6 Causes of Iron Deficiency in Men Doctors Check Before Prescribing Iron

Men do not menstruate, so when a man turns up with low iron, a doctor's first instinct is not dietary. The body loses iron in only a few ways: through blood, through impaired absorption, or through demand that outpaces supply. In men, the first two dominate the list. A supplement prescribed before finding the source treats the number, not the problem, and in some cases delays a diagnosis that matters.

This is the cause doctors rule out first, because it is the most common and the one that cannot wait. A slow bleed anywhere from the oesophagus to the colon, a peptic ulcer, erosive gastritis, a polyp, haemorrhoids, or in older men, colorectal cancer, can drain iron steadily without producing obvious symptoms. The stool may not look visibly bloody. ICMR data on colorectal cancer trends in India show rising incidence in men under 50, which is part of why gastroenterology referral happens early in the workup rather than after a trial of supplements. If a man's iron keeps falling despite supplementation, a gastroscopy or colonoscopy is the next step, not a higher dose.

Iron from food is absorbed in the duodenum and upper jejunum. When that lining is damaged or inflamed, absorption drops even when dietary intake is adequate. Coeliac disease is the most common structural cause in this category; it is underdiagnosed in Indian men partly because the classic presentation of diarrhoea and weight loss is absent in many adults. H. pylori infection, which has high prevalence across India, reduces gastric acid and impairs the conversion of ferric to ferrous iron, making absorption less efficient. A man who eats iron-rich food and still runs low is worth testing for both.

Non-steroidal anti-inflammatory drugs are taken routinely by men managing joint pain, back pain, and sports injuries, often without a prescription and often for months at a time. NSAIDs damage the gastric mucosa and can cause chronic microbleeding that is invisible without investigation. Low-dose aspirin taken for cardiovascular protection has the same effect at a smaller scale. The blood loss is not dramatic enough to cause symptoms on its own, but over months it depletes iron stores. A doctor asking about iron deficiency will ask about analgesic use specifically, not just alcohol and diet.

Each whole blood donation removes roughly 200 to 250 milligrams of iron. For most donors, the body replenishes this between donations. For men who donate every three months at the minimum interval, or who have a diet low in haem iron, the replenishment does not fully keep pace. The National Blood Transfusion Council of India recommends haemoglobin screening before each donation, but ferritin, the storage form of iron, is not routinely checked. A man who donates regularly and presents with fatigue is worth checking for depleted stores even if his haemoglobin is borderline acceptable.

Endurance athletes and men in heavy physical training have higher iron turnover for several reasons: foot-strike haemolysis (the mechanical destruction of red blood cells during running), iron lost in sweat, and increased red blood cell production driven by training load. This is sometimes called sports anaemia, though it is more precisely a dilutional effect combined with higher demand. A recreational runner doing moderate distances is unlikely to deplete iron this way. A man training for a marathon or doing two-a-day sessions on a vegetarian diet is at genuine risk. The fix involves dietary adjustment, increasing non-haem iron intake alongside vitamin C to improve absorption, not just supplementation.

When red blood cells break down inside blood vessels rather than in the spleen, the haemoglobin released is filtered through the kidneys and iron is lost in urine. This is uncommon, but doctors look for it in men with unexplained iron deficiency who have no GI source and no absorption problem. Paroxysmal nocturnal haemoglobinuria is the textbook example; mechanical heart valves can cause a milder version. Urine that is dark, especially in the morning, alongside iron deficiency is a prompt for further investigation rather than a prescription.

Iron deficiency in a man is a finding that needs a cause, not just a correction. The six sources above are what a thorough workup covers before a supplement is written, because replacing iron without finding where it went is, at best, a temporary fix and, at worst, a reason a treatable condition goes undetected for longer than it should.