Fibroids (myomas): symptoms, anaemia and what you can test

Fibroids are so common that "abnormality" is almost the wrong word. In an American ultrasound study, by around age 50 nearly 70 percent of white women and more than 80 percent of black women had had one at some point (Baird, 2003). Most women never notice them.

But if they do bother you, they really bother you. Heavy bleeding, a belly that grows fuller, and that tiredness you cannot place.

That last one is where we can add something. Because that tiredness is often written in your blood, even when the fibroid itself is only visible on an ultrasound.

What are fibroids?

Fibroids, also called myomas, are benign lumps of muscle and connective tissue that grow in or on the wall of your uterus. They are hormone sensitive: under the influence of oestrogen they can grow, and after menopause they often shrink. They are benign and do not become cancer.

You can have one, or a handful at once.

Where the lump sits largely determines your complaints. A fibroid pressing into the uterine cavity is more likely to cause heavy bleeding. A fibroid on the outside is more likely to give a pressing feeling or a fuller belly.

It is the third condition in the same family. For the difference with adenomyosis and endometriosis, read our pillar adenomyosis: symptoms, diagnosis and what blood tests add, with a comparison table.

What are the symptoms of a fibroid?

Most fibroids cause no complaints. When they do, heavy and prolonged periods are the best known symptom, often with clots. Alongside that come a pressing feeling or a fuller belly, needing to urinate more often, pain during sex and fatigue. That fatigue usually comes from the blood loss, not from the fibroid itself.

That distinction matters, because it determines what you can do about it.

Look at the right-hand column. Two of the five rows are measurable in your blood, the rest are not. That is the honest answer to the question of what a blood test does for you here.

Why do fibroids cause anaemia?

Fibroids are one of the most common causes of iron deficiency and anaemia in women of reproductive age. With every period you lose more blood than usual, and so more iron. Your body can compensate for a while, but the store slowly drains (Donnez, 2022).

This is exactly the trap I see women fall into too often.

Imagine your Hb is 7.5 mmol/l, neatly within the reference range. Your GP says your blood is fine. But your ferritin, your iron store, may have been below 15 µg/l for months. You are then not anaemic, but you are iron depleted. And you feel it: tired, short-tempered, breathless on the stairs.

So always ask for ferritin, not just Hb. That is the one real piece of advice I will give you.

What can you have tested?

A fibroid is diagnosed with an internal ultrasound, not with blood tests. Blood tests map the consequences: whether the bleeding has affected your iron store and whether anaemia has developed. That is the question a tube of blood can actually answer.

These values are relevant here:

• Ferritin: your iron store, the first value to fall
• Hb and the blood count: show whether anaemia is present
• Thyroid (TSH): an underactive thyroid can worsen heavy bleeding and fatigue

The Anemia panel measures these in one draw. If you want to track your iron store specifically, for example because you already take iron tablets, look at the Iron status.

Further reading: ferritin level and what a low ferritin means and anaemia from heavy periods.

When should you see your GP?

See your GP if your period is so heavy that you have to change every hour, if you lose clots, if you have become tired or breathless, or if your belly grows fuller without a clear reason. An ultrasound then brings clarity quickly, and your blood values tell you what the bleeding has done to you.

Treatment depends on your complaints, not on the size of the fibroid.

Many women with fibroids do not need to do anything. If they do cause complaints, there are various options, from medication that reduces the bleeding to procedures that remove the fibroid (Vannuccini, 2024). Which route fits is something you decide together with your doctor.

Thuisarts.nl describes the options in plain language and the NHG guideline on vaginal bleeding shows which steps your GP usually takes. Useful reading before your appointment.

Frequently asked questions

Are fibroids dangerous?

Fibroids are benign and do not become cancer. They can cause troublesome complaints, especially heavy bleeding, and that can lead to iron deficiency or anaemia. Complaints are therefore the reason to act, not the fibroid in itself.

Can you see a fibroid in your blood?

No. A fibroid is seen on an internal ultrasound. Blood tests do show what the bleeding has done to your iron store and your Hb. Ask for ferritin as well, because that value falls before your Hb does.

Do fibroids disappear after menopause?

They often shrink after menopause, because they are hormone sensitive and oestrogen levels fall. Complaints therefore ease for many women. New bleeding after menopause should always be investigated though, even if you have fibroids.

References

1. Baird DD, et al. High cumulative incidence of uterine leiomyoma in black and white women: ultrasound evidence. American Journal of Obstetrics and Gynecology, 2003. PMID 12548202.
2. Donnez J, et al. Uterine disorders and iron deficiency anemia. Fertility and Sterility, 2022. PMID 36182260.
3. Vannuccini S, et al. The modern management of uterine fibroids-related abnormal uterine bleeding. Fertility and Sterility, 2024. PMID 38723935.
4. NHG. NHG guideline on vaginal bleeding. Dutch College of General Practitioners. Available via richtlijnen.nhg.org.
5. Thuisarts.nl. I have a fibroid in my uterus. Dutch College of General Practitioners. Available via thuisarts.nl.

Every blood test result through Lunara includes a professional assessment by a BIG-registered doctor. For the diagnosis and treatment of a fibroid, discuss your symptoms with your GP or gynaecologist.