serum iron

Generality

Sideremia indicates the amount of iron present in the blood.

More correctly, the sideremia detects the concentration of the so-called "transport" iron, measuring the quantity of the mineral bound to transferrin.

What is transferrin

Transferrin is the protein responsible for transporting iron within the body.

Thanks to transferrin, liver and intestines, iron is distributed - via the bloodstream - to the tissues that need it.

The test is performed with a simple blood sample .

Normally, sideremia levels in an adult organism are around 105 mcg per deciliter of blood (where mcg or µg = micrograms).

The normal values ​​are a little higher in men than in women, and can also vary depending on the age of the subject.

Abnormal sideremia values ​​can report pathological conditions. In particular:

• A Sideremia Bassa can depend on: reduced dietary intake or increased demands (pregnancy and rapid growth in children); excessive blood loss due to bleeding; conditions in which iron is absorbed to a greater extent by tissues (infectious diseases, neoplasms, etc.).
• A Sideremia Alta may depend on : excessive absorption from the intestine; repeated blood transfusions.

What is the Sideremia

Iron is a very important element for the body, since it is essential for the transport of oxygen to the tissues and for the formation of some enzymes.

Iron is a constituent of hemoglobin, which transfers oxygen from the lungs to peripheral tissues via blood, and myoglobin, which performs the same task in muscle tissue

Sideremia indicates the concentration of the "transport" iron present in the blood.

In the blood stream, iron does not circulate freely, but is found partly bound to a carrier protein, called transferrin, partly incorporated into hemoglobin a and partly associated with other minor proteins (such as ferritin ).

Sideremia measures the amount of iron bound to transferrin. Since the latter can exist in a saturated (ie associated with iron) or free form, the sideremia value also provides an indication of the proportion of the iron-bound protein.

What do you measure?

The test measures the sideremia, that is the concentration of iron circulating in the blood, not linked to hemoglobin (the so-called "transport iron"). Based on the measured values, the doctor will evaluate if his levels are normal.

In a healthy adult individual, there are about 3-5 grams of total iron, of which:

• One part is found in red blood cells ( iron bound to hemoglobin );
• A part is stored as a deposit and constitutes the body's reserves ( iron bound to ferritin and hemosiderin );
• One part represents the "transport iron" ( iron bound to transferrin ), which, through the blood, is conveyed by the liver and intestine to the tissues that need it.

In conclusion, since the amount of free iron in the blood is negligible, the sideremia measures, in fact, the iron bound to transferrin.

What does "transport" iron (ferro-transferrin bond) mean?

With respect to the total amount of iron present in the body (estimated at around 4-5 grams and contained above all in the hemoglobin of red blood cells and in myoglobin of muscles), the sideremia value represents a negligible fraction in terms of quantity, but absolutely important on the functional one. The iron carried by transferrin is, in fact, essential for the normal processes of hemoglobin formation, and therefore of the red blood cells.

The iron associated with transferrin comes from various metabolic stations, such as:

• Intestinal mucosa (where it is absorbed);
• Bone marrow (where it is incorporated into red blood cells);
• Liver (where it is stored);
• Spleen (where aged cells are degraded and iron is recycled).

The iron-transferrin bond is quite stable, but the interaction with specific receptors allows the easy transfer of the mineral to the cells in the moment of need.

Iron metabolism (in short)

Iron is introduced into the body with food and is absorbed into the intestine after being transformed by the digestive juices of the stomach.

Once absorbed in the intestine, iron is transported in the blood by transferrin and transported to the storage organs (mainly the liver), where it binds to ferritin.

Why do you measure

The dosage of sideremia serves to check if the iron levels are within the norm.

When the test is indicated

The sideremia dosage is not part of the routine tests, but is indicated in cases where the hemoglobin and hematocrit values ​​are abnormal.

The test can be useful to determine the causes of an eventual anemia and is also required during a treatment for iron deficiency, in order to assess whether the treatment is effective or to decide when to stop it.

In children who accidentally swallowed iron-based tablets, measuring the mineral in the blood is the only method to determine the severity of the poisoning .

Sideremia can be used, together with total iron-binding capacity (TIBC), as a screening test for hemochromatosis, in order to allow early recognition of the disease.

Why is it measured?

The serum test can be requested by the doctor if excessive or too low levels of iron in the blood are suspected in the patient.

• Low iron levels can cause anemia and are generally due to deficiencies (reduced dietary intake or increased demands) or poor absorption; furthermore, they can signal huge or prolonged bleeding, pregnancy, rapid growth (in children), infectious diseases, neoplasms and acute myocardial infarction.
• On the other hand, elevated iron levels may be due to prolonged transfusion therapy or, rarely, to ingestion of an overdose of iron (generally in children). Sideremia is also increased in hemolytic syndromes, thalassemia, pernicious anemia, medullary aplasia, sideroblastic anemia, chronic alcoholism, renal pathologies, acute hepatitis and liver cirrhosis.

A single exam is not sufficient to diagnose iron deficiency; therefore the serum test is generally accompanied by other tests, such as the TIBC (acronym of "Total Iron Binding Capacity", or total capacity to bind iron), except in cases of suspected iron poisoning.

Normal values

Under normal conditions, the sideremia values ​​in humans range from 53 to 167 mcg per deciliter of blood, while in women the values ​​are slightly lower (49-151 mcg / dl).

In addition to sex, values ​​are also influenced by age, time of day, environmental circumstances (such as the menstrual flow, in which it decreases) and the intake of certain drugs or iron-based supplements (which must be absolutely suspended in the 2-3 days preceding the exam).

Even more simply, eating large amounts of red meat (such as horse or beef) in the 24-48 hours prior to the exam can offset the results.

Sideremia Low - Causes

A low sideremia is found in different situations:

• Insufficient dietary intake of iron (malnutrition, vegetarian diets, drastic diets etc.);
• Increased iron requirement, as happens in pregnancy, during lactation and in childhood;
• Reduced absorption of the mineral at intestinal level (celiac disease, chronic diarrhea, alcoholism, abuse of laxatives, Crohn's disease and other diseases of the gastrointestinal tract);
• Increased use of iron in bone marrow, as in endurance athletes;
• Excessive loss of iron (chronic bleeding, too abundant menstrual flows or bleeding in the digestive tract due to an ulcer).

The causes of a reduction in iron in the blood can also be:

• Iron deficiency anemia (ie due to iron deficiency);
• Diabetes;
• Old age;
• Kidney failure;
• Infectious diseases (tuberculosis, lung abscess, bacterial endocarditis etc.);
• Some tumors (breast, lung, Hodgkin's lymphoma etc.);
• Heart attack;
• Intake of some substances (ACTH and testosterone) and some drugs (colchicine and methicillin).

Symptoms associated with low serum iron

• Lack of breath;
• Headache;
• Dizziness;
• Drowsiness;
• Fatigue;
• Angina (chest pain);
• Palpitations;
• Leg pains;
• Difficulty concentrating;
• Hair loss;
• Pallor of the skin and mucous membranes;
• Burning sensation in the tongue;
• Wounds on the sides of the mouth;
• Brittle nails.

Sideremia Alta - Causes

A high serum iron is a common consequence of these conditions:

• Excessive introduction of iron by numerous blood transfusions;
• Insufficient use of iron in the bone marrow (aplastic anemias, megaloblastic anemias, etc.);
• Excessive lysis of red blood cells (haemolytic anemias);
• Cellular necrosis of the iron deposition organs (as in acute viral hepatitis and in liver cirrhosis);
• Hemochromatosis (hereditary disease characterized by excessive absorption of iron, which is deposited throughout the body, especially in the liver, pancreas and skin, damaging them);
• Hemosiderosis (excessive iron accumulation).

High serum iron levels may also be due to:

• Genetic diseases (thalassemia);
• Therapies with iron or accidental overdose (poisoning);
• Intake of some substances (estrogens and contraceptive pill) and some drugs (methyldopa and chloramphenicol).

Symptoms associated with high serum iron

• Increased blood glucose, triglycerides and liver transaminases;
• Joint pain;
• Adrenal and thyroid disorders;
• Enlarged liver and spleen;
• Fatigue and lack of energy;
• Mood disorders (anxiety and nervousness);
• Abdominal pain;
• Tachycardia;
• Arrhythmia;
• Hair loss;
• Sexual dysfunction (loss of libido, irregular or absent menstrual cycle in women or impotence in men).

How to measure it

Type of sample

The sample to be analyzed consists of blood taken from the arm.

Sample Collection

To perform the serum test it is sufficient to take, through a puncture, a blood sample from the vein of an arm.

Preparation

The examination is carried out through a simple blood sample, after a fast of at least 10 hours.

Usually, the sampling is done in the morning, when the iron levels reach higher levels than the evening ones.

What factors can influence the results

For at least 2-3 days before taking the sample, it is advisable to stop taking tablets or iron-based tablets (otherwise, the values ​​would be distorted).

Contraceptive pills, estrogen-based preparations, strong intake of alcoholic beverages, methyldopa and chloramphenicol can all increase iron levels.

ACTH, colchicine, deferoxamine, methicillin and testosterone can cause, instead, lowering of the sideremia.

Sideraemia and circadian cycle

The levels of iron present in the circulation follow a circadian cycle, being decreasing during the day until about 21 to increase and reach the maximum values ​​between 7 and 10 in the morning.

Even greater variations were observed in the determinations carried out on different days.

Interpretation of results

The simple dosage of sideremia, also considering the remarkable variability of its values, does not have a great clinical relevance, while it becomes very useful if associated with other tests, such as ferritinemia and transferrinemia, which help to build a more complete picture of ferric metabolism body.

Therefore, to better assess an alteration of iron levels in the blood, and better understand the possible cause, ferritin and transferrin must also be taken into account.

• Ferritin indicates the situation of the body's iron reserves: a low value is considered the earliest indicator of a depletion of the trace element deposits.
• Transferrin is the molecule that carries iron in the circulation. In addition to transferrin, it is possible to calculate its total capacity to bind iron, called TIBC.

An iron deficiency causes the increase of transferrin and TIBC, therefore the increase in the value of TIBC indicates a real increase in the body's need for iron, as happens, for example, in all iron deficiency anemias, during pregnancy, during lactation and in the child during growth.

How to read the exam

The sideremia reference values ​​are not unique, as they can change according to the patient's age, sex and even analytical methods and the instruments used in the various laboratories.

For this reason, it is preferable to consult the specific ranges indicated for each analysis directly on the report. It should also be remembered that it is important that the results are assessed as a whole by the medical doctor, who knows the patient's medical history.

What are the treatments in the case of altered values ​​of the sideremia?

To restore the sideremia to normal values, the underlying cause must be treated. Therefore, the most appropriate therapy is indicated by the doctor. At the same time, it is possible to implement a correct and specific diet.