Iron blood test: normal range and what the result means (Fe)

Iron is needed for haemoglobin — the protein that carries oxygen — and for many enzymes. In the blood it is carried by a protein called transferrin, and stores are held in ferritin. A serum iron test measures only the iron transferrin is carrying at that moment: the result changes through the day (it is higher in the morning), after eating, during an infection, and when supplements are taken. That is why iron on its own is often misleading — the whole iron profile is assessed: iron, ferritin (the stores), TIBC (how much iron transferrin could bind) and transferrin saturation (what share of transferrin is occupied by iron).

In iron-deficiency anaemia, iron and ferritin are low, TIBC is high and saturation is low; in the anaemia of chronic disease, iron is low but ferritin is normal or high; in haemochromatosis, iron, ferritin and saturation are all high. The test is done in the morning without eating, so that the result is comparable.

• When there are signs of iron deficiency: tiredness, weakness, pale skin, shortness of breath, brittle nails, hair loss
• When iron overload (haemochromatosis) is suspected
• To work out the cause of anaemia — together with ferritin, TIBC and transferrin saturation, so that iron deficiency is told apart from the anaemia of chronic disease
• To follow the effect of iron supplements or injections
• During pregnancy, in people who do sport, and on a plant-based diet

A raised iron level in the blood can point to iron overload (haemochromatosis), increased breakdown of red blood cells (haemolytic anaemia), liver damage or liver inflammation, iron poisoning, or frequent blood transfusions. Iron supplements taken recently raise it temporarily. Overload is confirmed by ferritin and transferrin saturation.

• Haemochromatosis — too much iron in the body
• Anaemia caused by red blood cells breaking down too quickly (haemolysis)
• Damage to liver tissue, or inflammation of the liver
• Iron poisoning
• Frequent blood transfusions
• Iron supplements taken recently — temporarily

Alongside a raised result, these are the things usually assessed:

• Ferritin and transferrin saturation — they confirm or rule out overload
• Whether you took supplements before the test
• Liver markers
• Family history — haemochromatosis is inherited

Low iron

A low iron level most often means iron deficiency due to long-term bleeding from the digestive tract, heavy periods, poor absorption in the gut, too little iron from food, or pregnancy. But iron also falls during an infection or a chronic illness while the stores are still sufficient — ferritin is then normal or raised. Ferritin and TIBC show the difference.

• Long-term bleeding from the digestive tract
• Heavy periods
• Bowel conditions that interfere with iron absorption
• Too little iron from food
• Pregnancy
• An infection or a chronic illness — iron is low, but the stores are there

• Tiredness, weakness
• Pale skin
• Shortness of breath during physical exertion
• Brittle nails, hair loss
• Restless legs syndrome

Alongside a low result, these are the things usually assessed:

• Ferritin — whether the stores really are depleted, or iron is low because of inflammation
• A full blood count — whether anaemia is already present
• A possible source of blood loss — particularly in men and in women after the menopause
• Conditions that interfere with absorption, and diet
• Which form to supplement with and when to repeat the test — that is for a doctor to decide

How the ranges differ for women and men

Women: per the MedlinePlus medical encyclopedia, the iron range in blood for women is 6.6–25.9 µmol/l (37–145 mcg/dl), while a wider and higher interval is given for men — 10.6–28.3 µmol/l (59–158 mcg/dl). Transferrin saturation is also lower for women: 15–45 %, compared with 20–50 % for men. The source itself does not separately explain why the intervals differ by sex, but among the reasons iron falls in women it mentions heavy menstrual bleeding and pregnancy — both of which apply only to women. When a result is assessed, it matters that it is compared specifically with the women's interval, that the scale the laboratory uses is taken into account (it can differ slightly), and whether the test was done during pregnancy, because the range then changes further.

Men: per the MedlinePlus medical encyclopedia, the iron range in blood for men is 10.6–28.3 µmol/l (59–158 mcg/dl) — higher and wider than the interval given for women, 6.6–25.9 µmol/l (37–145 mcg/dl). Transferrin saturation is also higher for men: 20–50 %, compared with 15–45 % for women. The source does not separately give a reason why the men's interval is wider, but among the causes of reduced iron it mentions neither menstrual bleeding nor pregnancy. Both factors belong only to the women's interval, while among the causes of low iron typical for men the source mentions bleeding from the digestive tract. When a result is assessed, it matters that it is compared with the men's interval, and that the scale a particular laboratory uses may differ slightly from the one given in the source.

At the Medicina practica laboratory in Lithuania an iron test costs from €7 (September 2026 pricing), and ferritin from €16.