Iron deficiency and anaemia

Iron sits at the centre of haemoglobin, the protein inside red cells that carries oxygen from the lungs to every tissue. It is also needed by the enzymes that generate energy inside cells, which is why iron deficiency is felt in muscles, hair follicles, nails and concentration, and not only in the blood count.

The most useful idea on this page is that iron deficiency is one process passing through stages, not two separate conditions. Stores go first: ferritin falls as the reserve in the liver, spleen and bone marrow is drawn down. Next, the marrow starts building red cells with less iron than it would like — cells become smaller and paler, and the report shows a falling MCV and a rising RDW. Only at the end does haemoglobin drop far enough to be labelled anaemia. Symptoms can arrive at any point along that path. Someone with a haemoglobin of 12 g/dL and a ferritin of 8 ng/mL is not healthy with a stray number; she is early in the same process, and that is the stage at which it is easiest to correct.

This matters enormously in India. The National Family Health Survey (NFHS-5, 2019-21) found roughly 57% of women aged 15-49 anaemic, about 25% of men, and around 67% of children aged 6-59 months. Those figures are among the highest reported anywhere. They are also debated — the survey used capillary (finger-prick) sampling, and Indian studies comparing capillary with venous samples suggest capillary testing overestimates how many people are anaemic. The haemoglobin cut-offs themselves are under review internationally. The honest position is that anaemia is genuinely widespread here and that the headline percentage is probably somewhat too high.

Why so common? Indian diets are predominantly plant-based, and plant iron is non-haem iron, absorbed at a far lower rate than the haem iron in meat, fish and eggs. Phytates in whole grains and legumes bind it. Polyphenols in tea and coffee bind it too, which makes chai with breakfast and chai straight after lunch a real and specific problem. Calcium from milk and dairy competes for the same absorption pathway. Vitamin C would help considerably, and lemon, amla and guava are everywhere, yet they rarely appear at the meal itself.

Then there is loss. Heavy menstrual bleeding is the single largest cause in Indian women and is so normalised that it is rarely mentioned unless asked about directly. Closely spaced pregnancies drain stores faster than they refill. Hookworm and other intestinal parasites remain relevant in parts of the country. And in men and postmenopausal women, slow bleeding from the gut — an ulcer, long-term painkiller use, or a colorectal lesion in anyone past 45 — is the cause that must not be missed.

Demand rises at particular stages, and Indian diets rarely rise with it. Adolescence adds rapid growth and, in girls, the onset of menstruation at the same time. Pregnancy roughly doubles the requirement, and pregnancies spaced closely together leave no interval in which stores can rebuild. Breastfeeding continues the draw.

Absorption can also fail. Coeliac disease is genuinely under-diagnosed in North India and often shows up first as iron deficiency that does not respond to tablets. Atrophic gastritis, H. pylori infection, long-term acid suppression and previous bariatric surgery all reduce iron uptake, because iron needs stomach acid to be absorbed well.

ⓘThis information is educational and not a diagnosis.

The classic picture — pallor, breathlessness, palpitations — belongs to the late stage. Most people arrive long before that, describing something vaguer: tiredness that rest does not repair, a heaviness in the legs, poor stamina at the gym, breathlessness on one flight of stairs that was fine last year, headaches, and difficulty holding concentration through a working afternoon — a foggy, slowed-down feeling that most people put down to workload before they think of iron.

There are quieter clues worth knowing. Hair fall that is diffuse rather than patchy. Brittle, ridged or spooned nails. Cracking at the corners of the mouth, and a smooth, sore tongue. Restless legs at night, which has a strong and often missed association with low iron stores. Pica — a craving for ice, raw rice, mud or chalk — is unusual enough that it is close to diagnostic when it appears.

In women, the history that matters most is the menstrual one: periods lasting more than seven days, flooding, clots larger than a rupee coin, changing protection hourly. Many women describe this as normal because it is what they have consistently had, and because their mothers and sisters describe the same. Perimenopause makes it heavier still, which is why iron deficiency so often surfaces in the forties.

Pallor is looked for in the lower eyelid, the tongue and the nail beds rather than the face, and it is an unreliable sign in the early stages. The features listed below sit in a different category — they suggest active bleeding or a heart under strain, and they warrant prompt assessment rather than a routine appointment.

The purpose of testing is to answer two questions in order: is iron deficiency present, and what is causing it. Correcting the first without answering the second is where most treatment goes wrong.

The full blood count gives the shape of the problem. A low MCV and MCH describe small, pale cells; a raised RDW says the marrow is producing cells of varying size, which often appears before the MCV falls. A normal MCV is not reassurance — coexisting vitamin B12 or folate deficiency enlarges cells and can cancel out the shrinking effect entirely, leaving a normal-looking index over two deficiencies. Mixed deficiency is common in Indian vegetarian diets, and this is a good reason to check B12 alongside iron rather than after it.

Ferritin is the single best test of iron stores, and its limitation deserves equal billing. Ferritin is an acute-phase reactant: it rises with infection, inflammation, obesity and liver disease. A person with rheumatoid arthritis or a recent fever can be iron deficient with a ferritin that reads comfortably normal. Pairing ferritin with CRP is what protects against that error.

The thresholds in common use: a ferritin below about 30 ng/mL generally indicates deficiency, below 15 is regarded as diagnostic, and where inflammation is present a higher threshold of around 100 ng/mL is often applied instead. Laboratories and guidelines differ on these figures, so a result is best read against the reporting lab's own range and the clinical picture rather than a remembered number. Transferrin saturation below roughly 20% supports the diagnosis and is particularly useful when ferritin is clouded.

Beyond confirming deficiency, testing turns to cause. Coeliac serology (tissue transglutaminase antibodies, with total IgA) is worth doing in unexplained cases, and it needs to be taken while gluten is still being eaten. Faecal occult blood testing has a place, though a negative result does not exclude bleeding. Endoscopy and colonoscopy are the standard next step for unexplained iron deficiency in men and in postmenopausal women, and for anyone with bowel symptoms or a family history.

One point specific to India: thalassaemia trait is common across many communities, and it produces small red cells that mimic iron deficiency closely. Haemoglobin HPLC measuring HbA2 distinguishes them. This genuinely matters, because iron given to someone with thalassaemia trait who is not deficient does not help and carries no benefit to offset it.

Food, honestly described. Haem iron from meat, fish, chicken and liver is absorbed at roughly 15-35%; non-haem iron from plants at closer to 2-10%. For a vegetarian household that means volume and pairing matter more than any single ingredient. Ragi, bajra, jowar, amaranth, sesame and til, dates, jaggery, dals, chana, soya, and green leafy vegetables are the realistic sources. Spinach is a weaker source than its reputation suggests — the reputation traces to a nineteenth-century decimal-point error that inflated its iron content tenfold, and its oxalates limit absorption further. Cooking in an iron kadhai adds a small amount, and it is a genuine contribution rather than a solution.

Timing does real work. Vitamin C at the meal itself — lemon squeezed over dal, amla, guava, tomato, citrus — can multiply non-haem absorption several times over. Tea and coffee taken with or within an hour of a meal cut it substantially, so moving chai to the mid-morning gap rather than beside the plate is one of the most practical changes available in an Indian kitchen. Calcium supplements and large quantities of milk are best separated from iron-rich meals for the same reason.

Oral iron, explained rather than prescribed. Preparations differ in the amount of elemental iron they deliver: ferrous sulphate, fumarate, ascorbate, bisglycinate and carbonyl iron carry different elemental fractions, so two tablets of the same milligram strength are not equivalent. Recent evidence on hepcidin — the hormone that shuts down iron absorption for roughly a day after a dose — supports alternate-day dosing, which in trials achieved similar or better absorption than daily dosing with fewer side effects. Nausea, metallic taste, constipation and darkened stools are the common complaints, and they are the main reason courses are abandoned early. Haemoglobin usually responds over weeks; stores take months. Which preparation, what schedule, and for how long are decisions for your doctor.

Intravenous iron is considered when oral iron is not tolerated, not absorbed, when losses outpace replacement, or when correction is needed quickly. It is now widely available in India, including in day-care settings, and it is a clinical decision rather than a consumer choice.

And the cause. Treating heavy menstrual bleeding, eradicating H. pylori, managing coeliac disease, reviewing long-term painkillers, investigating the gut — this is the part that determines whether the deficiency stays corrected. Iron deficiency is a symptom, not a diagnosis.

Most people meet this condition as a single line on a report: haemoglobin 10.4, ferritin 11. What that line means depends entirely on the stage you are at, the reason behind it, and what else on the same page is doing.

If you would like to work through how to read your own blood report — what MCV, RDW and ferritin are telling you, how inflammation distorts them, and which numbers deserve a follow-up — the Learning Session below covers exactly that in a small group, with time for questions.

If you have reports in hand and a history that needs unpicking — heavy periods, a vegetarian diet, tablets that have not worked — that is a conversation for a consultation rather than an article.