All Conditions
Condition Guide

Iron Deficiency Anaemia

Iron deficiency is the most common nutritional disorder in the world, affecting over 2 billion people. It causes fatigue, weakness and poor concentration. The key is finding WHY iron is low, not just replacing it.

Written by Suman Konda, Clinical Pharmacist · Based on peer-reviewed sources · Editorial policy · Not medical advice

Last reviewed and updated: · How we check our content

What iron deficiency anaemia is

Iron is essential for making haemoglobin, the protein in red blood cells that carries oxygen. When iron runs short, the marrow produces red cells that are small (microcytic) and pale (hypochromic) and carry less oxygen — this is iron deficiency anaemia (IDA), the most common cause of anaemia worldwide and the most common nutritional deficiency.

IDA develops in stages: first the iron stores (ferritin) deplete, then transport iron (serum iron) falls, and only finally does haemoglobin drop and anaemia appear. That sequence is why ferritin is the earliest warning — it can fall weeks to months before anaemia develops. Typical symptoms are fatigue, weakness and poor concentration, though early deficiency can be subtle.1

How iron deficiency is usually evaluated

No single test tells the story; the pattern across iron studies does:

TestIron deficiency pattern
HaemoglobinLow in anaemia — but can still be normal in early deficiency
FerritinLow (below 30 ng/mL suggests deficiency); the earliest marker
Serum ironLow
TIBCHigh — the body makes more transferrin to scavenge iron
Transferrin saturationLow (below 16%)
MCVLow, below 80 fL (microcytic)

One caveat: ferritin is also an acute-phase reactant, so it can look falsely normal during illness or inflammation. When suspicion stays high despite a normal ferritin, soluble transferrin receptor — less affected by inflammation — can help clarify. The master regulator behind all this is hepcidin, a liver hormone that controls iron absorption: when stores fall, hepcidin drops and absorption rises; when inflammation strikes, hepcidin rises and traps iron inside cells.5

Your next steps if iron deficiency is found

  1. Find the cause — it matters as much as replacing the iron. In men and postmenopausal women, unexplained IDA should prompt investigation for gastrointestinal blood loss; in premenopausal women, menstrual history comes first.
  2. Ask about absorption blockers. Coeliac disease, gastric bypass and long-term PPI use (less stomach acid means less iron absorbed) can all underlie deficiency.
  3. Discuss replacement options with your doctor. Oral iron suits mild-to-moderate deficiency, while IV iron is used for severe deficiency, malabsorption or intolerance of oral iron. The choice, timing and duration are medical decisions.
  4. Ask what affects absorption. Vitamin C taken alongside can help; tea, coffee and calcium around the dose can hinder. Because the hepcidin response peaks after a dose and temporarily blocks further absorption, researchers have studied how dose timing affects total uptake — ask your doctor about scheduling rather than improvising.
  5. Plan a recheck. Ferritin and haemoglobin should be remeasured to confirm stores are actually refilling, and the underlying cause should be treated so the deficiency does not recur.

ICD-10-CM diagnosis codes

Iron deficiency is coded differently depending on whether anaemia has developed:

ICD-10-CM codeDescription
D50.9Iron deficiency anemia, unspecified
D50.0Iron deficiency anemia secondary to chronic blood loss
D50.8Other iron deficiency anemias
E61.1Iron deficiency (without anemia)

Codes shown are from the current ICD-10-CM classification (FY2026) and are provided for general reference. Clinical coding is performed by trained coders using the full medical record.

Practical notes

Iron studies are a panel, not a single number — haemoglobin, ferritin, serum iron, TIBC and transferrin saturation each tell a different part of the story. Keep the complete panel together in date order rather than filing reports separately, and note any recent infections beside the date, since ferritin rises with inflammation and can mask deficiency. Trends across months show whether stores are genuinely rebuilding.

What you take and when affects iron interpretation. Note all iron supplements, multivitamins, antacids and calcium tablets, since calcium and antacids reduce iron absorption. Recent blood donation, heavy menstrual periods, or any visible blood loss are essential context for your doctor. For menstruating women, roughly where you are in your cycle can also be worth mentioning.

Doctors discussing iron deficiency usually ask about diet patterns — particularly vegetarian or vegan diets, tea or coffee with meals (which reduce iron absorption), and vitamin C intake with meals (which improves it). These are general factors to discuss, not prescriptions; the underlying cause of the deficiency always needs identifying first, especially in men and postmenopausal women.

Follow-up blood tests after starting iron replacement are typically scheduled by your doctor — often after a few months — to check whether haemoglobin and ferritin are responding. Iron stores rebuild slowly, so patience matters, and your doctor decides when re-testing is useful. Report side effects or lack of improvement rather than quietly stopping.

In India

A complete blood count in India typically costs in the ballpark of ₹200–₹400, and iron studies (ferritin, serum iron, TIBC) generally add a few hundred rupees more — though prices vary by city and lab. Anaemia work-ups are among the most commonly ordered tests, so most labs offer them as affordable bundled packages.

NABL-accredited labs are available in every major Indian city, and home sample collection makes fasting morning samples straightforward. Nutritional deficiencies are common in India, so doctors here interpret iron studies routinely — and as always, the reference range printed on your own report is the one that counts.

Frequently asked questions

What is iron deficiency anaemia?

It occurs when there is not enough iron in the body to produce adequate haemoglobin. Without iron, red cells become small (microcytic) and pale (hypochromic) and carry less oxygen. It is the most common cause of anaemia worldwide and the most common nutritional deficiency.

What causes iron deficiency?

Blood loss is the most important cause: gastrointestinal bleeding in men and postmenopausal women, and heavy menstrual periods in premenopausal women. Inadequate intake or absorption also matters — vegetarian diets, pregnancy, coeliac disease, gastric bypass and long-term PPI use.

Why is ferritin the first test to fall?

Ferritin is the iron storage protein — the body’s iron reserve. When iron intake or absorption is inadequate, the body draws on reserves first, so ferritin falls before haemoglobin, serum iron or MCV change. One caveat: ferritin rises with inflammation, so it can look falsely normal during illness.

What is hepcidin, the hormone that regulates iron absorption?

Hepcidin, made by the liver, is the master regulator of iron balance. It binds ferroportin — the channel that exports iron from gut cells into the blood — and shuts it down. Low iron stores suppress hepcidin (absorption rises); inflammation raises it (iron gets trapped inside cells). This biology is why researchers study dose timing, and why inflammation causes a functional iron deficiency even when stores look adequate.

What is the treatment of iron deficiency?

Crucially: always find and treat the cause. In men and postmenopausal women, unexplained IDA usually prompts investigation for GI bleeding. Iron itself is replaced orally for mild-to-moderate deficiency or by IV infusion for severe deficiency, malabsorption or intolerance — the choice is made with your doctor, alongside dietary iron.

My haemoglobin is normal but ferritin is low — is that a problem?
It can be an early stage: ferritin reflects iron stores and typically falls before haemoglobin does. Whether it needs treatment depends on your symptoms, the degree of depletion and the likely cause — this is a judgment call for your doctor. Bring the full iron panel, not just the haemoglobin value.
Can I take iron tablets with my morning tea?
Tea and coffee with or just after meals can reduce iron absorption, so many doctors suggest keeping some gap — but the exact routine should come from your doctor or pharmacist, who know your full medicine list. Calcium tablets and antacids have a similar effect. Mention everything you take so the timing advice fits your case.
How long does it take to correct iron deficiency?
Rebuilding iron stores is gradual — typically measured in months rather than weeks — and your doctor will schedule repeat blood tests to confirm progress. If numbers are not improving, the cause may need re-examining rather than simply continuing the same approach. Discuss the expected timeline and review dates with your doctor.
Should vegetarians worry more about iron deficiency?
Plant-based diets provide non-haem iron, which the body absorbs less efficiently than the haem iron in meat — so vegetarians do need to pay more attention, though deficiency is by no means inevitable. Pairing iron-rich foods with vitamin C sources and avoiding tea with meals are commonly discussed strategies. A blood test, not diet assumptions, is what confirms deficiency — discuss testing with your doctor.

References

The clinical information on this page is based on peer-reviewed sources indexed in PubMed, the biomedical literature database of the US National Library of Medicine.

  1. Rusch JA, van der Westhuizen DJ, Gill RS, Louw VJ. Diagnosing iron deficiency: controversies and novel metrics. Best Pract Res Clin Anaesthesiol. 2023;37(4):451-467. doi:10.1016/j.bpa.2023.11.001 · PMID 39764832
  2. Ford J. Red blood cell morphology. Int J Lab Hematol. 2013;35(3):351-7. doi:10.1111/ijlh.12082 · PMID 23480230
  3. Iron Supplementation. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK557376
  4. Iron. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK542171
  5. Chibanda LN, Thomas M, Sheehy O, et al. Hepcidin as a diagnostic marker for iron deficiency in adults: a systematic review. Br J Haematol. 2023;203(3):430–443. PMID 37686128 · doi:10.1111/bjh.19069
  6. Cotter J, Baldaia C, Ferreira M, et al. Diagnosis and treatment of iron-deficiency anemia in gastrointestinal bleeding: A systematic review. World J Gastroenterol. 2020;26(45):7242–7257. PMID 33362380 · doi:10.3748/wjg.v26.i45.7242
  7. Peyrin-Biroulet L, Williet N, Cacoub P. Guidelines on the diagnosis and treatment of iron deficiency across indications: a systematic review. Am J Clin Nutr. 2015;102(6):1585–94. PMID 26561626 · doi:10.3945/ajcn.114.103366
Medical Disclaimer: This page is for general educational purposes only and does not constitute medical advice. Always consult a qualified doctor for diagnosis and treatment.
Written and medically reviewed by Suman Konda, Clinical Pharmacist · Sources linked to PubMed · Not medical advice: see our disclaimer