Can you be iron deficient even with normal haemoglobin levels?

Iron deficiency can develop gradually, with the body’s stored iron being depleted before there is a measurable fall in haemoglobin. So, a normal haemoglobin level does not always mean that the body has adequate iron stores.Steve Thomas A., consultant haemato-oncologist, Apollo Speciality Hospitals, Vanagaram, Chennai, explains that haemoglobin and ferritin measure different things. Haemoglobin is the protein in red blood cells that carries oxygen, while ferritin reflects the body’s iron reserves. The body can maintain haemoglobin for some time by drawing on these reserves. As a result, iron deficiency may be present even when a routine blood test shows normal haemoglobin.Ferritin is one of the key markers used to assess these iron stores. Gopinathan M., consultant, haemato-oncology (BMT), MGM Cancer Institute, compares ferritin to a warehouse where iron is stored for use whenever the body needs it. Iron is stored mainly in tissues such as the liver and spleen and within cells called macrophages. It is subsequently mobilised for erythropoiesis, the process through which red blood cells and haemoglobin are produced. Iron deficiency without anaemia, therefore, can be missed if testing is limited to just haemoglobin measurement. In India, the latest available NFHS-5 data showed that 57% of women aged 15-49 years live with anaemia. Ferritin levelsFerritin is an important marker of iron stores, but there is no single number that can be interpreted in isolation for everyone. Dr. Gopinathan says, along with ferritin, serum iron and total iron-binding capacity are assessed to calculate transferrin saturation. A transferrin saturation below 20% can support a diagnosis of iron deficiency, particularly when ferritin is difficult to interpret.Dr. Thomas, however, cautions against treating ferritin cut-offs as universal rules. Age, sex, pregnancy, menstruation and a person’s clinical history can influence how the result should be interpreted.Inflammation is particularly important. Ferritin is also an acute-phase reactant, meaning its level can rise during infection or inflammation. This can make iron stores appear better than they actually are. The World Health Organization recommends taking inflammation into account when interpreting ferritin and, where appropriate, using markers such as C-reactive protein alongside it.This is why a ferritin value that appears to be within a laboratory’s reference range does not necessarily rule out iron deficiency in a person who has inflammation or chronic illness.Who is affected?Iron stores can gradually decline when iron loss continues or the body’s requirements increase. Women who have heavy or prolonged menstrual bleeding are particularly vulnerable. Pregnancy also increases iron requirements. Frequent blood donors can lose significant amounts of iron through repeated donations. People who follow vegetarian diets may also be at risk because the iron in plant foods is generally less readily absorbed than haem iron from animal foods.Chronic, unnoticed blood loss is another important cause. Experts point to conditions such as ulcers and bleeding piles as examples, while gastrointestinal blood loss can continue without obvious visible bleeding.In such situations, ferritin may fall while haemoglobin remains normal for months. This makes a low ferritin an important finding. What can tiredness sayIron deficiency and iron-deficiency anaemia can produce symptoms that are often vague and overlap with many other conditions. Headache, body and muscle aches, itching, episodes of blackout, ringing in the ears and breathlessness are among symptoms that may occur. Persistent tiredness, weakness, hair loss and poor concentration should prompt evaluation when they do not improve with adequate rest, particularly in people who have risk factors for iron deficiency.However, these symptoms are not specific to iron deficiency. This is why symptoms alone should not be used to decide whether iron supplements are needed. A complete blood count is generally an important starting point. Ferritin and other iron parameters can then help determine whether depleted iron stores are contributing to the problem.Causes of low ferritinFinding a low ferritin is only part of the evaluation. The more important question is why the iron stores have fallen.“Iron deficiency is a symptom of something else, not a disease on its own,” Dr. Thomas says. Treating the deficiency without addressing its cause can allow the problem to recur.Experts caution against starting iron tablets simply because a report shows a low ferritin. Treatment commonly continues for several months, including after haemoglobin improves, to replenish iron stores, but the dose and duration depend on the cause and severity of the deficiency.Seeking diagnosisThe widespread availability of iron supplements can make self-treatment tempting, particularly when symptoms such as fatigue or hair loss are attributed to low iron.But unnecessary supplementation can cause nausea, constipation and abdominal discomfort. More importantly, it can delay the diagnosis of the underlying reason for iron loss. Excessive iron accumulation can also be harmful, particularly in people with disorders that cause increased iron absorption.The message, experts say, is not to panic over an isolated ferritin value, but neither should a low ferritin be ignored simply because the haemoglobin is normal. Dr. Thomas says medical advice is therefore important to determine whether iron deficiency is actually present, identify its cause and decide on the appropriate treatment and duration.