Iron deficiency: what ferritin, iron, hemoglobin, hematocrit and red blood cells on your lab report mean
What ferritin, iron and hemoglobin on your lab report mean, which ferritin cut-offs WHO and a German guideline use, and why the test is often repeated.
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Your blood test lists ferritin, iron, hemoglobin, hematocrit and red blood cells, each beside a printed range. Whether that adds up to iron deficiency is for your doctor to say. Keep the report in a folder or in Sam's Health Vault: your own copy, separate from your practice's records. This guide covers what each value shows, which ferritin cut-offs apply, and why tests are repeated.
What do ferritin, iron, hemoglobin, hematocrit and RBC mean?
| On the report | What it measures |
|---|---|
| Ferritin | A protein that stores iron. In otherwise healthy people it tracks the iron stores well. |
| Iron (serum iron) | Iron circulating in your blood at the time of the draw. It varies over the day. |
| Hemoglobin (Hb) | The iron-rich protein in red blood cells that carries oxygen. |
| Hematocrit (Hct) | The percentage of your blood made up of red blood cells. |
| Red blood cells (RBC) | The number of red blood cells. |
A low hemoglobin, hematocrit or red cell count can point to anemia. MedlinePlus lists iron deficiency among the possible reasons.
The German guideline on iron deficiency (Onkopedia, by the hematology society DGHO) describes three stages.
- Storage iron deficiency: the stores are low and ferritin falls. Red cell production still gets enough iron.
- Iron-deficient red cell production: the bone marrow runs short. Markers such as transferrin saturation change, while hemoglobin is still within the norm.
- Iron deficiency anemia: hemoglobin drops below the norm.
In iron deficiency anemia, red cells are typically smaller and carry less hemoglobin, the guideline says. On a report that shows as an MCV below 80 fL and an MCH below 28 pg.
What ferritin level counts as iron deficiency?
There is no single number; it depends on the source. For ferritin, ng/mL and micrograms per liter give the same number.
| Source | Ferritin | What it is for |
|---|---|---|
| Onkopedia guideline | below 15 ng/mL | regarded as proof of iron deficiency |
| WHO, as cited in the guideline | 15 to 150 ng/mL (women), 15 to 200 ng/mL (men) | apparently healthy people; higher values raise the question of too much iron (WHO itself uses 150 for menstruating women, 200 for men and non-menstruating women) |
| Onkopedia guideline | below 30 ng/mL | growing consensus for the lower limit in adults of either sex |
| WHO guideline, 2020 | below 70 ng/mL (adults) | with infection or inflammation; conditional, low certainty of evidence |
| Your lab | lower limit about 12 to 20 ng/mL (women), about 30 ng/mL (men) | varies by lab; population averages, not ideal values |
For hemoglobin, the guideline uses the WHO norm of 12 g/dL for women and 13 g/dL for men. When hemoglobin is below it because of iron deficiency, the guideline speaks of iron deficiency anemia.
These cut-offs are tools for your doctor, not a self-test. Your doctor reads ferritin together with hemoglobin, inflammation markers, symptoms and history. Sam, too, shows only the range printed on your report, not these cut-offs.
A worked example with invented numbers: a report shows ferritin at 22 ng/mL, printed range 15 to 150. That is inside the lab's range and above the WHO limit for healthy people. It is above the 15 ng/mL the guideline regards as proof. It is below the 30 ng/mL that, per the guideline, a growing consensus supports. With inflammation present, it would also be below the WHO cut-off of 70 ng/mL. So the same number reads differently by source. The example is invented, not a benchmark, and does not classify your own result. Do not postpone an appointment because a value looks fine.
Why can ferritin look normal when iron is low?
The Onkopedia guideline calls ferritin the most sensitive iron marker, because it falls from the first stage. Its weakness: ferritin is an acute-phase protein. Inflammation, cancer and liver disease push it up, and that can hide a deficiency.
So the guideline asks doctors to rule out significant inflammation, using the sedimentation rate (ESR), CRP and the clinical picture. WHO raises its adult cut-off to 70 ng/mL for the same reason.
Other markers react too. Transferrin saturation can be low during inflammation even when iron stores are normal. Serum iron changes over the day and is also low in the anemia of chronic disease. The guideline therefore calls measuring serum iron obsolete for diagnosing iron deficiency.
A high ferritin, in turn, can come from inflammation or point to too much iron. WHO says ferritin should not be used alone to judge too much iron, and a raised value needs a doctor's assessment.
CRP is one of the 33 values Sam matches by name on a lab report. Whether ferritin and CRP fit together is for your doctor to judge.
Which symptoms and causes are worth writing down?
The NHS names tiredness, shortness of breath, noticeable heartbeats, paler skin and headaches as the main symptoms. Less common ones include hair loss, spoon-shaped nails, restless legs and a sore tongue. The Onkopedia guideline adds exhaustion, poor concentration and sleep problems, even before anemia. All of them can have other causes.
In Sam's symptom diary you log fatigue, dizziness, shortness of breath, hair loss or restless legs per day. Each is mild, moderate or severe. Difficulty concentrating and nail changes are logged as present. There is no time of day. Sam cannot tell iron deficiency from other causes of tiredness.
The NHS describes periods as heavy when, for example, you:
- change a pad or tampon every 1 to 2 hours, or empty a menstrual cup more often than recommended.
- need two types of period product at once.
- bleed for more than 7 days.
- pass clots larger than about 2.5 cm.
- bleed through to clothes or bedding.
- skip daily activities or take time off because of your period.
Heavy bleeding is often seen as normal, the Onkopedia guideline adds, especially when periods have always been heavy. The NHS advises seeing a GP if heavy periods affect your life or have gone on for some time.
In Sam's cycle tracker you log bleeding days, spotting and the flow (light, medium or heavy). You can add effects such as "Soaked through in an hour" or "Woke me at night". Sam counts cycle length and bleeding days but does not judge flow volume.
The NHS names bleeding in the stomach or gut as another common cause. The guideline also names blood donation, pregnancy and breastfeeding, and low intake, for example on a strict vegetarian diet. Mostly, it says, iron deficiency comes from increased loss or use. Once a deficiency is found, the work-up looks for the cause. The guideline names ruling out blood loss from the digestive tract first, unless another cause is clearly present. What applies to you is for your doctor to work out.
Why is the blood test repeated?
Repeat tests have several reasons.
- Finding the cause: if the reason for anemia is unclear, the NHS says your GP may order other tests, such as a test for blood in your poo.
- Tracking the response: the NHS says your GP may repeat blood tests over the next few months. Under the guideline, hemoglobin is checked every 4 weeks until it is back to normal. Then, depending on the cause, it recommends blood count and ferritin every 3 months for about a year.
- Getting the timing right: after iron given into a vein, ferritin should be measured no earlier than 4 weeks later, the guideline says. Before that, circulating iron distorts the result.
- Comparing like with like: WHO advises staying with the same test method for follow-up. Labs also use different reference ranges, MedlinePlus notes.
Your doctor sets the schedule. If you are pregnant or planning to be, tell your doctor. The guideline lists pregnancy among the causes of a higher iron need. If symptoms get worse or new ones appear, contact your doctor sooner. When not to wait at all is in the next section.
When should you not wait for an appointment?
- Call your local emergency number (112 in the EU, 999 in the UK, 911 in the US) for chest pain or severe shortness of breath (barely able to speak). Call too for vomiting blood, black sticky stool, blood in the stool beyond traces on the toilet paper, or heavy bleeding that cannot be stopped. A racing, pounding or irregular heartbeat is an emergency too if it does not go away or comes with shortness of breath, chest pain or feeling faint. For fainting, call when it comes with chest pain or a racing or irregular heartbeat. Call too if it happens during exercise or while lying down, or comes with shaking or jerking, a serious injury or difficulty speaking or moving. Also call if the person is not breathing, cannot be woken within a minute or does not fully recover. Do not wait for it to pass, and do not drive yourself to the emergency department. Dark stool can also come from iron supplements; black, sticky stool still calls for emergency help, and if you are unsure, get it checked soon.
- Get checked by a doctor the same day for shortness of breath that is worse than usual or a new racing or irregular heartbeat that has stopped. The same goes for a very heavy period with dizziness or weakness, or bleeding that is suddenly much heavier than usual. When your practice is closed, use the urgent care service where you live (111 in the UK).
- Get checked soon for fainting without those signs once you have fully recovered, for very heavy periods and for any trace of blood in the stool.
What should you bring to the appointment?
Informedhealth.org (IQWiG) suggests earlier results, a list of your medicines, notes on your symptoms and your questions. For iron deficiency that means:
- Your lab reports with dates, older ones too. If you need copies, see getting a copy of your medical records.
- A list of everything you take, including over-the-counter products and supplements. The medication list guide covers what belongs on it.
- Your symptoms: which ones, since when, on how many days, how strong.
- If periods are part of the question: your bleeding days and how they affect your day.
- Anything linked to causes: whether you give blood, how you eat, whether you are pregnant or hoping to be.
- Your questions. Was CRP tested? Which ferritin cut-off applies to me? When is my next check, and at the same lab?
A fuller list is in the doctor appointment checklist.
In Sam's Health Vault you scan a report or add a photo or PDF. With your consent, Sam reads the values, including ferritin, iron, hemoglobin, hematocrit, red blood cells and CRP. Where a range is printed, Sam shows it next to the value. If your lab prints separate ranges for women and men, Sam can keep only one of them; check the original to see which range applies to you. Sam sets no targets of its own. Between your last two reports you see the three biggest changes, so ferritin appears only if it is one of them. Values printed in different units are not compared. There is no trend chart for ferritin. Check what Sam read against the original. Rows such as total iron binding capacity or reticulocyte hemoglobin can end up under the wrong name, and a total iron binding capacity row filed as iron can then show up as a large iron change in the comparison.
You create the monthly report for the previous month yourself. It needs notifications, access to your health data and an entry on chronic conditions ("none" counts). From the second report on, it also needs your daily status (Good, A bit off or Sick) on at least 15 of the last 30 days. The PDF shows your symptom days and top five symptoms and counts the lab reports you added. Individual lab values are not in it, so show those in the app. More in the iron deficiency overview.
Keep lab reports, symptoms and bleeding days together in Sam
You bring reports, symptom days and bleeding days to the visit in one app, instead of a folder and memory.
- Instead of a folder: with your consent, Sam reads ferritin, iron, hemoglobin, hematocrit and red blood cells from your lab reports. Where a range is printed, you see it next to the value. Between your last two reports you see the three biggest changes.
- Instead of memory: you log fatigue, dizziness or restless legs daily, with a strength, in the symptom diary.
- Instead of a paper note: the cycle tracker keeps bleeding days, flow and effects such as "Needed two products at once".
Sam cannot tell iron deficiency from other causes of tiredness, draws no trend line for ferritin and keeps no food diary. Check read values and ranges against the original. More in the iron deficiency overview.
Try Sam for freeSam is a wellness companion, not a medical device. The app does not diagnose, treat, cure or prevent any disease or health condition. Always consult qualified professionals for medical decisions.
Related reading
- What kind of doctor treats iron deficiency? Tests and steps
- Iron deficiency and heart rate: what a watch cannot measure
- Medication list for your doctor: what to include
- Doctor appointment checklist for a chronic condition
- Getting a copy of your medical records when changing doctor
- TSH results explained: hypothyroidism and your doctor visit
Sources
Updated: October 2026
- DGHO: Onkopedia guideline Eisenmangel und Eisenmangelanämie (April 2025, in German)
- WHO: Use of ferritin concentrations to assess iron status in individuals and populations (eLENA summary of the 2020 WHO guideline, updated 9 August 2023)
- NHS: Iron deficiency anaemia and Iron deficiency anaemia: treatment (last reviewed 26 January 2024)
- Healthdirect Australia: Heavy periods (last reviewed March 2026)
- NHS: Heavy periods (last reviewed 19 September 2024)
- MedlinePlus: Ferritin blood test (updated 18 March 2025), Hemoglobin test (updated 27 October 2024), Hematocrit test (updated 25 November 2024), Red blood cell (RBC) count (updated 7 October 2024) and How to understand your lab results (updated 4 September 2025)
- IQWiG (informedhealth.org): At the doctor's (updated 18 December 2024)
- NHS: Stomach ulcer (last reviewed 12 August 2025), Shortness of breath (last reviewed 30 January 2024) and Fainting (last reviewed 17 August 2026)
- MSD Manual: Gastrointestinale Blutung (reviewed June 2025, in German)
- British Red Cross: Learn first aid for an adult bleeding heavily
More on Iron Deficiency
Frequently Asked Questions
What is the difference between ferritin, iron and hemoglobin?+
Ferritin is the protein that stores iron, so it reflects your iron stores. Serum iron is the iron circulating in your blood at the moment of the draw. Hemoglobin is the iron-rich protein in red blood cells that carries oxygen. The German hematology guideline (Onkopedia) speaks of iron deficiency anemia when hemoglobin falls below the norm for age and sex because of iron deficiency, and iron deficiency can exist before that point. What your results mean for you is for your doctor to judge.
What ferritin level means iron deficiency?+
It depends on the source, and the numbers are not a self-test. The Onkopedia guideline regards a ferritin below 15 ng/mL as proof of iron deficiency and reports a growing consensus for 30 ng/mL as the lower limit in adults. With infection or inflammation, WHO says a ferritin below 70 ng/mL in adults may indicate iron deficiency. A value above these limits is not an all-clear, because ferritin can look normal when inflammation is present. Your doctor decides which cut-off fits your situation and what your result means.
Can ferritin look normal when iron is low?+
It can. Ferritin is an acute-phase protein: inflammation, cancer and liver disease push it up and can mask a deficiency. That is why the guideline advises checking for inflammation, for example CRP, when judging it, and why WHO uses a higher cut-off when infection or inflammation is present. Whether a ferritin result fits your situation is for your doctor to judge.
Is a serum iron test useful on its own?+
Not much, according to the Onkopedia guideline. Serum iron follows a daily rhythm and is also low in the anemia of chronic disease, so the guideline calls measuring it obsolete for diagnosing iron deficiency. Ferritin and, depending on the case, transferrin saturation carry more weight.
Why is my blood tested again once I start iron?+
Follow-up results show your doctor whether hemoglobin and ferritin have moved. The NHS says your GP may repeat blood tests over the next few months. Under the Onkopedia guideline, hemoglobin is checked every 4 weeks until it is back to normal, then blood count and ferritin every 3 months for about a year, depending on the cause. After iron given into a vein, ferritin is measured no earlier than 4 weeks later, because circulating iron distorts the result. Your doctor sets the schedule. If symptoms get worse or new ones appear, contact your doctor sooner.
Can heavy periods cause iron deficiency?+
Yes. The NHS names heavy periods and pregnancy as very common causes of iron deficiency anemia. For women of reproductive age, the Onkopedia guideline names menstrual blood loss as the most important cause, and gives about 5 to 10 percent for iron deficiency in Europe overall and about 20 percent in that group. Whether a period counts as heavy is for your doctor to judge. In Sam's cycle tracker you log bleeding days, flow and how the bleeding affected your day; Sam does not judge flow volume.
What should I bring to an appointment about iron deficiency?+
Your lab reports with dates, older ones too, a list of everything you take including over-the-counter products and supplements, the days you had symptoms and, if periods are part of the question, your bleeding days. Add your questions, for example whether CRP was tested and when the next check is due.
When should I not wait for an appointment?+
Call your local emergency number (112 in the EU, 999 in the UK, 911 in the US) for chest pain or severe shortness of breath (barely able to speak). Call too for vomiting blood, black sticky stool, blood in the stool beyond traces on the toilet paper, or heavy bleeding that cannot be stopped. A racing, pounding or irregular heartbeat is an emergency too if it does not go away or comes with shortness of breath, chest pain or feeling faint. For fainting, call when it comes with chest pain or a racing or irregular heartbeat. Call too if it happens during exercise or while lying down, or comes with shaking or jerking, a serious injury or difficulty speaking or moving. Also call if the person is not breathing, cannot be woken within a minute or does not fully recover. Dark stool can also come from iron supplements; black, sticky stool still calls for emergency help, and if you are unsure, get it checked soon. Get checked by a doctor the same day for shortness of breath that is worse than usual or a new racing or irregular heartbeat that has stopped. The same goes for a very heavy period with dizziness or weakness, or bleeding that is suddenly much heavier than usual. When your practice is closed, use the urgent care service where you live (111 in the UK). Get checked soon for fainting without those signs once you have fully recovered, for very heavy periods and for any trace of blood in the stool.