Iron

What it is

Serum iron measures the amount of iron circulating in your blood, bound to a transport protein.

Why it matters

It is part of assessing iron status, read together with ferritin, TIBC and transferrin saturation.

What high values can mean

A higher value can reflect iron overload, supplements or recent intake, and is interpreted with the other iron tests.

What low values can mean

A lower value can point to iron deficiency or blood loss.

How to improve it

For low iron, iron-rich foods and, when advised, supplements help; pair with vitamin C for absorption.

Food & lifestyle

Red meat, beans, lentils and fortified cereals supply iron; vitamin C aids absorption, while tea/coffee with meals reduces it.

Preparing for the testFasting required

A blood test; morning, fasting samples are often preferred because iron varies through the day — follow your lab.

When to talk to a doctor

Discuss abnormal iron with a doctor, who reads it with ferritin and the full iron panel.

Related markers

• Ferritin
• Hemoglobin
• TIBC
• Transferrin Saturation

Sources

• MedlinePlus (NIH)
• NIH Office of Dietary Supplements

Content reviewed on June 26, 2026