Ferritin and Haemoglobin: How to Read Them Together
The short answer
Ferritin reflects iron stores. Haemoglobin reflects the end result: how much oxygen-carrying protein the red cells contain. Iron stores fall first and haemoglobin falls last, so the two markers describe different points on the same timeline.
Read together, they show whether iron deficiency is present, how far it has progressed, and whether something other than iron is driving a low haemoglobin.
Which marker moves first
Iron deficiency develops in three stages, and each stage shows up in a different marker.
- Stores run down. Ferritin falls. Haemoglobin and the red cell indices are still normal.
- Supply to the bone marrow tightens. Transferrin saturation falls and transferrin rises. Haemoglobin may still be in range.
- Anaemia appears. Haemoglobin falls, then MCV and MCH fall as new red cells are made smaller and paler.
This is why a normal haemoglobin does not rule out iron deficiency. Clinical and functional effects of iron deficiency can occur without anaemia (Pasricha et al., 2021).
Four combinations and what each may indicate
Most results fall into one of four combinations. Each is a starting point for further assessment, not a diagnosis.
| Ferritin | Haemoglobin | What it may indicate | Read next |
|---|---|---|---|
| Low | Normal | Iron deficiency without anaemia | Transferrin saturation, MCV, MCH, diet and blood loss history |
| Low | Low | Iron deficiency anaemia | MCV, MCH, RDW. The cause of the iron loss needs medical investigation. |
| Normal or high | Low | Anaemia from another cause, or iron deficiency masked by inflammation | CRP, transferrin saturation, B12, folate, eGFR |
| High | Normal | Inflammation, liver disease, alcohol, obesity or iron overload | CRP, liver enzymes, transferrin saturation. Refer if it persists. |
Serum iron on its own should not be used to diagnose iron deficiency (Pasricha et al., 2010). It swings with recent meals and supplements.
Published thresholds, and the inflammation problem
Thresholds differ between guidelines, which is itself useful to know when a result sits near a line.
| Marker | Threshold | Source |
|---|---|---|
| Ferritin, healthy adults | Below 15 µg/L indicates iron deficiency | WHO, 2020 |
| Ferritin, adults with infection or inflammation | Below 70 µg/L may indicate iron deficiency | WHO, 2020 (conditional recommendation, low certainty evidence) |
| Haemoglobin, non-pregnant women aged 15 to 65 | Below 120 g/L defines anaemia | WHO, 2024 |
| Haemoglobin, men aged 15 to 65 | Below 130 g/L defines anaemia | WHO, 2024 |
Ferritin is an acute phase protein. It rises with infection and inflammation regardless of iron stores, and it can also be raised by liver disease, obesity and malignancy. Inflammation also withholds iron from the plasma through the hormone hepcidin (Pasricha et al., 2021).
The practical rule: never read ferritin without CRP. A ferritin of 40 µg/L means something different when CRP is raised.
When to refer, and where a platform helps
Iron deficiency is a finding that needs a cause. Australian and international guidance is clear on who needs medical investigation.
- Men and postmenopausal women with iron deficiency anaemia should be referred for gastrointestinal investigation to exclude bleeding, including malignancy (Pasricha et al., 2010; Pasricha et al., 2021).
- Anyone with iron deficiency anaemia should be assessed for coeliac disease.
- Haemoglobin below the laboratory's interval goes to the GP, whatever the ferritin.
- Persistently high ferritin with raised transferrin saturation needs medical assessment for iron overload.
Reading ferritin, haemoglobin, the red cell indices and CRP together is a pattern task. Beyond Normal groups related markers into clinical clusters, shows each against conventional and functional intervals, and charts them across visits so a falling ferritin is visible before haemoglobin moves. To compare tools, see the best online platforms for practitioners to interpret blood tests.
Related reading: how to interpret a full blood count and how to track pathology changes over time.
Frequently asked questions
Can ferritin be low when haemoglobin is normal?
Yes. Iron stores are used up before haemoglobin falls. Low ferritin with normal haemoglobin is iron deficiency without anaemia.
Can ferritin be normal in iron deficiency?
Yes. Ferritin rises with inflammation, so it can sit in range while iron stores are low. The World Health Organization suggests a higher ferritin threshold of 70 µg/L for adults with infection or inflammation.
What ferritin level indicates iron deficiency?
The World Health Organization uses below 15 µg/L for healthy adults. Some guidelines, such as NICE in the United Kingdom, use below 30 µg/L. Laboratory intervals vary.
What does high ferritin with normal haemoglobin mean?
It most often reflects inflammation, liver disease, alcohol or obesity. Iron overload is one possibility and needs transferrin saturation and medical assessment.
Which tests should be read with ferritin?
Haemoglobin, MCV, MCH, RDW, transferrin saturation and CRP.
Sources
Journal citations were checked against PubMed on 4 October 2026.
- World Health Organization. Use of ferritin concentrations to assess iron status in individuals and populations. 2020.
- World Health Organization. Guideline on haemoglobin cutoffs to define anaemia in individuals and populations. 2024.
- Pasricha SR, Flecknoe-Brown SC, Allen KJ, et al. Diagnosis and management of iron deficiency anaemia: a clinical update. Med J Aust. 2010;193(9):525-532. doi:10.5694/j.1326-5377.2010.tb04038.x
- Pasricha SR, Tye-Din J, Muckenthaler MU, Swinkels DW. Iron deficiency. Lancet. 2021;397(10270):233-248. doi:10.1016/S0140-6736(20)32594-032594-0>)
