10 February 2022 |

Iron deficiency: when does it become anemia?

carenza di ferro e anemia - ragazza bionda con il braccio teso in attesa di un prelievo di sangue

Iron is an extremely important mineral for our health because it is responsible for so many functions, the most important of which is that of transporting oxygen in the blood. When this element is not present due to an unbalanced diet or increased body needs, there is a risk of developing sideropenia, or rather, iron deficiency anaemia.
So, what are the correct values to be monitored through blood tests and how can we correct a moderate or severe iron deficiency?

The difference between iron deficiency and anaemia

Iron is an essential element for our cells and is crucial in certain metabolic processes in the body, in particular:

  • For the bone marrow to produce new red blood cells;
  • To transport oxygen around the body
  • To promote the synthesis of fats (lipids), sugars (carbohydrates) and genetic material (DNA and RNA).

Iron deficiency is a condition which is characterised by a deficit of this mineral in the body which, if not corrected, leads to actual anaemia. Iron-deficiency anaemia is a condition that occurs when the body is unable to produce enough haemoglobin to ensure proper oxygenation of the body.

How many types of anaemia are there?

Anaemia can be classified according to the underlying cause. The most common forms are:

  • iron-deficiency anaemia, also called sideropenia. This is the most common form of anaemia;
  • sickle cell anaemia, a genetic and hereditary form that causes a sickle shape of the red blood cell;
  • Mediterranean anaemia, a hereditary disease in which red blood cells are destroyed;
  • vitamin deficiency anaemia, particularly vitamin B12 and vitamin C.

Iron deficiency and anaemia in numbers

It is estimated that 25% of the world’s population suffers from anaemia, which is especially prevalent among children and pregnant women. Iron deficiency is undoubtedly the most common cause and is responsible for 50% of all forms of anaemia1.
Several studies have been carried out, finding it to be present in 43% of children under the age of 4. This is why the World Health Organisation (WHO) considers iron deficiency anaemia to be the most common nutritional deficiency in the world.2

Blood values to be monitored in the event of anaemia

In a person with anaemia, the haematological picture is characterised by a reduction in the values of the following parameters: haemoglobin, sideremia, transferrin saturation (Tsat%) and ferritin. However, in order to correctly formulate a diagnosis of anaemia, it is essential to also assess the following parameters: MCH (mean corpuscular haemoglobin content) and MCV (mean red blood cell volume). Let’s take a closer look at what these parameters, which are measured through common blood tests, refer to.

Haemoglobin is the protein most commonly found in the blood. It contains iron, which transports oxygen to the tissues and areas where it is needed. Anaemia occurs when haemoglobin levels are lower than:

Men < 14 g/dL
Women < 13 g/dL
Pregnant women < 12 g/dL
Children < 11,5 g/dL

Table 1: values of haemoglobin in the blood indicating the presence of anaemia

Sideremia is the parameter indicating the amount of circulating iron bound to a specific protein: transferrin. If a deficiency is detected and based on the sex and age of the subject, sideremia is found to be low when its values are below:

Men < 65 µg/dL
Women < 50 µg/dL
Children < 50 µg/dL

Table 2: values defining the minimum concentration of sideremia in the blood

Transferrin saturation (Tsat%) however indicates the percentage of iron bound to this protein; if this is less than 20% it indicates a deficiency.

Ferritin is the ultimate iron storage protein, capable of holding more than 4000 iron ions, and is found mainly in the liver, spleen, bone marrow and, to a small extent, in plasma. It plays an important role in laboratory investigations as its concentration is closely related to iron levels in the body.3 A low concentration of ferritin (<20 µg/L) indicates an iron deficiency, while values above the normal range (>300 µg/L) suggest an inflammatory state of the body, which is why it is also used as an inflammatory marker.

However, when we talk about sideropenia, there are not always obvious haematological changes; in fact, haemoglobin levels may be normal, while those of ferritin and transferrin saturation remain low. If the condition is not rebalanced, sideropenic anaemia may develop.

A differential diagnosis should therefore be made to ascertain whether the clinical condition is a simple deficiency or an established pathological condition such as anaemia. The most frequent symptoms of anaemia are:

  1. Pallor
  2. Feeling weak
  3. Irritability
  4. Dizziness
  5. Fatigue
  6. Cold feet and hands with a tingling sensation
  7. Speeding up of the heartbeat (tachycardia)

What are the consequences of untreated iron deficiency?

When iron deficiency is not corrected and worsens, over time a condition of sideropenic anaemia may develop.

It also increases the risk of contracting infectious diseases: iron plays an important immunomodulating role, as it is directly involved in the formation and maturation of white blood cells, especially lymphocytes, the cells which defend the body against attacks by pathogenic micro-organisms.

At a cognitive level, studies have shown that iron deficiency can affect proper brain function, causing memory problems and limiting learning abilities, to the extent that it is also related to the processes of senile dementia, such as Alzheimer’s.

Furthermore, in elderly people with heart disease such as heart failure, untreated iron deficiency can worsen the clinical picture, reducing functional capacity and quality of life.

In the case of younger people, the lack of adequate iron intake during childhood and, in particular, in the early years can affect growth in terms of both physical and cognitive development.

How to restore normal iron levels in the body through diet: foods rich in iron and the use of supplements

The foods containing the most iron are: liver, offal, seafood, meat in general and horse meat in particular, fish, milk, certain types of green vegetables (especially Brussels sprouts and spinach), legumes (beans), dried fruit (almonds and dried figs in particular) and cocoa.

These foods can be divided into two groups:

  • Foods containing heme (organic): this type of iron is easily absorbed by the body as it is bound to particular proteins (globins) which pass directly into the bloodstream. Heme iron is contained in foods such as meat and fish, particularly in liver, offal and seafood;
  • Foods containing non-heme (inorganic) iron: iron can be found according to its oxidation state as a ferrous ion (bivalent) or as a ferric ion (trivalent). Ferrous iron is soluble, whereas ferric iron is insoluble, so it must be converted into bivalent iron to be absorbed by the intestine. This type of iron is found in vegetables, legumes, eggs, red meat and dairy products.

Only 5% of the iron contained in plant foods is absorbed, while this percentage increases to 10-20% in meat foods. For this reason, those who follow a vegetarian diet, or one that is low in meat, expose their bodies to the risk of developing sideropenia.

This can be remedied by following a diet rich in alternative sources of iron and, where this is not possible or not sufficient, supplementing the normal diet with specific food supplements to correct this deficiency.

In these cases, the supplements in the SiderAL® range, based on Sucrosomial® Iron, help the body to restore normal iron levels, without causing the undesirable effects commonly associated with other more conventional iron salts.



  1. Wawer A.A., Jennings A., Fairweather-Tait S.J., Iron status in the elderly: a review of recent evidence. Mech Ageing Dev. 2018 Oct; 175:55-73.
  2. Bathla S., Arora S., Prevalence and approaches to manage iron deficiency anemia (IDA). Crit Rev Food Sci Nutr 2021:1–14.
  3. Gregory J. Anderson, David M. Frazer, Current understanding of iron homeostasis. The American Journal of Clinical Nutrition, Vol 106. 2017 Dec; 1559–1566.

anemia carenza di ferro