The causes of sideroblastic anemia

Hereditary forms

Transmitted by recessive, linked to the X-chromosome (sick men) or autosomal-dominant type (sick men and women).

The metabolic block can be at the step of forming delta-aminolevulinic acid from glycine and succinyl CoA. This reaction requires pyridoxal phosphate, an active coenzyme of pyridoxine and synthetase of aminolevulinic acid. A low concentration in the erythrocytes of protoporphyrin and other porphyrins is detected laboratory-wise. In other cases, the metabolic block may be located between the stages of the formation of coproporphyrinogen and protoporphin IX, probably due to the insufficiency of the decarboxylase of coproporphyrinogen. In this case, there is an increase in co-proporphyrin with a decreased level of protoporphyrin in erythrocytes. Violation of the formation of protoporphyrin and heme causes the inability to use iron for hemoglobin synthesis, which leads to the accumulation of iron in the body and deposition of it in tissues and organs.

Clinical symptoms of the disease are manifested, as a rule, in late childhood. Patients develop anemic syndrome caused by hypoxia, and manifestations of tissue hemosiderosis due to the deposition of iron in the organs and tissues unused for the needs of hemocytopoiesis. Manifestations of anemic syndrome are lethargy, weakness, rapid fatigue during physical exertion. On examination, paleness of the skin and mucous membranes, adequate to the degree of anemia, is noted. Manifestations of hemosiderosis are hepatosplenomegaly; cardiovascular failure caused by the deposition of iron in the myocardium (patients complain of palpitations, dyspnea, tachycardia, edema); Possible development of diabetes, provoked by the deposition of iron in the pancreas; can be a defeat of the lungs, kidneys and other organs. In some patients, the skin becomes an earthy shade.

Purchased forms

Acquired forms of anemia associated with impaired synthesis of porphyrins may be due to lead poisoning.

Household lead intoxication in pediatric practice is quite common. They arise when eating foods stored in tinned or earthenware with the glaze of handicraft production. Lead poisoning is most often caused by the ingestion of lead paints, plasters, other materials saturated with lead dyes (newspapers, gypsum, gravel, lead content greater than 0.06%), home dust and soil particles (lead content 500 mg / kg) . From the atmosphere, lead comes not only by inhalation; most often it is deposited and enters the body with dust and soil particles. In infants, lead poisoning occurs when contaminated water is used to prepare milk mixtures. Toxication can lead to non-compliance with the necessary precautions when smelting lead at home.

With lead intoxication, the transformation of delta-aminolevulinic acid into porphobilinogen, coproporphyrinogen into protoporphyrinogen and incorporation of iron into protoporphyrin is disrupted. These three metabolic defects in heme synthesis are explained by the lead blocking of the sulfhydryl groups of enzymes participating in these synthesis steps, mainly delta-aminolevulinic acid dehydrase and gemsynthesis. As a result, the accumulation of delta-aminolevulinic acid in erythroid cells (and the appearance in large quantities in the urine), an increase in the content of protoporphyrin, coproporphyrinogen and iron in them. Anemia with lead intoxication (saturnism) is also due to increased hemolysis of red blood cells.

The clinical picture of Saturnism is characterized by symptoms of damage to the nervous system. Patients are disturbed by a headache, dizziness, bad sleep, irritability. Possible hyperkinetic syndrome, transient paresis. With prolonged and severe lead poisoning, polyneuritis, encephalopathy, and convulsive syndrome are possible. Appears lead colic, simulating the "sharp stomach". When examined - pallor of the skin, earthy-grayish shade - "lead pallor". A characteristic feature is the lead edge on the gums of the neck of the teeth. Dyspeptic disorders are noted.

Acquired sideroblastic anemia may be associated with the administration of certain drugs: anti-tuberculosis (cycloserine, isoniazid) used in tumor therapy (melphane, azathioprine), chloramphenicol, that is, secondary. The possibility of developing sideroblastic anemia against the background of taking the drugs mentioned above is explained by the fact that they are metabolic pyridoxine antagonists and partially inhibit the activity of synthetase of aminolevulinic acid.