Diagnosis of megaloblastic anemia

When collecting an anamnesis patient pay attention to:

• long-term use of antibiotics and anticonvulsants;
• type of diet / nutrition;
• the presence and duration of diarrhea;
• surgical interventions on the digestive tract.

A general blood test reveals:

• anemia;
• increased erythrocyte indices (MCV - can be up to 110-140 fl, RDW);
• macrocytosis of erythrocytes;
• many macro-ovalocytes;
• pronounced anisopoquilocytosis of erythrocytes;
• the presence of Jolly's bodies and the Keboat rings;
• leukopenia (up to 1.5x10 ⁹ / l);
• hyper-segmentation of neutrophil nuclei (5 or more segments);
• thrombocytopenia (up to 50x10 ⁹ / l).

When examining the bone marrow, there are signs of a megaloblastic type of hematopoiesis:

• cells are large;
• cores are granular, striated;
• cell cytoplasm is more mature than the nucleus;
• the dissociation of the nucleus and cytoplasm is more pronounced in more mature cells;
• there are cells containing nuclei with weakly condensed chromatin;
• multiple, sometimes pathological mitoses;
• remnants of nuclei, Jolly's body;
• cells containing 2 or 3 nuclei;
• qualitative disorders of erythropoiesis;
• huge (gigantic) metamyelocytes with horseshoe-shaped nuclei;
• hyper-segmentation of neutrophils;
• multinuclear megakaryocytes.

The results of the urine test reveal persistent proteinuria (a sign of a specific impairment of absorption of vitamin B ₁₂ in the ileum). Determine:

• the level of vitamin B ₁₂ in the blood serum: normal values - 200-300 pg / ml;
• serum folate level: normal value - more than 5-6 ng / ml (low - less than 3 ng / ml, borderline - 3-5 ng / ml);
• the level of folate in erythrocytes: the normal value is 74-640 ng / ml;
• the level of excretion of orotic acid for the diagnosis of oroturia.

The deoxyuridine test is performed to differentiate between deficiency of vitamin B ₁₂ and folic acid.

The Schilling test is performed to determine the activity of IF and the absorption of vitamin B ₁₂ in the intestine.

The Schilling test using commercial IF is conducted in the case of an impaired simple Schilling test for differentiation between IF pathologies and a specific impairment of absorption of vitamin B ₁₂ in the ileum (Imerslund-Gresbek syndrome) or transcobalamin II deficiency. In case of stratification of bacterial infection, the test should be repeated after a course of antibacterial therapy (after a tetracycline treatment the test usually comes to normal).

Conduct a study of gastric acidity (baseline and after histamine stimulation), the content of IF in gastric juice (including after the addition of hydrochloric acid to detect antibodies to IF in the gastric juice), a biopsy of the gastric mucosa.

Antibodies to IF and parietal cells in serum are determined.

In addition, the level of holotranscobalamin II in the blood serum is determined: when vitamin B deficiency is _{12, the} concentration of holotranscobalam II (cobalamin bound to transcobalamin II) is significantly lower than normal values, which precedes the decrease in the level of total cobalamin of blood serum.

In serum and urine, the concentration of methylmalonic acid and homocysteine is determined: with folate deficiency, methylmalonic acid is within normal limits, homocysteine is increased.

For the diagnosis of congenital methylmalonic aciduria, methylmalonate can be detected in the amniotic fluid or in the urine of a pregnant woman.

Malabsorption tests are performed.

For differential diagnosis between the deficit of vitamin B ₁₂ and folic acid are used alizerin red. When painting the smears of the bone marrow, stained megaloblasts, formed due to a deficiency of vitamin B ₁₂, and not folic acid.

Absorption of vitamin B _{12 is} assessed using the Schilling test, which uses a radioactive vitamin. The patient receives a small amount of vitamin B ₁₂ labeled with ⁵⁷ Co; in the body, it combines with the internal factor of the gastric secretion and enters the terminal part of the ileum, in which it is absorbed. Since the absorbed vitamin passes into the state associated with blood and tissue proteins, it is not normally excreted by urine. Then, a large dose (1000 μg intramuscularly) of non-radioactive vitamin is injected parenterally to saturate the circulating cobalamin-binding proteins (transcobalamin I and II) and to ensure the maximum excretion of the radioactive vitamin absorbed from the intestine with urine. Normally, in a daily portion of urine appears 10 - 35% of previously absorbed vitamin, in patients with a deficit of cobalamin excreted less than 3% of the administered dose. The relationship between the absorption of vitamin deficiency and the absence of an internal factor can be confirmed by a modified Schilling test: the radioactive vitamin is administered together with 30 mg of internal factor. If a violation of absorption of vitamin B _{12 is} caused by the absence of an internal factor, then the radioactive vitamin is absorbed in adequate amounts, excreted in the urine. On the other hand, if the impairment of absorption of the vitamin is due to an anomaly in the receptor zones in the ileum or other causes associated with the intestine, then after the introduction of the internal factor, the absorption of the vitamin is not normalized. If absorption impairment is not compensated, the sample can be repeated after the appointment of a course of broad-spectrum antibiotics (suppression of excess bacterial growth) and subsequent application of pancreatic enzymes (elimination of pancreatic insufficiency). The Schilling test is indicative only with careful collection of urine. The Schilling test to detect malabsorption of vitamin B ₁₂, in children is not applied, since it is associated with the introduction of a radioactive preparation into the body.

To exclude malabsorption of folates, the following test is carried out: the patient receives 5 mg of pteroylglutamic acid inside, which leads to an increase in the level of folic acid to 100 ng / ml for an hour. If the level of folic acid in the blood serum does not increase, malabsorption of folate is considered proven.

Patient examination plan for megaloblastic anemia

1. Analyzes confirming the presence of megaloblastic anemia.
   1. Clinical analysis of blood with determination of the number of reticulocytes and morphological characteristics of erythrocytes.
   2. Biochemical blood test, including determination of bilirubin and its fractions, serum iron.
   3. Myelogram.
2. Analyzes specifying options for megaloblastic anemia.
   1. Morphological examination of bone marrow smears when painted with red aliserin.
   2. Special methods:
      1. determination of vitamin B ₁₂ concentration in blood serum;
      2. determination of the concentration of folic acid in blood serum and erythrocytes;
      3. level of urinary excretion of methylmalonic acid;
      4. level of urinary excretion of formminglutamic acid.
3. Clinical examination to clarify the cause of anemia: urine tests, feces, endoscopic examination, gastric juice secretion, radiologic and morphological (according to indications) gastrointestinal examination, examinations of specialists, all examinations for individual indications.

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