Latent (unsaturated) iron-binding capacity of blood serum

The maximum amount of iron that transferrin can attach to its complete saturation is called the total iron binding capacity of the serum (TIBC). TRI correlates with serum transferrin levels, but the relationship between them is nonlinear and is disrupted in diseases that affect the binding capacity of transferrin and other iron-binding proteins. The additional amount of iron that can bind to transferrin is the unsaturated (latent) serum iron-binding capacity (IBC). Thus, the OISS represents the sum of two terms: the iron-saturated part of transferrin (iron content in serum) and the unsaturated part (IUS):

TISS = Serum iron + NISS The ratio of the amount of iron associated with transferrin to TISS gives an idea of the coefficient (degree) of transferrin saturation: Saturation coefficient, % = Serum iron / TISS * 100

Indications for the study

Diagnosis of iron deficiency conditions;
diagnosis of anemia;
chronic blood loss;
gastrointestinal diseases;
severe illnesses accompanied by significant loss or increased protein intake;
systemic connective tissue diseases, severe chronic diseases.

Research method.

When determining the TLC, excess ferric iron is added to the patient’s blood sample, and the ions remaining in the serum after transferrin saturation are precipitated with magnesium carbonate. The concentration of total iron, determined by the colorimetric method in the supernatant, reflects the value of the total iron content.

When determining NVSS, a solution of divalent iron salt is added to the patient’s blood serum. Excess iron remaining in the serum after transferrin saturation is determined by reaction with chromogen using a colorimetric method. NISS is calculated as the difference between the total amount of iron ions added to the sample and the amount of iron ions determined during the reaction, i.e., not bound by proteins.

Increased values

Iron deficiency conditions:
chronic blood loss;
insufficient intake of iron from food;
impaired iron absorption caused by gastrointestinal diseases;
increased utilization and consumption of iron (late pregnancy, active growth).

true polycythemia.

Reduced values

Severe diseases accompanied by significant loss or increased protein intake: nephrotic syndrome;
chronic renal failure;
severe burns;
chronic infections and active inflammatory processes;
severe liver diseases with disruption of its protein-synthetic function;

kwashiorkor;

hemochromatosis;

atransferrinemia;

hemolytic anemia;

megaloblastic anemia.

atransferrinemia;

excess iron saturation (iron poisoning, frequent blood transfusions, inadequate therapy with iron supplements).

The latent iron-binding capacity of serum is a laboratory indicator that reflects the potential ability of blood serum to bind additional amounts of iron.

Synonyms Russian

Unsaturated iron-binding capacity of serum, NISH, LVSS.

English synonyms

Iron indices, iron profile, unsaturated iron binding capacity, UIBC.

Research method

Colorimetric photometric method.

Units

μmol/L (micromoles per liter).

What biomaterial can be used for research?

Venous blood.

How to properly prepare for research?

Do not eat for 8 hours before the test; you can drink clean still water.
Stop taking medications containing iron 72 hours before the test.
Avoid physical and emotional stress and do not smoke for 30 minutes before the test.

General information about the study

Iron is an important trace element in the body. It is part of hemoglobin, which fills red blood cells and allows them to carry oxygen from the lungs to organs and tissues.

Iron is part of the muscle protein myoglobin and some enzymes. It is absorbed from food and then transferred by transferrin, a special protein that is formed in the liver.

Usually the body contains 4-5 g of iron, about 3-4 mg (0.1% of the total) circulates in the blood “in conjunction” with transferrin. The level of transferrin depends on the functioning of the liver and on the person’s diet. Normally, 1/3 of the transferrin binding centers are filled with iron, the remaining 2/3 remain in reserve. The serum latent iron binding capacity (SIBC) reflects how much transferrin is “unfilled” with iron.

This parameter can be calculated using the following formula: LVSS = TGSS - iron in serum (TGSS is the total iron-binding capacity of blood serum - an indicator characterizing the maximum ability of transferrin to “fill up” with iron).

With iron deficiency, there is more transferrin so that this protein can bind to the small amount of iron in the serum. Accordingly, the amount of transferrin “not occupied” by iron increases, that is, the latent iron-binding capacity of the serum.

On the contrary, with an excess of iron, almost all transferrin binding centers are occupied by this trace element, therefore the latent iron-binding capacity of the serum decreases.

The amount of serum iron can vary significantly from one day to the next and even within one day (especially in the morning), however, the PVSS and LVSS normally remain relatively stable.

In the early stages, iron deficiency sometimes does not show any symptoms. If a person is otherwise healthy, then the disease can make itself felt only when hemoglobin decreases below 100 g/l. Usually these are complaints of weakness, fatigue, dizziness, and headaches.

What is the research used for?

To determine the amount of iron in the body and its relationship with blood proteins (together with a test for iron in serum, sometimes with a test for PVSS and transferrin). These studies make it possible to calculate the percentage of transferrin saturation with iron, that is, to determine exactly how much iron the blood carries. This indicator most accurately characterizes iron metabolism.

The purpose of such tests is to diagnose iron deficiency or excess. In patients with anemia, they can help determine whether the disease is caused by iron deficiency or other causes, such as a chronic disease or vitamin B12 deficiency.

When is the study scheduled?

When any abnormalities are detected in the general blood test, analysis of hemoglobin, hematocrit, number of red blood cells (together with a test for iron in serum).
If you suspect a deficiency or excess of iron in the body. With a severe lack of iron, shortness of breath, pain in the chest and head, and weakness in the legs occur. Some people have a desire to eat unusual foods (chalk, clay), a burning sensation on the tip of the tongue, and cracks in the corners of the mouth. Children may have learning difficulties.
If you suspect iron overload (hemochromatosis). This condition manifests itself in different ways, such as joint or abdominal pain, weakness, fatigue, decreased sexual desire, and irregular heart rhythm.
When monitoring the effectiveness of treatment for iron deficiency or excess.

What do the results mean?

Reference values: 20 - 62 µmol/l.

Interpretation of the results of analysis for LVSS, as a rule, is made taking into account other indicators that assess iron metabolism.

Reasons for increasing the life insurance ratio

Anemia. It is usually caused by chronic blood loss or insufficient consumption of meat products.
Third trimester of pregnancy. In this case, serum iron levels decrease due to increased iron requirements.
Acute hepatitis.
Multiple blood transfusions, intramuscular iron administration, inadequate administration of iron supplements.

Reasons for the decrease in life insurance

Chronic diseases: systemic lupus erythematosus, rheumatoid arthritis, tuberculosis, bacterial endocarditis, Crohn's disease, etc.
Hypoproteinemia associated with absorption disorders, chronic liver disease, burns. A decrease in the amount of protein in the body leads, among other things, to a drop in the level of transferrin, which reduces the life span.
Hereditary hemochromatosis. In this disease, too much iron is absorbed from food, the excess of which is deposited in various organs, causing them to become damaged.
Thalassemia is a hereditary disease in which the structure of hemoglobin is changed.
Cirrhosis of the liver.
Glomerulonephritis is inflammation of the kidneys.

What can influence the result?

Estrogens and oral contraceptives lead to an increase in LVSS.
ACTH, corticosteroids, testosterone can reduce LVSS.
The amount of serum iron can vary significantly from day to day and even within one day (especially in the morning), however, the PVSS and PVSS normally remain relatively stable.

Interpretation of results

The following reference values have been established for THC: 45.3-77.1 µmol/l. Interpretation of the results of this test is carried out taking into account data from other laboratory tests. Only a doctor can properly evaluate them; self-diagnosis and self-medication are unacceptable. An elevated reading usually indicates anemia. It may be caused by low levels of meat in the diet or significant blood loss. An increase in PVSS may also be observed in patients with acute hepatitis. In late pregnancy, an increase in levels is caused by an increase in the need for iron.

If the test results are below normal, this may indicate various diseases (for example, tuberculosis, rheumatoid arthritis). To establish an accurate diagnosis in most cases, a comprehensive examination is required.

Important information

The information on the site is for reference purposes and is not a public offer. For up-to-date information, contact the contractor’s medical center or the STK0LAB call center at: 8-800-505-90-13
The service catalog indicates the maximum possible period for completing the study. It reflects the time it takes to complete the study in the laboratory and does not include the time for delivery of the biomaterial to the laboratory.
Please check the deadlines for tests taken at regional medical centers by calling the contact numbers of the centers. To view the list of tests offered, click on the section of the catalog that interests you.
Please note that collection of biomaterial for research from children under 15 years of age is possible only in the presence of parents or legal representatives. After 15 years of age, the presence of parents or legal representatives is not required.

Description

The latent (unsaturated) iron-binding capacity of blood serum (LBC) reflects the ability of blood serum to bind iron. Latent iron-binding capacity of serum: reflects the reserve capacity of transferrin, shows how much transferrin is free to bind iron, characterizes how much transferrin is not saturated with iron. The indicator is calculated based on two parameters: serum iron and total iron-binding capacity of blood serum (TIBC), which characterizes the maximum possible filling of transferrin with iron. The iron binding capacity of serum varies depending on the iron content in the body. In iron deficiency anemia, when iron levels decrease, transferrin levels increase. Transferrin “unoccupied” by iron is the LVSS, therefore, the LVSS and TGSS increase. With excessive intake of iron into the body, LVSS decreases. Low levels of serum iron and low LVSS are characteristic of anemia that occurs against the background of malignant tumors, against the background of chronic diseases.

Indications for the study

Analysis for OZhSS

, as a rule, are prescribed in conjunction with other laboratory tests to determine the amount of a microelement and evaluate its relationship with proteins. The results obtained make it possible to identify iron deficiency or excess and establish the exact cause of anemia.

The test is carried out in the following cases:

symptoms of iron excess or deficiency;
identified deviations from normal values in the results of the UAC;
monitoring the progress of treatment.

Microelement deficiency does not manifest itself in any way over a long period of time. First of all, symptoms such as dizziness, weakness, and headaches appear. With a significant lack of iron, shortness of breath and pain in the chest appear. Unconventional food preferences may appear. When there is an excess of a microelement, symptoms such as cardiac dysfunction, pain in the abdomen or in the joint area appear.