Iron Deficiency in Men: The Symptom That Should Never Be Ignored

Iron deficiency is widely regarded as a women's health issue, and in terms of raw numbers that is fair. Menstruation and pregnancy make it far more common in women, and the medical conversation has developed accordingly. The consequence is that when a man turns up with low iron, it is sometimes treated the same way, with a supplement and a follow-up in three months.

That is a mistake. An adult man loses roughly one milligram of iron a day through shed skin and gut cells, and a normal diet replaces it comfortably. For a man to become iron deficient, something has to be either removing iron faster than that or preventing him from absorbing it. Iron deficiency in a man is a symptom with a cause, and finding the cause is the actual medicine.

What iron does

Most of the body's iron sits inside haemoglobin, the protein in red blood cells that binds oxygen in the lungs and releases it in tissues. A further portion sits in myoglobin in muscle, and in the enzymes that run the mitochondrial electron transport chain, which is how cells generate energy.

This is why iron deficiency causes fatigue before it causes anaemia. Once storage iron is depleted but haemoglobin is still normal, the enzymes that depend on iron are already under-supplied. You can feel unwell with a perfectly normal full blood count, which is precisely why iron studies and not just haemoglobin need to be measured.

Symptoms

• Fatigue and low endurance disproportionate to sleep and workload
• Breathlessness and a racing heart on exertion that was previously easy
• Reduced exercise performance, longer recovery, plateaus in training
• Poor concentration and mental fog
• Pale skin and conjunctivae, though this is unreliable and appears late
• Cold hands and feet
• Brittle nails, sometimes spoon-shaped in prolonged deficiency
• Hair shedding
• Restless legs at night, a genuinely common and under-recognised sign
• Pica, an urge to chew ice or non-food items, uncommon but distinctive

The overlap with low testosterone, thyroid dysfunction, sleep apnoea, depression and simple overwork is almost complete, which is why a fatigue workup needs bloods rather than guesswork.

Why a man becomes iron deficient

Blood loss from the gastrointestinal tract

This is the first thing to exclude, and the reason iron deficiency in a man is taken seriously. Chronic slow bleeding from the gut is often invisible in the stool, and the list of causes includes peptic ulcer disease, gastritis, oesophagitis, angiodysplasia, coeliac disease, inflammatory bowel disease, haemorrhoids, polyps and colorectal cancer.

Colorectal cancer is among the most common cancers in Singaporean men, and iron deficiency anaemia is one of its classic presenting features. It frequently produces no bowel symptoms at all in its earlier stages. This is the single most important reason not to simply prescribe iron and move on. In a man over forty with unexplained iron deficiency, an endoscopic evaluation of the upper and lower gastrointestinal tract is usually the appropriate next step, and finding nothing is a good outcome, not a wasted investigation.

Impaired absorption

Iron is absorbed in the duodenum and requires an acidic environment. Long-term proton pump inhibitor use for reflux, which is extremely common, reduces absorption measurably. Coeliac disease damages the absorptive surface and can present with iron deficiency long before any bowel symptoms. Helicobacter pylori infection, previous gastric surgery and bariatric procedures all interfere.

Inadequate intake

Diet alone rarely causes deficiency in a man eating an unrestricted diet, because haem iron from meat and fish is well absorbed. It becomes relevant in strict vegetarian and vegan diets, where non-haem plant iron is absorbed far less efficiently and absorption is further inhibited by phytates in grains and legumes, calcium, and the tannins in tea and coffee taken with meals.

Increased demand or loss

Endurance athletes lose iron through gastrointestinal microbleeding, sweat, and a phenomenon called foot-strike haemolysis. Regular blood donors deplete stores steadily. Chronic kidney disease and heart failure both alter iron handling.

Getting the right tests

A haemoglobin level alone is not sufficient, because it only becomes abnormal after stores are exhausted. The useful panel is:

Test	What it tells you
Full blood count	Haemoglobin, and red cell size which falls in iron deficiency
Ferritin	Storage iron, the single most useful marker
Transferrin saturation	How much iron is available for use right now
Serum iron and TIBC	Supporting detail for interpretation
CRP	Detects inflammation, which falsely raises ferritin

Ferritin below 30 micrograms per litre generally indicates deficiency, and below 15 is unequivocal. The important caveat is that ferritin is an acute phase reactant, so infection, inflammation, obesity, liver disease and recent hard training can raise it into the normal range while stores are genuinely empty. When CRP is elevated, a ferritin up to around 100 may still be consistent with deficiency, and transferrin saturation below sixteen percent supports the diagnosis.

Where deficiency is confirmed in a man, further investigation typically includes coeliac serology, testing for Helicobacter pylori, faecal occult blood testing and, in most adults, referral for endoscopy.

Treatment

Oral iron

Oral iron salts remain first line and are inexpensive. The practice has changed in one important respect: alternate-day dosing is now generally preferred to multiple daily doses. Taking iron raises hepcidin, a hormone that blocks further absorption for around twenty-four hours, so a single dose every other day is absorbed more efficiently than the same total spread across each day, and causes fewer side effects.

Absorption improves when taken on an empty stomach with vitamin C, and is reduced by tea, coffee, calcium, dairy and antacids. Constipation, nausea, abdominal discomfort and dark stools are the usual complaints, and are the main reason people abandon treatment. Reducing frequency rather than stopping is usually the better response.

Replenishing stores, as opposed to correcting haemoglobin, takes three to six months. Stopping as soon as you feel better leaves the tank empty and guarantees a recurrence.

Intravenous iron

IV iron is appropriate where oral iron is not tolerated, not absorbed, or where the deficiency is severe and needs correcting quickly. Modern preparations allow large doses in one or two visits with a good safety record, though they require administration in a clinical setting with monitoring.

Diet

Dietary change alone will not correct an established deficiency, but it supports maintenance. Haem iron from red meat, liver, poultry and fish is absorbed several times more efficiently than plant iron. For those eating little or no meat, pairing lentils, tofu, dark leafy greens and fortified cereals with a source of vitamin C at the same meal, and separating tea and coffee from meals by an hour, makes a measurable difference.

The point worth repeating

Correcting the number is the easy half. In a man, the question that matters is why the iron went missing, and that question has an answer worth finding. Treating the deficiency without investigating the cause can mask a slowly bleeding lesion for months while the patient feels progressively better on supplements.

Related reading: vitamin D deficiency in Singapore, health screening in Singapore, and the big three: blood pressure, cholesterol and diabetes.

Ferritin vs full blood count: reading the two together

Doctors are sometimes asked why a man needs both a full blood count and a ferritin when either alone seems to answer the question of "do I have anaemia". The two tests measure different things and, used together, tell a story that neither can tell alone.

The full blood count reports haemoglobin and red cell indices. In iron deficiency, red cells become small (microcytic, reflected in a low mean corpuscular volume) and pale (hypochromic, reflected in a low mean corpuscular haemoglobin) before haemoglobin itself falls. A falling mean corpuscular volume in a man with a previously normal blood count, even while haemoglobin sits within range, is an early warning that iron stores are being drawn down and is worth chasing with a ferritin rather than waiting for anaemia to develop outright.

Ferritin reflects the size of the storage pool, essentially how much iron is banked for future use. It is the more sensitive marker and falls well before red cell changes appear, which is why a man can feel fatigued with an entirely normal full blood count and a ferritin already in single figures. The complication, mentioned above, is that ferritin also rises with inflammation, so a normal or high ferritin in a man with an active infection, recent surgery, obesity or heavy alcohol use does not reliably exclude deficiency. This is the scenario where transferrin saturation, serum iron and TIBC earn their place on the request form, because they behave differently to inflammation and give a truer picture when ferritin is ambiguous.

In practice, the two tests are read side by side. A low mean corpuscular volume with a low ferritin confirms iron deficiency without argument. A normal full blood count with a low ferritin identifies deficiency before it becomes anaemia, which is the point at which correcting it is easiest and at which finding the underlying cause matters most, since the man is still otherwise well. A low mean corpuscular volume with a normal or high ferritin points away from iron deficiency and towards other causes of microcytosis, such as thalassaemia trait, which is relatively common in Singapore's population and worth distinguishing because giving iron to a man with thalassaemia trait rather than deficiency achieves nothing and delays the correct explanation.

Causes that always warrant a gastrointestinal work-up

Not every man with iron deficiency needs the same intensity of investigation, but certain patterns should never be managed with a supplement alone regardless of how well the man otherwise feels.

Any man over the age of forty with newly confirmed iron deficiency and no other obvious explanation, such as a strict vegetarian diet or regular blood donation, should be referred for assessment of the gastrointestinal tract. This typically means gastroscopy and colonoscopy, because the two most common serious causes, peptic ulcer disease and colorectal neoplasia, can each occur without producing any bowel symptoms whatsoever until late.

A change in bowel habit, rectal bleeding of any amount, unexplained weight loss, or a family history of colorectal cancer in a first-degree relative all raise the priority of investigation and should not be deferred while a trial of oral iron is attempted. Reflux symptoms alongside iron deficiency raise the possibility of oesophagitis or, less commonly, oesophageal pathology, and long-term proton pump inhibitor use should be documented as a contributing factor rather than assumed to be the sole explanation.

A younger man with iron deficiency and gastrointestinal symptoms such as bloating, altered bowel habit or a family history of coeliac disease should have coeliac serology checked before or alongside endoscopic referral, since coeliac disease can present with iron deficiency as its only feature for years.

The underlying principle is the same one that runs through this whole article: the finding itself is not dangerous, but treating it without asking why it is there can allow a genuinely serious cause to progress unchecked while the blood count looks reassuring on paper.

Frequently Asked Questions

Q: Can men get iron deficiency without any obvious bleeding?

A: Yes, and that is the usual pattern. Chronic gastrointestinal blood loss is often microscopic and invisible in the stool, coming from ulcers, gastritis, polyps or bowel cancer without any visible change. Absorption problems from long-term acid suppression or undiagnosed coeliac disease are also common and produce no symptoms other than the deficiency itself.

Q: My haemoglobin is normal. Can I still be iron deficient?

A: Absolutely, and this is one of the most frequently missed findings. Storage iron depletes long before haemoglobin falls, so you can have a completely normal full blood count while your ferritin is very low and you feel exhausted. Diagnosing this requires ferritin and transferrin saturation, not just a full blood count.

Q: Do I need a colonoscopy if my iron is low?

A: In an adult man with unexplained iron deficiency, investigating the gastrointestinal tract is usually recommended, and that commonly means both upper endoscopy and colonoscopy. Colorectal cancer is a common cancer in Singaporean men and can present with iron deficiency before any bowel symptoms. Your doctor will weigh your age, history and severity, but declining investigation because you feel well is the wrong call.

Q: How long should I take iron supplements?

A: Typically three to six months after your haemoglobin normalises, because correcting the blood count happens well before storage iron is replenished. Stopping as soon as you feel better is the most common reason for recurrence. Treatment should be followed by a repeat ferritin to confirm the stores have actually refilled.

Q: Why does iron make me constipated, and what can I do?

A: Unabsorbed iron irritates the gut and slows transit. Alternate-day dosing rather than daily dosing improves absorption and reduces side effects considerably, and taking the dose with vitamin C rather than food maintains absorption. Increased fluid and fibre help. If oral iron remains intolerable, intravenous iron is an effective alternative.

Q: Can too much iron be harmful?

A: Yes. Iron overload damages the liver, heart and pancreas, and some people carry genetic haemochromatosis which causes it without any supplementation. This is why iron should be taken on the basis of a measured deficiency rather than as a general tonic, and why levels should be rechecked rather than supplements continued indefinitely.

Book a nutritional and vitamin panel at our Orchard clinic or speak to a doctor about unexplained fatigue.