Iron test: what it measures and what results mean

By Dr B.C. Gupta, MD · 2026-08-15

An iron test measures the amount of iron in your blood. Iron is essential for making haemoglobin, the part of red blood cells that carries oxygen, and for many other body functions.

What does the test measure?

An iron test usually measures serum iron, the iron in your blood, and often ferritin, which reflects the iron stored in your body. It may also include TIBC, the total iron-binding capacity, which shows how well your blood can carry iron. Together these give a fuller picture of your iron status.

How to prepare

An iron test may require fasting, and the time of day can affect the result, so confirm with the laboratory. The sample is a blood draw, and results are usually available the next day.

What a low or high result can mean

Low iron or low ferritin can point to iron deficiency, which is a common cause of anaemia and can lead to tiredness, weakness, and pale skin. High iron can indicate that the body is storing too much, which may be due to conditions such as haemochromatosis or repeated transfusions. Your doctor will interpret the results with your symptoms and other tests.

When is it ordered?

Doctors order an iron test to investigate tiredness, anaemia, or heavy menstrual bleeding, to check iron stores in pregnancy, or to monitor people on iron treatment. It is also part of some health packages.

This article is for general information only and is not medical advice. Always discuss your results and any health concerns with your doctor.