Stores empty, blood count normal
Iron deficiency particularly affects women before menopause. Anaemia is only one of its consequences; impairments can occur before the blood count becomes abnormal. That is how a 2021 review in The Lancet sums it up.
Which value shows it
Ferritin shows how full the stores are. Exactly where the threshold lies is debated. A 2021 study of more than 1,000 young women measured when the body starts absorbing more iron from food: as soon as ferritin falls below about 50 µg/l. The authors interpret this as the beginning of iron deficiency. Other thresholds are set lower – ask which threshold your lab uses and where your value lies.
There is more for athletes in our article on iron, periods and sport (in German).
The most common cause: periods
Periods mean losing iron; that is why the German Nutrition Society recommends 16 mg a day for women before menopause, compared with 11 mg for men. Heavy menstrual bleeding is one of the most important reasons for iron deficiency and is often not taken seriously. How to recognise it is explained in our article on heavy periods.
The Lancet review stresses that the cause should always be looked for; considering a test for coeliac disease is part of this routinely.
Treat – but based on test results
In most cases the first choice is iron taken by mouth. High doses are absorbed less well because the body then reduces absorption. The amount is for your doctor to decide; Rhythmus deliberately gives none.
An analysis of 21 studies from 2022 found that in iron deficiency without anaemia, iron given as an infusion slightly improved physical performance and slightly reduced tiredness. The quality of the evidence was mostly low; quality of life did not differ.