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Recurrent iron deficiency: finding the real cause | CION Cancer Clinics
When iron deficiency keeps coming back, the reason you lost iron is usually still there. Blood may still be leaking from heavy periods or the gut, your gut may not be absorbing iron, or treatment stopped before your reserve was full. More tablets alone rarely settle it. This page explains the usual causes, the tests that trace them, the signs that cannot wait and what to ask your doctor. At CION Cancer Clinics, our haematologist cares for anaemia, bleeding, clotting and inherited blood disorders, with ArogyaSri, CGHS and cashless insurance accepted.
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Medically reviewed by Dr. Basudev PokhrelConsultant Haematologist · last reviewed September 2026, next review due September 2027
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On this page
The short answer
Why does my iron keep dropping after treatment?
Iron that keeps falling usually means the reason you lost it is still there. Tablets or an infusion refill the tank, but if blood is still leaking out, or your gut is not taking iron in, the level drops again within months.
Treatment refills iron, it does not find the leak
Iron treatment corrects the shortage. It does not explain it. Many people are given a course of tablets, feel better, stop, and are back at the same report a year later. Each round is treated as a new problem, when it is the same problem that was never traced.
Sometimes the course simply ended too early
Haemoglobin, the red pigment that carries oxygen, often rises first. Your iron reserve, measured as ferritin, takes longer to fill. If treatment stops as soon as haemoglobin looks normal, the reserve is still empty and the next small loss tips you back. Your doctor decides how long treatment runs. Do not stop or change it on your own.
Who needs a proper search for the cause
Anyone whose low iron has come back more than once. Men, and women after their periods have stopped, need it even the first time, because the gut is the usual place blood is being lost.
This page explains the common causes. It cannot tell you which one is yours. That needs your history, an examination and tests.The usual suspects
Where is the iron going?
Almost every case of returning low iron fits one of four patterns. More than one can be at work in the same person.
Blood lost through periods
The most common cause in women before menopause. Periods that feel normal to you may still be heavy enough to drain iron every month.
Clues
- Clots, or changing pads through the night
- Periods lasting longer than a week
Slow bleeding from the gut
Ulcers, piles, pain medicines that irritate the stomach, polyps and sometimes a growth in the bowel. The loss is often too small to see in the stool.
This is why doctors ask for an endoscopy or colonoscopy, a camera test of the food pipe, stomach or bowel.The gut is not absorbing iron
Coeliac disease, a reaction to wheat gluten, damages the lining that takes in iron. So can a stomach infection called H. pylori, stomach surgery, and long use of acid-reducing medicines.
Needs outrun what you eat
Pregnancy, a growth spurt, frequent blood donation and a vegetarian diet built around tea with meals can all leave too little iron coming in.
Worth knowing
- Diet alone is rarely the whole story in adult men
Not sure whether this applies to you?
Ask an oncologistHow it is worked out
How will a doctor look for the cause?
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A careful history
Expect questions about periods, stool colour, pain medicines, acid tablets, diet, blood donation and family history of bowel problems or coeliac disease. Bring every old blood report you have, so the pattern over time can be seen.
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Blood tests beyond haemoglobin
Ferritin and iron studies confirm the shortage. A coeliac antibody test, kidney and liver tests and sometimes a vitamin B12 and folate check look for what sits behind it.
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Stool and urine checks
A stool test can pick up hidden blood or H. pylori. A urine test looks for blood that is not visible.
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A look inside, when needed
Men, women past menopause, and anyone with gut symptoms are usually offered an endoscopy and colonoscopy. Women with heavy periods may see a gynaecologist first.
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A plan that treats both
Iron is replaced, by mouth or by drip, while the cause is treated. Repeat tests later show whether the level is holding.
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Signs that should not wait for a routine appointment
If you pass black, tarry stools or bright red blood, vomit blood, or feel faint and breathless at rest, go to the nearest emergency department today or call 108. See a doctor within days, not months, if low iron comes with weight loss you cannot explain, a change in bowel habit, or food sticking when you swallow. Do not keep treating it with tablets alone.
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Commonly believed
What do families often get wrong about low iron?
"It is just weakness. A tonic will fix it."
Low iron is a sign, not a diagnosis. A tonic may lift the number for a while, but it does nothing about the blood being lost or the gut not absorbing. The report comes back looking the same.
"My haemoglobin is normal now, so I am done."
Haemoglobin recovers before the iron reserve does. Ask your doctor whether your ferritin has been checked before treatment is stopped, and when it will be checked again.
"A camera test is only for people with cancer."
Most endoscopies find something ordinary, like an ulcer, inflammation or piles, or nothing at all. The test is done so a serious cause is not missed, not because one is expected.
"Eating more greens will stop it coming back."
Food helps, and it matters for vegetarians. But if iron is being lost faster than any diet can replace it, eating more will not keep up. The cause still has to be found.
On your report
What do the words on my blood report mean?
- Ferritin
- A measure of your iron reserve. Low ferritin means the store is running empty. Infection or inflammation can push it up and hide a shortage.
- MCV
- The average size of your red cells. Long-standing low iron makes them small, so the MCV falls.
- Transferrin saturation
- How much of the iron-carrying protein in your blood is loaded with iron. Low values point to too little iron reaching the marrow.
- tTG antibody
- A blood test that screens for coeliac disease. You need to be eating wheat for it to be accurate.
- Occult blood
- Blood in the stool that you cannot see. A positive result means the gut needs a closer look.
Reference ranges differ between laboratories. A single result is read alongside your symptoms and repeat tests.
Being straight with you
What should I do if it has come back again?
Ask for the cause, not only another course of iron. Gather every report you have into date order. A doctor who can see the level fall, rise and fall again learns far more than one who sees a single result.
Questions worth asking
What do you think is causing my iron to fall? Has my ferritin been checked, and when will it be checked again? Do I need a coeliac test, a stool test or a camera test? Should I see a gynaecologist or a gut specialist? How long should my current treatment continue?
When a haematologist helps
Most returning low iron is sorted out by a physician, gynaecologist or gut specialist. A haematologist, a doctor for blood disorders, is useful when tablets have not worked, when the blood count shows other changes, or when the cause is still unclear after the usual tests. At CION, the haematology team led by Dr. Basudev Pokhrel reviews the reports, coordinates the tests you need with the right specialists and discusses complex cases at a tumour board.
What this page cannot tell you
It cannot tell you whether your cause is simple or serious. Only tests can. It also cannot set how much iron you need or for how long.
Questions we are asked
Common questions about low iron that keeps coming back
Why did my iron drop again after I finished the tablets?
Usually because the cause is still active, or because treatment stopped before your reserve was full. Haemoglobin can look normal while ferritin is still low. Show your doctor both results, old and new, and ask whether the cause has been looked for. Do not restart or extend tablets on your own.
Could it be cancer?
Sometimes a growth in the stomach or bowel causes slow bleeding, which is why tests are advised, especially for men and older women. Far more often the cause is periods, an ulcer, piles, coeliac disease or diet. The tests exist to find the answer, so the worry does not have to rest on guesswork.
Is an endoscopy or colonoscopy really needed?
For men and women past menopause with low iron, doctors usually recommend both, even without stomach symptoms, because hidden bleeding from the gut is common and often silent. For younger women with heavy periods, it depends on your symptoms and family history. Ask your doctor to explain why it is or is not advised.
Can my acid tablets be the reason?
Long use of acid-reducing medicines can lower how much iron you absorb, because stomach acid helps take iron in. That does not mean you should stop them. They may be protecting you from an ulcer. Tell your doctor you take them and let them weigh the balance.
I am vegetarian. Is that enough to explain it?
It can contribute, especially with tea or coffee taken alongside meals. But a vegetarian diet on its own rarely explains iron that keeps falling despite treatment. Your doctor will still want to rule out blood loss and poor absorption before putting it down to diet.
Would an iron drip stop it coming back?
A drip refills iron faster, and it helps when tablets are not absorbed or not tolerated. It does not fix the reason iron is being lost. Without treating the cause, the level can fall again after a drip just as it does after tablets. Your doctor decides whether it suits you.
How often should my iron be rechecked?
That depends on the cause, how low you were and how you are being treated, so your doctor sets it. What matters is that a recheck is planned, rather than waiting until the tiredness returns. Ask for the date of your next test before you leave the appointment.
Which doctor should I see first?
Start with a general physician, who can order the first tests and refer you on. Women with heavy periods may go to a gynaecologist. If tablets are not working, other blood counts are abnormal, or no cause turns up, ask for a haematologist's opinion. Take all your old reports with you.
Your Haematologist
Meet CION's haematologist. One specialist for your blood report and your plan.
Dr. Basudev Pokhrel reviews blood counts, transfusion needs and blood disorders, and works with the CION tumour board on blood cancers.
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Sources
- NHS — Iron deficiency
- NICE — Clinical Knowledge Summaries: iron deficiency
- NHLBI — Iron deficiency
- American Society of Hematology — Iron deficiency
- National Health Mission — National Health Mission
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Iron Deficiency in Men and Postmenopausal Women: The GI WorkupWhy the gut is checked, and what the tests involveHeavy Periods and Chronic Iron LossThe most common hidden drain in womenHow Long Iron Treatment Takes to WorkWhy stopping early lets the level fall againIV Iron: When Tablets Are Not EnoughWhen a drip makes senseIron DeficiencyThe full guide to low iron
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Low iron again, and no clear reason?
Share your old and new blood reports with us. CION's haematology team will read the pattern and tell you which tests are worth doing next. One helpline serves every CION centre.