Iron deficiency in perimenopause: the fatigue nobody investigates

The fatigue that looks like nothing

This is not the tiredness of a bad night. It is a background fatigue that does not yield to rest, with breathlessness on the stairs that was not there last year, difficulty holding a conversation at the end of the day, hair falling out more than before, sometimes legs that will not stay still in the evening.

Many women describe this in their fifties and attribute it to menopause, to work, to the mental load. All these explanations can be true. One is often missing, simple to look for and easy to correct : a lack of iron.

One publication worked precisely on framing this problem in women with heavy menstrual bleeding⁶, and another showed its measurable impact on quality of life⁵.

Being short of iron without being anemic

This is the point everyone should know, and it explains most missed diagnoses.

The body keeps its iron in two places : the iron circulating in the red blood cells, and the iron held in reserve. When intake no longer offsets losses, the stores empty first. Haemoglobin, for its part, stays normal, sometimes for months, sometimes for years.

Throughout that period, the blood count is reassuring and the fatigue is real. This picture has a name, iron deficiency without anemia, and a piece of work was devoted to it in young women with heavy periods, describing it as common and under-recognized².

Practical consequence : if only a blood count is requested, it can be missed completely. It is ferritin that reflects the stores.

Why perimenopause is the risk period

Cycles go out of order, and some women see their periods become clearly heavier or longer. Each cycle then draws more iron, and diet does not keep up.

The relationship between heavy periods, iron deficiency and iron deficiency anemia is well described¹. It sets in insidiously : losses increase gradually, the woman gets used to it, and nobody does the arithmetic.

Two concrete markers to judge by : having to change protection every hour or less for several hours, or bleeding that lasts more than seven days. Our article on heavy periods in perimenopause details what must be investigated.

Which tests to ask for, and how to read them

Three measurements are usually enough :

• a complete blood count, for haemoglobin and the size of the red blood cells ;
• ferritin, the reflection of the stores ;
• CRP, because inflammation artificially raises ferritin and can mask a deficiency.

Transferrin saturation is sometimes added when interpretation is difficult.

The thresholds vary between guidelines and between laboratories, and this is a real source of confusion : a review of clinical guidelines devoted to women with heavy menstrual bleeding documented precisely this heterogeneity⁴. A clinical opinion has moreover proposed optimizing diagnosis and treatment in women of reproductive age³.

What to take from it : a ferritin "in the low normal range" accompanied by symptoms is not a result to file away. Ask for the actual figure, not just the word "normal".

After 50, a precaution that is not negotiable

This is the most important passage of this article, and it fits in one sentence : in a woman whose periods have stopped, iron deficiency makes it necessary to look for digestive bleeding.

Automatically attributing it to "somewhat heavy periods" is the shortcut that delays some colorectal cancer diagnoses. Iron deficiency anemia discovered after menopause justifies a digestive investigation, unless there is an obvious and documented explanation.

This is not a reason to be alarmed : the great majority of these investigations find nothing serious. It is a reason not to skip them.

How it is corrected, and why it takes time

Oral iron remains the first-line treatment in most situations. Two things make it more effective : taking it away from tea, coffee and calcium, and knowing that taking it every other day is currently discussed as a way of improving absorption while reducing digestive effects. These arrangements are decided with your doctor.

Tolerance is the real obstacle : nausea, constipation, black stools. Many women give up after ten days and conclude that "iron does not agree with them".

When oral iron is not enough or is not tolerated, intravenous iron exists. A randomized trial compared two forms (ferric carboxymaltose and iron sucrose) in perimenopausal women with iron deficiency anemia linked to heavy menstrual bleeding⁷. It is a hospital or clinic treatment, given under supervision, but it settles in one or two infusions what months of tablets had not corrected.

One last point, often forgotten : rebuilding the stores takes months, well after haemoglobin has come back up. Treatment stopped as soon as the blood count is normal leaves the stores empty, and the fatigue returns.

Do not supplement blindly

Iron is not a harmless supplement. An excess exposes you to overload, and some genetic iron overload diseases are more common than people think. Supplementing "just in case", without testing, is a bad idea.

The logical order is always the same : measure, treat the cause of the bleeding when there is one, correct, then re-check. Our article on dietary supplements comes back to this reflex of supplementing blindly.

In short

If you have been exhausted for months and your periods are heavy, ask for a ferritin, not just a blood count. A lack of iron can exist with a perfectly normal haemoglobin.

And if your periods stopped more than a year ago, iron deficiency is never a conclusion : it is a question that has to be answered.

⚠️ This article is provided for informational and educational purposes only. It does not replace medical advice, diagnosis or treatment. Always consult your doctor or a qualified health professional with any questions about your health.

How we work: our editorial method · Written and verified by Bouchra, editorial lead.