Serum iron test: iron level normal range and what results mean

A serum iron test measures the iron circulating in your blood when the sample is taken, most of it carried by transferrin, the blood's main iron-transport protein. It is a useful number but a restless one. Serum iron moves with meals, supplements, inflammation and from one day to the next, so doctors read it with ferritin, TIBC and transferrin saturation rather than on its own.

What serum iron measures

Iron reaches the blood from two places: food absorbed through the gut, and iron recycled from old red cells by scavenger cells called macrophages. Transferrin carries it to the bone marrow, where it is used to make haemoglobin for new red cells. Serum iron is the amount in transit at one moment. It is not a measure of stores, which is what ferritin shows.

Because it moves so much, serum iron is a weak test on its own. Mayo Clinic Laboratories advises against using its iron and TIBC test as the primary test for iron deficiency and recommends ferritin instead, and a 2025 review notes that no single serum iron result can diagnose iron deficiency and that its main use is to calculate transferrin saturation.

Iron level normal range

Serum iron is reported in µmol/L or µg/dL (1 µg/dL is about 0.179 µmol/L). Ranges differ by laboratory, method, age and sex, so the range on your own report is the one to read your result against. Three published adult examples:

Because serum iron varies so much between samples, a result just outside the range is read alongside ferritin and transferrin saturation before anything is concluded.

What a high serum iron usually points to

A high result can simply reflect timing, since iron levels shift with recent iron intake, which is why some laboratories ask for a gap after iron supplements. A haemolysed sample, where red cells broke open in the tube, can also read high. Beyond those, MedlinePlus lists too much iron in the body (haemochromatosis), haemolytic anaemia, liver damage or hepatitis, iron poisoning and frequent blood transfusions.

A doctor will usually look at transferrin saturation and ferritin together. If both are raised, the doctor may check liver blood tests and, depending on ancestry and family history, consider genetic testing for haemochromatosis.

What a low serum iron usually points to

A low serum iron can mean the body is short of iron, from long-term bleeding in the gut, heavy periods, a diet with little iron, problems absorbing iron, or pregnancy. It can also fall with inflammation even when stores are adequate: inflammation raises the hormone hepcidin, which keeps iron held inside cells.

The next step is usually ferritin, often with a marker of inflammation such as CRP. Low iron with a low ferritin points to depleted stores. Low iron and a low transferrin saturation with a normal or high ferritin fits iron held back by inflammation.

What moves serum iron

• Time and day. In a Mayo Clinic study of 20 healthy adults sampled at 8 am, noon and 4 pm and again the next morning, serum iron moved through the day with no consistent pattern. Morning levels were higher than afternoon levels in about half of the people, and the change from one day to the next was similar to the change within a day.
• Food and supplements. Iron intake shifts serum iron, and iron treatment raises serum iron and transferrin saturation within one to two weeks.
• Inflammation. Serum iron can change quickly and sharply during inflammation.
• Pregnancy. MedlinePlus lists pregnancy among the causes of a low level.
• Medicines. Several can affect the result, including the contraceptive pill and oestrogens, testosterone, some antibiotics, and some blood pressure, cholesterol and gout medicines.
• Transfusions. Frequent blood transfusions raise serum iron.
• The sample. Haemolysis, red cells breaking open in the tube, pushes the measured iron up.

Preparing for the test

Mayo Clinic Laboratories prefers an 8-hour fast and a sample before noon, though neither is required, and asks that iron-containing supplements are not taken in the 24 hours before collection. MedlinePlus says the test is usually done in the morning or after fasting. Follow the instruction your doctor or laboratory gives you. Do not stop or change a medicine on your own; tell the person taking the sample what you take and when you last took it, and mention any recent transfusion.

How Clare's panel handles it

In Clare's panel, serum iron is measured by the lab. Clare then uses it with TIBC, also measured by the lab, to calculate two more results: transferrin saturation (serum iron ÷ TIBC × 100) and UIBC (TIBC minus serum iron). Ferritin and hs-CRP are in the same panel, so serum iron is read with them.

Why it matters in the UAE

Small red cells are common in UAE studies, and iron deficiency and thalassaemia trait are both frequent causes. In 394 healthy young Emirati adults, 45% had an MCV below 80 fL, 65% of the women had a ferritin below 30 µg/L, and alpha-thalassaemia trait was estimated in 32% of the men. Iron studies help tell the two apart. When red cells are small but iron results are normal, the British Society of Gastroenterology recommends haemoglobin electrophoresis, which looks for thalassaemia and related conditions.

Price

The prices we read did not list serum iron on its own; it is usually sold within an iron and ferritin test. When we read public prices on 11 October 2026, an iron or ferritin test cost from 55 to 1,200 at 9 UAE providers. The lowest prices were for ferritin alone, so a panel that includes serum iron sits higher in that range. VAT was rarely stated, some prices were offers or indicative figures, and home collection can add a fee.

Related tests

Serum iron is read with ferritin, which shows the stores behind it, with transferrin saturation, which Clare calculates from it, and with hemoglobin from the CBC blood test. For how these fit into a full panel, see what to expect from a comprehensive blood test in Dubai.

Why serum iron means more over time

Because serum iron moves so much from one sample to the next, a single value is a weak guide; British haematology guidance notes that this variability limits the use of transferrin saturation, which is built from serum iron, on its own. Across several tests, the trend in ferritin and transferrin saturation says more than any one serum iron result. Once iron deficiency anaemia has been treated, the British Society of Gastroenterology recommends periodic blood counts, perhaps every 6 months at the start. Clare is opening in the UAE with a waitlist at clare.health.