Original Rebuild article · Understanding labs
Normal hemoglobin.
Low iron stores.
Your blood count can look normal while your iron stores are running low.
A ferritin of 24 ng/mL can be labeled “normal” and still meet a current guideline’s criterion for iron deficiency.
The lab’s reference range and a clinical decision threshold can differ.
If only a CBC was checked, “you’re not anemic” does not settle the iron question.
Four things worth discussing at your next visit:
1. Read the actual ferritin number.
The September 2026 American Society of Hematology diagnosis guideline suggests a cutoff of 30 ng/mL or below for nonpregnant adults without known or suspected inflammation. Symptoms or ongoing risk factors can make a threshold of 50 ng/mL or below appropriate.
These are conditional recommendations with low-certainty evidence. They are not universal “optimal” targets.
2. Ask whether inflammation is changing the picture.
Ferritin can rise with inflammation. At the same time, inflammation can raise hepcidin, a hormone that reduces iron transfer from the gut and storage cells into the bloodstream.
So depleted stores and restricted iron availability are different problems. They can also coexist.
In adults with anemia of inflammation, ASH suggests ferritin plus transferrin saturation, which helps assess available iron. The guideline’s discussion of ferritin below 100 belongs to that context. It does not mean everyone needs ferritin above 100.
3. Find out why iron is low.
Heavy periods. Frequent blood donation. Inadequate intake. Poor absorption, including celiac disease. Sometimes gastrointestinal blood loss.
The next question is bigger than “Which iron supplement?” Replacing iron without addressing an ongoing loss leaves part of the problem unresolved.
4. Measure the response.
In a 12-week randomized trial of 198 nonanemic menstruating women with fatigue and ferritin below 50, iron improved fatigue more than placebo. Quality of life, depression and anxiety did not significantly improve.
That supports evaluating selected patients. It does not make iron a cure for every tired person. If treatment is started, agree on when to reassess symptoms and repeat relevant labs.
Before your next visit, gather your actual CBC and ferritin results, bleeding/donation history, medications and supplements.
Then ask:
“Did we assess my iron stores, and what could explain a low result?”
Persistent fatigue deserves a full evaluation. Don’t start high-dose iron from a social post; excess iron can be harmful.
A useful functional-medicine conversation connects symptoms, labs and causes, then checks whether the person actually improves.
Sources
ASH: American Society of Hematology 2026 guidelines for diagnosis of iron deficiency
Trial: Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin