Diagnosis of iron deficiency anemia

In accordance with the recommendations of the WHO, the following criteria for the diagnosis of iron deficiency anemia in children are standardized:

• decrease in the level of SLC less than 12 μmol / l;
• an increase in OJSS more than 69 μmol / l;
• transferrin saturation with iron less than 17%;
• the hemoglobin content is lower than 110 g / l under the age of 6 years and below 120 g / l - over the age of 6 years.

Thus, WHO recommends fairly accurate criteria for the diagnosis of iron deficiency anemia, but the methods of diagnosis require blood sampling from the vein and carrying out quite expensive biochemical studies, which is not always possible in Ukrainian medical institutions. There are attempts to minimize the criteria for the diagnosis of iron deficiency anemia.

The Federal Service for Disease Control, CDC, headquartered in Atlanta, Georgia, USA recommends the use of 2 available criteria for the diagnosis of iron deficiency anemia: reduction of hemoglobin and hematocrit (Ht ) in the absence of other diseases in the patient. Establish a hypothetical diagnosis of iron deficiency anemia and prescribe treatment with iron preparations for 4 weeks from the calculation of 3 mg of elemental iron per 1 kg of the patient's body weight per day. The advantage of these recommendations is the registration of a response to iron therapy with strictly fixed criteria. By the end of the fourth week of treatment, the hemoglobin concentration should increase by 10 g / l with respect to the initial, and Ht - by 3%. Such a response confirms the diagnosis of "iron-deficiency anemia", and the treatment continues for several months. If the answer is not received, it is recommended to stop the treatment with iron preparations and review this case from the point of view of the diagnosis of the process. Iron overload for 4 weeks when taking iron preparations inside is unlikely.

[1], [2], [3], [4], [5], [6], [7], [8], [9]

Laboratory diagnostics of iron deficiency anemia in children

Laboratory diagnostics of iron deficiency anemia is carried out with the help of:

• a general blood test performed by a "manual" method;
• a blood test performed on an automatic blood analyzer;
• biochemical research.

When diagnosing any anemia, it is mandatory to perform a general blood test with the determination of the number of reticulocytes. The doctor focuses on the hypochromic and microcytic nature of anemia. In the general analysis of blood, performed by a "manual" method, they reveal:

• decrease in hemoglobin concentration (<110 g / l);
• normal or reduced (<3.8x10 ¹² / l) the number of red blood cells;
• decrease in the color index (<0.76);
• normal (less often slightly elevated) content of reticulocytes (0.2-1.2%);
• increase in erythrocyte sedimentation rate (ESR) (> 12-16 mm / h);
• anisocytosis (characterized by microcytomas) and poikilocytosis of erythrocytes.

The parameter determination error can reach 5% or more. The cost of one general blood test is about $ 5.

An accurate and convenient method of diagnosis and differential diagnosis is the method for determining erythrocyte indices on automatic blood analyzers. The study is carried out in both venous and capillary blood. The error in determining the parameters is much lower than in the "manual" method, and is less than 1%. With the development of iron deficiency, in the past, the indicator of expressiveness of red cell anisocytosis - RDW (norm <14.5%) is increasing. With the definition of MCV, microcytosis is recorded (normal - 80-94 fl). In addition, the mean hemoglobin content in erythrocyte-MCH (norm-27-31 pg) and the mean concentration of hemoglobin in erythrocyte-ICSU (norm-32-36 g / l) decrease. The cost of one analysis performed on an automatic hematological analyzer is about 3 US dollars.

Biochemical indicators confirming iron deficiency in the body are informative, but require blood sampling from the vein and is expensive (the cost of a single determination of SJ, OJSS, SF is more than 33 US dollars). The most important criterion for iron deficiency is the decrease in the concentration of SF (<30 ng / ml). However, ferritin is a protein of the acute phase of inflammation, its concentration against the background of inflammation or pregnancy can be increased and "disguises" the available iron deficiency. It should be borne in mind that the SS index is unstable, as the iron content in the body is subject to fluctuations having a diurnal rhythm, and depends on the diet. The saturation of transferrin with iron is the calculated coefficient, determined by the formula:

(SLC / OZHSS) x 100%.

Transferrin can not be saturated with iron more than 50%, which is due to its biochemical structure, most often saturation is from 30 to 40%. If the saturation of transferrin by iron is below 16%, effective erythropoiesis is impossible.

Plan for examination of a patient with iron deficiency anemia

Analgeses confirming the presence of iron deficiency anemia

1. Clinical analysis of blood with determination of the number of reticulocytes and morphological characteristics of erythrocytes.
2. "Iron complex" of blood, including determination of serum iron level, total iron binding capacity of serum, latent iron-binding capacity of glandlet, iron transferrin saturation coefficient.

When assigning a study in order to avoid mistakes in interpreting the results, it is necessary to consider the following factors.

1. The study should be performed before the beginning of treatment with iron preparations; if the study is carried out after taking iron preparations even for a short period of time, the results obtained do not reflect the true iron content in the serum. If a child begins to receive iron preparations, then the study can be conducted no earlier than 10 days after their withdrawal.
2. Transfusions of erythrocytes, often carried out until the nature of anemia is clarified, for example, with a marked decrease in hemoglobin level, also distorts the estimate of the true iron content in the serum.
3. Blood for the study should be taken in the morning, as there are daily fluctuations in the concentration of iron in the serum (in the morning the iron level is higher). In addition, the content of iron in the blood serum affects the phase of the menstrual cycle (just before menstruation and during it the serum iron level is higher), acute hepatitis and cirrhosis (increase). There may be random variations in the parameters studied.
4. To test serum for iron, special tubes must be used, twice washed with distilled water, since the use of tap water containing minor amounts of iron affects the results of the study. To dry the tubes, do not use drying cabinets, because from their walls when heated in a dish gets a small amount of iron.

[10], [11], [12], [13]

Studies that specify the cause of iron deficiency anemia in children

1. Biochemical blood test: ALT, ACT, FMFA, bilirubin, urea, creatinine, sugar, cholesterol, total protein, proteinogram.
2. General analysis of urine, coprogram.
3. Analysis of feces for eggs of helminths.
4. The analysis of feces on the response of Gregersen.
5. Coagulogram with the determination of the dynamic properties of platelets (according to indications).
6. RNGA with intestinal group (according to indications).
7. Ultrasound of the organs of the abdominal cavity, kidneys, bladder, small pelvis.
8. Endoscopic examination: fibrogastroduodenoscopy, sigmoidoscopy, fibrocolonoscopy (according to indications).
9. X-ray of the esophagus and stomach; irrigography, chest radiograph (according to indications).
10. Examination of ENT doctor, endocrinologist, gynecologist, other specialists (according to indications).
11. Scintigraphy for the exclusion of Meckel's diverticulum (according to indications).

After the diagnosis of iron deficiency anemia, it is necessary to clarify its cause. For this purpose, a comprehensive survey is conducted. First of all, the pathology of the gastrointestinal tract is excluded, which can lead to chronic blood loss and / or impaired digestion of iron. They perform fibrogastroduodenoscopy, colonoscopy, sigmoidoscopy, reaction to latent blood, X-ray examination of the gastrointestinal tract. It is necessary to search persistently for helminthic invasion by the withered head, ascarids, hookworms. Girls and women need to be examined by a gynecologist and exclusion of pathology from the genitals, as the cause of iron deficiency in the body. In addition, it is necessary to clarify whether the patient does not suffer from hemorrhagic diathesis: thrombocytopenia, thrombocytopathy, coagulopathy, telangiectasia.

Although hematuria rarely lead to the development of iron deficiency anemia, it should be remembered that a permanent loss of erythrocytes in the urine can not but lead to iron deficiency. This refers to hemoglobinuria. Deficiency of iron in the body can be not only a consequence of increased blood loss, but also a result of a violation of the assimilation of iron, that is, we must exclude conditions leading to malabsorption syndrome.

The cause of iron deficiency anemia may be a condition in which blood enters a closed cavity, from which iron is practically not utilized. This is possible with glomus tumors that originate from arteriovenous anastomoses. Glomus tumors are localized in the stomach, retroperitoneum, mesentery of the small intestine, thicker than the anterior abdominal wall. Chronic infections, endocrine diseases, tumors, violations of iron transport in the body can also cause iron deficiency anemia. Thus, a patient with iron deficiency anemia requires an in-depth and comprehensive clinical laboratory study.

According to WHO recommendations, in case of difficulty in determining the cause of iron deficiency, the term "iron-deficiency anemia of unspecified origin" should be used.

Differential diagnosis of iron deficiency anemia in children

Differential diagnosis of iron deficiency anemia should be conducted with anemia in chronic diseases and anemia caused by a deficiency of folic acid or vitamin B ₁₂, that is, within the group of "scarce" anemia.

Anemia in chronic diseases is an independent nosological form, which has a code for ICD-10 - D63.8. The main causes of anemia in chronic diseases:

• presence of the main chronic disease (usually known to doctors!);
• infections that occur chronically (tuberculosis, sepsis, osteomyelitis);
• systemic connective tissue diseases (rheumatoid arthritis, systemic lupus erythematosus);
• chronic liver diseases (hepatitis, cirrhosis);
• malignant neoplasms.

The pathogenesis of anemia in chronic diseases is finally unclear, but the following mechanisms are known:

• a violation of the metabolism of iron with its sufficient amount in the body, with the use of iron and its reutilization from macrophages difficult;
• hemolysis of erythrocytes;
• suppression of erythropoiesis by inhibitors (middle molecules, products of lipid peroxidation, cytokines, TNF, IL-1, replacement by tumor cells;
• inadequate production of erythropoietin: an increase in its production in response to anemia, but its amount is insufficient to compensate for anemia.

Laboratory criteria for diagnosis of anemia in chronic diseases:

• decrease in hemoglobin concentration (unsharp);
• decrease in the number of erythrocytes (unsharp);
• microcytic anemia;
• normoregeneratorny character of anemia;
• decreased SJ;
• decreased OZHSS (!);
• normal or elevated (!) content of SF;
• an increase in ESR.

[14], [15], [16], [17], [18], [19], [20], [21]