Lipidemia

Lipidemia - reduction of lipoproteins in the blood plasma, caused by primary (genetic) or secondary factors. Usually this condition is asymptomatic and is diagnosed accidentally, when screening lipid levels. 

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

Causes of the hypolipidemia

The diagnosis of lipid lowering is made when the level of total cholesterol:

• <120 mg / dL (<3.1 mmol / L) or LDL
• <50 mg / dl (<0.13 mmol / l).

Secondary causes of lipid lowering are much more frequent than primary ones, and include hyperthyroidism, chronic infections and other infectious and inflammatory diseases, hematologic and other malignant neoplasms, eating disorders (including what accompanies chronic alcohol use) and impaired absorption in the digestive tract. If an unexpected laboratory finding is found in the form of a low level of cholesterol or LDL in a patient who does not take lipid-lowering medications, a diagnostic examination, including the determination of ACT, ALT and TSH, should be immediately instituted; The negative result of the additional examination speaks in favor of possible primary causes that can cause a condition such as hypolipidemia.

There are three major disorders known as primary causes of lipid lowering, in which single or multiple genetic mutations lead to hyperproduction or impaired LDL clearance.

Abetalipoproteinemia (Bazen-Kornzweig Syndrome) is an autosomal recessive hereditary pathology caused by a mutation in the gene of the microsomal trigylceride carrier protein, a special protein necessary for the process of chylomicron and VLDL formation. Fats coming from food can not be absorbed, and both metabolic pathways of lipoproteins are virtually absent in the blood serum. In this case, total cholesterol usually <45 mg / dl (1.16 mmol / l), TG <20 mg / dl (<0.23 mmol / l) and LDL are not determinable. This condition is often first diagnosed in newborns with fat malabsorption syndrome, steatorrhea, and growth and developmental disorders. The result may be a delay in mental development. Since  vitamin E is  distributed around the peripheral tissues through VLDL and LDL, the majority of patients eventually develop severe vitamin E deficiency. Clinical symptoms and signs include changes in vision resulting from gradual development of retinal degeneration, development of sensory neuropathy, spinal cord and cerebellar symptoms (movement coordination disorders, ataxia and hypertonic muscle), which eventually lead to lethal outcome. Acanthocytosis of erythrocytes is a characteristic feature found by microscopic examination of blood. Lipidemia is established on the basis of the absence of apo B in the blood plasma; with biopsy of the small intestine, there is a lack of a microsomal carrier protein. Such a hypolipidemia is treated with the appointment of high doses (100-300 mg / kg of weight 1 time / day) of vitamin E in combination with the addition of fats and other fat-soluble vitamins to the diet.

Hypobetalipoproteinemia is an autosomal dominant hereditary pathology caused by mutations in the gene coding for apo B. Heterozygous patients have a shortened apo B, which leads to an acceleration in the clearance of LDL. In the manifestation of pathology, there is no clinical symptomatology, except for total cholesterol level <120 mg / dl and LDL <80 mg / dl. The level of triglycerides is normal. In homozygous patients, a shorter truncation of apo B leads to a more pronounced decrease in lipid levels (total cholesterol <80 mg / dL, LDL <20 mg / dl) or complete cessation of apo B synthesis leading to the development of abietipoproteinemia symptoms. Lipidemia is established on the basis of detectable low LDL and apo B levels; hypobetalipoproteinemia and abetalipoproteinemia are characteristic states that are inherited through generations. Hetero- and homozygous patients with low but detectable LDL do not need any therapy. This hypolipidemia is treated in homozygous patients with undetectable levels of LDL as well as abetalipoproteinemia.

The disease of delay of chylomicrons is a condition inherited by an autosomal recessive type and caused by an unknown mutation leading to the development of a deficit of apo B secretion from enterocytes. Synthesis of chylomicrons is absent, but VLDL synthesis remains intact. In newborns with this pathology, malabsorption syndrome of fats, steatorrhea and delayed growth and physical development are found, which can lead to the development of neurological symptoms similar to those with abelalipoproteinemia. Lipidemia is established on the basis of the results of a small intestine biopsy conducted in patients with a reduced level of cholesterol in the blood plasma and the absence of postprandial chylomicrons. Treatment consists in dietotherapy (food rich in fats and fat-soluble vitamins).

[7], [8],

Treatment of the hypolipidemia

Secondary hypolipidemia is treated by the method of eliminating the underlying cause. Primary lipid lowering often does not require treatment, but patients with certain genetic abnormalities need the appointment of high doses of vitamin E.