Serum Iron

What it is

Serum iron measures the iron circulating in your bloodstream right now, which is only a tiny slice of your body's total iron. It's genuinely volatile: it varies with the time of day (often higher in the morning), with what you ate, and with anything iron-containing taken recently, so two draws days apart can look quite different. Because of that it's rarely interpreted alone — clinicians typically read it together with TIBC, transferrin saturation, and ferritin to get a picture that a single value can't give.

Typical range

Reference ranges vary between laboratories, and what is normal for you depends on your own history. Your own lab’s range is the one printed on your report.

Worth asking your clinician

• Given when my blood was drawn and what I'd eaten, how much should I read into this serum iron value?
• How does this fit with my TIBC, transferrin saturation, and ferritin?
• Is there a reason to recheck this, or does the fuller iron panel already answer the question?