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Transferrin Saturation

Transferrin saturation: iron transport, iron stores and hereditary iron overload

According to the NVKC, the body absorbs iron in the gut, binds it directly to the transport protein transferrin and keeps a reserve in the cells of the liver, in the protein ferritin. Transferrin saturation gives the percentage of transferrin that is saturated with iron.

According to Thuisarts, in hereditary iron overload the body takes too much iron from food and drink, and ever more iron can damage organs such as the liver and the heart. According to the NHG, in iron-deficiency anaemia the saturation is lowered instead. Only a blood test shows whether transferrin saturation is abnormal.

Unilabs gives 0.12 to 0.43 for men, without a unit, and Diagnostiek voor U uses 20 to 45% for men.

Doctor's Assessment Included

Transferrin saturation shows what percentage of the iron transport protein transferrin is saturated with iron. According to the NVKC, the saturation usually lies between 20% and 45%, and it helps establish whether there is iron deficiency or iron overload.

Diagnostiek voor U uses 15 to 45% in women and 20 to 45% in men; Unilabs gives 0.06 to 0.43 in women and 0.12 to 0.43 in men, without a unit.
According to the NVKC, in iron-deficiency anaemia transferrin saturation is often below 10%.
According to the NVKC, a transferrin saturation above 50%, with iron (much) higher than 20 µmol/l, can point to iron overload.

Reference Ranges

Male

Low 20 Normal 45 High

Source: NVKC Reference population: Dutch adults (NVKC)

Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.

Check your own value

Transferrin Saturation: what Dutch laboratories use

Reference ranges by group, in %
Laboratory	Group	Reference value (%)	Relative scale
Diagnostiek voor U	· Male	20–45 %	20 45

0 49.5 %

Source: Diagnostiek voor U

Each value as the laboratory itself publishes it, retrieved in 2026.

Transferrin Saturation: what this test measures

Transferrin saturation expresses as a percentage how much of the transferrin is saturated with iron, and according to the NVKC it is calculated from the amount of iron in serum and the transferrin concentration. Unilabs uses the formula (iron × 0.5) divided by (transferrin × 12.6), with iron in µmol/l and transferrin in g/l, and gives the outcome without a unit.

Transferrin Saturation: why this value matters

According to the NVKC, in people with symptoms of iron overload ferritin is often above 500 micrograms/l with a transferrin saturation well above 50%, and ferritin then maps the severity of the overload. According to Erfelijkheid.nl, the Dutch genetics information site, primary haemochromatosis, the hereditary form, occurs in about 1 in 400 people of Northern European descent.

Transferrin Saturation: how the blood test works

Referral: No GP referral needed. After the order we arrange the referral through ZorgDomein, within one business day; orders after 17:00 or at the weekend start on the next business day. ZorgDomein emails a barcode, and that barcode is what the draw site needs.
The draw: A blood draw from a vein in the arm, at a partner laboratory's draw site. No home kit, no finger prick.
Which test: Iron Studies · €89,- · Anemia · €132,-
Where: 650+ draw sites run by independent laboratories across the Netherlands. Draw sites

Transferrin Saturation: how to prepare

Preferably fasting
Recommended

Coming fasting gives a slightly cleaner value, but it is not required. If it suits you, eat nothing from 22:00 the evening before and drink only water.
Preferably in the morning
Recommended

A morning draw makes this value easiest to compare with its reference range. Plan the draw before 10:00 if you can.

Water is always fine. Drink as usual beforehand, it makes the draw easier.
Take your usual medication, unless your own doctor told you otherwise.

Transferrin Saturation: when is testing worthwhile?

According to the NVKC, with suspected iron overload, or when the condition runs in the family, transferrin is often requested together with iron and ferritin, and transferrin saturation follows from iron and transferrin. According to Thuisarts, parents, and brothers, sisters and children from age 18, can be tested when someone in the family has hereditary iron overload.

Transferrin Saturation: symptoms of a high or low value

Low Levels

According to the NHG, a lowered transferrin saturation fits iron-deficiency anaemia, because iron is then lowered and the iron-binding capacity raised. According to Thuisarts, losing small amounts of blood through the stomach or gut over a longer period is often the cause of anaemia in people over 50.

High Levels

According to the NVKC, in a raised result iron is (much) higher than 20 µmol/l and transferrin saturation above 50%, and iron overload may then be present. According to Thuisarts, people with hereditary iron overload often notice little or nothing of it, and symptoms may only become noticeable once there is a lot of iron in the body, usually between the ages of 40 and 50. According to Thuisarts, in hereditary iron overload heart problems usually only arise when there is far too much iron in the body.

Transferrin Saturation: causes of a low or high value

What lowers the value

Iron deficiency from blood loss

Chronic blood loss can lead to iron deficiency, and women can lose too much blood during menstruation; in the iron-deficiency anaemia that can result, transferrin saturation is often below 10%.
Iron deficiency from diet or gut function

A poor diet or poor gut function can lead to iron deficiency, and transferrin saturation helps establish that deficiency.

What raises the value

Iron overload (haemochromatosis)

With iron (much) higher than 20 µmol/l and a transferrin saturation above 50%, there may be iron overload, in which the body constantly absorbs too much iron from food in the gut.
Having just started iron tablets

A raised result for iron and transferrin saturation can also occur in people who have just started taking iron tablets.

Transferrin Saturation: lifestyle and this value

Take a transferrin saturation that is out of range to your GP. According to Thuisarts, hereditary iron overload is usually treated with bloodletting, at first for example once every 1 or 2 weeks and after that usually 4 to 8 times a year.

Transferrin Saturation: frequently asked questions

Is iron overload always hereditary?

No, iron overload, in which transferrin saturation can be above 50% according to the NVKC, is not always hereditary. According to Erfelijkheid.nl, primary haemochromatosis is hereditary and secondary haemochromatosis is not; someone can get the latter, for example, after many blood transfusions or from some diseases of the blood and the liver.

Transferrin Saturation: sources

Nederlandse Vereniging voor Klinische Chemie en Laboratoriumgeneeskunde. Alles over testen. Over AFP: "De referentiewaarden kunnen verschillen tussen laboratoria, afhankelijk van de methode. Ga daarom uitsluitend af op de referentiewaarden van het laboratorium dat het onderzoek heeft uitgevoerd en interpreteer nooit AFP-uitslagen van verschillende laboratoria door elkaar." Geraadpleegd 14 juli 2026. (retrieved 2026) allesovertesten.nl
Diagnostiek voor U, eLabgids (Referentiewaarden DvU), diagnostiek.getincontrol.eu, geraadpleegd 2026-10-01 (retrieved 2026) diagnostiek.getincontrol.eu
NVKC, Alles over testen: IJzer, allesovertesten.nl, geraadpleegd 2026-10-16 (retrieved 2026) allesovertesten.nl