Feeling tired is one of the most common reasons people look into blood tests, and anaemia is one of the things a doctor will often want to rule in or out. The first step is usually a full blood count. But a full blood count mainly answers whether haemoglobin is low. It does not always say why. That is where a broader anaemia blood test comes in.
This guide explains what the Full Blood Count measures, what the Anaemia Profile adds, and when a wider look tends to be useful.
What anaemia means
The NHS describes anaemia as having fewer red blood cells than normal, or less haemoglobin in each red blood cell. Haemoglobin is the substance red cells use to carry oxygen around the body. When there is less of it, people may notice tiredness and lack of energy, shortness of breath, noticeable heartbeats, paler skin or headaches. Many other things can cause the same feelings, which is why a blood test is useful.
Iron deficiency is the most common cause of anaemia, according to the NHS, and is one of the most common nutritional problems worldwide (Pasricha et al., 2021). Lack of vitamin B12 or folate is another well-known cause. Long-term inflammation, other medical conditions and inherited differences in haemoglobin can also play a part (Camaschella, 2015).
The Full Blood Count
The Full Blood Count (with 5 part White Cell Differential) is the classic starting point. LML describes it as a measure of the main components of blood: red cells, white cells and platelets. The red cell part includes:
- Haemoglobin: the oxygen-carrying protein.
- Red cell count and haematocrit: how many red cells there are and how much of the blood volume they take up.
- Mean cell volume (MCV): the average size of the red cells. Small cells point one way, often towards iron; large cells point another, often towards B12 or folate.
- Mean cell haemoglobin, mean cell haemoglobin concentration and red cell distribution width: more detail on how much haemoglobin each cell holds and how much the cells vary.
It also reports the white cell count with five types of white cell, and the platelet count. The NHS notes that a GP will usually start with a full blood count when anaemia is suspected.
What the Anaemia Profile adds
The Anaemia Profile contains all the red cell, white cell and platelet measures of a blood count, plus the tests most often used to explain a low result. LML lists 17 markers in total. The additions fall into two groups.
Iron studies
- Ferritin: the body's iron store.
- Iron: what is circulating at the moment.
- Transferrin saturation, total iron-binding capacity and unsaturated iron-binding capacity: how much iron the blood is carrying and how much more it could carry.
British guidance on iron deficiency anaemia in adults describes ferritin as the most useful single marker of iron stores, while noting that inflammation can raise it and make it harder to read (Snook et al., 2021).
Vitamin B12 and folate
Both are needed to make healthy red blood cells. The NHS explains that a lack of either can lead the body to produce abnormally large red cells that do not work properly.
LML describes the Anaemia Profile as a test that helps work out the underlying cause of anaemia, such as iron deficiency, vitamin deficiencies, chronic disease or inherited conditions, and to guide treatment and follow-up.
Why women are often advised to look at this
Iron needs are higher during the reproductive years. LML notes that menstrual bleeding and pregnancy increase iron demand, and the NHS lists blood loss and pregnancy among the common reasons for iron deficiency anaemia. Heavy periods are one of the situations in which a check is often discussed. Iron deficiency can also happen without anaemia, which is why looking at ferritin as well as haemoglobin can be informative (Pasricha et al., 2021).
