locks iron away and the liver turns the transport down: ferritin high, transferrin low. The first anaemia you fix with iron, the second you do not, and with iron added you even do more harm than good in an inflammation. That is why transferrin belongs in every iron profile.
What does transferrin have to do with diet?
It is a protein your liver makes afresh every day, and without enough protein in the diet it falls within weeks. A low transferrin without inflammation and with a normal iron is therefore one of the first signs of too little protein, on a strict diet, in a period of eating little or in older age with less appetite. Enough meat, fish, dairy, eggs or legumes at every meal brings it back.
What is transferrin saturation?
Serum iron divided by transferrin: the share of taxis that is occupied right now. That number says how much iron is available for your cells, and it is the reason transferrin is measured. Low in a deficiency, high in overload, and in an inflammation low while ferritin is high.
Do I need to fast for a transferrin test?
Not for transferrin itself, because it does not swing over the day. But the serum iron from the same draw does, and without serum iron there is no saturation, so have blood drawn in the morning, fasting. Mention it if you are pregnant or use the pill, because oestrogen lifts the value.
Which tests include transferrin?
Transferrin is in the Iron & fatigue test (€99, also as an add-on for €15) and in .
Related biomarkers
Read on
Sources
- 1.Unilabs, test catalogue (Dutch): transferrin. 2026. bepalingenklapper.nl
- 2.Star-shl, test catalogue (Dutch): transferrin. 2026. star-shl.nl
- 3.Certe, test catalogue (Dutch): transferrin. 2026. bepalingenwijzer.certe.nl
- 4.Clinical Diagnostics, lab guide (Dutch): transferrin. 2026. clinicaldiagnostics.nl
- 5.LESA Laboratory diagnostics (Dutch primary-care laboratory agreement). 2026. richtlijnen.nhg.org
Educational information only, not medical advice. Consult a healthcare professional for clinical decisions.
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