Heavy periods: causes and when to test

You plan your day around your period: no light-coloured clothes, a spare set in your bag, and still you leak through around lunchtime. Many women do not know whether their period is actually heavy, simply because they have nothing to compare it to. You only know your own experience. Yet the difference matters, because heavy blood loss can slowly deplete your iron stores.

My take: with a heavy period, fatigue is not a separate problem but often the first sign that your iron is dropping. Two blood values usually give the most insight here: ferritin and hemoglobin. Below you read when a period is truly heavy, what the causes can be and which values give insight.

When is a period heavy?

A period is called heavy when you lose a lot of blood or when it limits your daily life. A handy guide is how often you have to change your protection and whether you leak through, even with double protection. The Dutch GP guideline on vaginal blood loss (NHG) names large clots and a period lasting longer than seven days as signs that can belong to it.

• You change your protection every hour or more often
• You leak through, even with double protection or at night
• You lose large clots
• Your period lasts longer than seven days
• You feel tired or dizzy around your period

If you recognise this every month, it can be worth looking further, because prolonged heavy blood loss can deplete your iron.

What can cause a heavy period?

The cause ranges from hormonal fluctuations to abnormalities in the uterus, such as fibroids or polyps. Sometimes a clotting problem plays a part. Often there is no clear abnormality and it is a hormonal imbalance. Which cause fits you depends on your age and your other complaints.

Unsure about the broader context of your cycle? Then read our pillar on irregular periods and which hormones to test. This table is a tool, not a diagnosis.

Why iron is so important with heavy blood loss

With every period you lose iron, and with a heavy period that loss can be greater than you replenish through food. So your iron stores can slowly drop, often without you noticing immediately. Complaints such as fatigue, shortness of breath or pale skin can come later. The Netherlands Nutrition Centre (Voedingscentrum) points out that women who menstruate have a higher iron need than men.

A low iron can already cause complaints before there is actual anemia. Also read our article on iron deficiency without anemia and what a low ferritin means. Mainly feeling tired and drained? Then read which blood values to test for fatigue.

Which blood values give insight?

With a heavy period you mainly look at two values. Ferritin shows how large your iron stores are, and hemoglobin shows whether there is already anemia. Together they give a picture of the impact of your blood loss.

• Ferritin, your iron stores, which often drop first
• Hemoglobin, which shows whether there is anemia

The Iron Status panel shows your ferritin, among others. If your cycle is also erratic, the Women's Hormones panel can help. An abnormal result is always something to discuss with your GP.

When do you go to the GP?

Go to the GP if your period limits your daily life, if you leak through despite double protection, or if you have signs of anemia such as persistent fatigue or dizziness. Newly arisen heavy blood loss is also a reason to have it assessed.

• Your blood loss limits your work, sport or social life
• You have persistent fatigue, dizziness or shortness of breath
• Your period has suddenly become much heavier
• You have blood loss between your periods

A blood test gives insight into the consequences, but the cause of the blood loss is assessed by the GP. So always discuss your result with a doctor.

Frequently asked questions

How much blood is too much during a period?

An exact amount is hard to measure in practice. A good guide is whether you leak through, lose large clots or whether it limits your daily life. If you recognise that, it can be worth having it assessed.

Can a heavy period cause iron deficiency?

Yes, it can. With heavy blood loss your iron stores can slowly drop, sometimes without you noticing immediately. That is why it can be worth having your ferritin and hemoglobin checked.

Which blood test do I do for a heavy period?

You often start with ferritin and hemoglobin to map the consequences for your iron. If your cycle is also erratic, a hormone test can give additional insight. Discuss with your GP what suits you.

Sources

• NHG guideline on vaginal blood loss, Dutch College of General Practitioners. Available via richtlijnen.nhg.org.
• Thuisarts.nl, I lose a lot of blood during my period, Dutch College of General Practitioners. Available via thuisarts.nl.
• Netherlands Nutrition Centre (Voedingscentrum), Iron. Available via voedingscentrum.nl.

Every blood test result via Lunara receives a professional review by a BIG-registered doctor. For treatment decisions, discuss your results with your GP.