Lipoid nephrosis

Lipoid nephrosis is an independent form of kidney damage only in children with minimal (podocytic) glomerular changes.

Lipoid nephrosis is a disease of young children (mostly 2-4 years old), more often boys. Lipoid nephrosis is a kidney disease in which morphologically there are only minimal changes. WHO experts define lipoid nephrosis as minimal changes "disease of small podocyte processes", which undergo dysplastic changes, the membrane and mesangium react secondarily.

Electron microscopy reveals only minimal changes in the glomeruli of the kidney with damage or disappearance of small processes (pedicles) of podocytes, their displacement and spreading along the basement membrane of the glomerular capillaries.

Immunohistochemical examination of kidney biopsies in lipoid nephrosis gives a negative result and helps differentiate lipoid nephrosis from other types of glomerulonephritis. The most important evidence is the absence of deposits containing IgG, IgM, complement and the corresponding antigen in lipoid nephrosis according to immunofluorescence data.

The causes of lipoid nephrosis are unknown.

Dysfunction of the T-cell immunity system, increased activity of the T-suppressor subpopulation and hyperproduction of cytokines play a role in the pathogenesis of lipoid nephrosis. Increased activity of IL-2, IL-4, IL-8, IL-10 is found in the blood serum of patients. Interleukin-8 plays an important role in the pathogenesis of impaired glomerular filter selectivity. The charge-selective function of the glomerular filtration barrier is lost, resulting in increased permeability of capillaries for protein, especially negatively charged albumins. Proteinuria (mainly albuminuria) develops. Increased filtration of protein by glomerular capillaries leads to functional overstrain of the tubular apparatus. Resorptive tubular insufficiency occurs due to increased reabsorption of filtered protein.

Developing hypoalbuminemia leads to a decrease in the oncotic pressure of blood plasma and creates the possibility for its transudation from the vascular bed into the interstitial space. This, in turn, leads to a decrease in the circulating blood volume (CBV). A decrease in CBV leads to a decrease in perfusion pressure in the kidneys, which activates the renin-angiotensin-aldosterone system (RAAS). Activation of RAAS stimulates sodium reabsorption in the distal tubules. Reduced CBV stimulates the release of antidiuretic hormone (ADH), which enhances water reabsorption in the collecting tubules of the kidney. In addition, atrial natriuretic peptide also contributes to the disruption of transport processes in the collecting tubules of the renal tubules and the formation of edema.

Reabsorbed sodium and water enter the interstitial space, which increases edema in lipoid nephrosis.

An additional pathogenetic factor in the development of edema in lipoid nephrosis is the functional insufficiency of the lymphatic system of the kidneys, that is, impaired lymph flow.

Severe edema in lipoid nephrosis occurs when the serum albumin level falls below 25 g/l. The developing hypoproteinemia stimulates protein synthesis in the liver, including lipoproteins. However, lipid catabolism is reduced due to a decrease in the blood plasma level of lipoprotein lipase, the main enzyme system that affects the removal of lipids. As a result, hyperlipidemia and dyslipidemia develop: an increase in the content of cholesterol, triglycerides, and phospholipids in the blood.

Loss of protein by the kidneys leads to disruption of immune reactions - loss of IgG, IgA with urine, decreased synthesis of immunoglobulins and development of secondary immunodeficiency. Children with lipoid nephrosis are susceptible to viral and bacterial infections. This is also facilitated by the loss of vitamins and microelements. Massive proteinuria affects the transport of thyroid hormones.

The development of the disease and relapses are almost always preceded by acute respiratory viral infections or bacterial infections. With age, when the thymus matures, the tendency to relapses of lipoid nephrosis is clearly reduced.

Symptoms of lipoid nephrosis.Lipoid nephrosis develops gradually (gradually) and at first unnoticed by the child's parents and those around him. In the initial period, weakness, fatigue, and loss of appetite may be expressed. Pastosity appears on the face and legs, but parents remember this retrospectively. Edema increases and becomes noticeable - this is the reason for visiting a doctor. Edema spreads to the lumbar region, genitals, ascites and hydrothorax often develop. With lipoid nephrosis, edema is loose, easily moved, asymmetrical. The skin is pale, signs of hypopolyvitaminosis A, C, B ₁, B ₂ appear. Cracks may form on the skin, dry skin is noted. With large edema, shortness of breath, tachycardia appear, a functional systolic murmur is heard at the apex of the heart. Blood pressure is normal. At the height of edema formation, oliguria appears with a high relative density of urine (1.026-1.028).

Urine analysis reveals severe proteinuria, protein content of 3-3.5 g/day to 16 g/day or more. Cylindruria. Erythrocytes are single. At the onset of the disease, leukocyturia may be associated with the main process in the kidneys, it is an indicator of the activity of the process. Glomerular filtration for endogenous creatinine is higher than normal or normal. The albumin level in the blood is below 30-25 g/l, sometimes the albumin content in the patient is 15-10 g/l. The degree of decrease in albumin in the blood determines the severity of lipoid nephrosis and the severity of edema syndrome. The content of all major lipid fractions in the blood is increased. They can reach very high numbers: cholesterol above 6.5 mmol/l and up to 8.5-16 mmol/l; phospholipids 6.2-10.5 mmol/l. Blood serum protein is below 40-50 g/l. Characteristic is an increased ESR of 60-80 mm/hour.

The course of lipoid nephrosis is undulating, characterized by spontaneous remissions and relapses of the disease. Exacerbations can be caused by acute respiratory viral infections, bacterial infections; in children with allergic reactions, the corresponding allergen can play a role.

Remission is diagnosed when the blood albumin level reaches 35 g/l, in the absence of proteinuria. Relapse of lipoid nephrosis is diagnosed when significant proteinuria appears within 3 days.

Treatment of lipoid nephrosis.

The regimenis bed rest in the active phase, with pronounced edema for 7-14 days. Thereafter, the regimen does not provide for restrictions, on the contrary, an active motor regime is recommended in order to improve metabolic processes, blood and lymph circulation. The patient must be provided with access to fresh air, hygiene procedures, and exercise therapy.

Dietshould be complete taking into account age. In case of allergy - hypoallergenic. The amount of protein taking into account the age norm, in case of severe proteinuria - adding the amount of protein lost per day with urine. Fats are mainly vegetable. In case of severe hypercholesterolemia, reduce meat consumption, give preference to fish and poultry. Salt-free diet - 3-4 weeks with subsequent gradual introduction of sodium chloride up to 2-3 g. Hypochloride diet (up to 4-5 g) is recommended for the patient for many years. Fluid is not limited, since renal function is not impaired, especially since fluid restriction against the background of hypovolemia and treatment with glucocorticosteroids (GCS) worsens the rheological properties of the blood and can contribute to the development of thrombosis. During the period of swelling reduction and taking maximum doses of glucocorticosteroids, it is necessary to prescribe products containing potassium - baked potatoes, raisins, dried apricots, prunes, bananas, pumpkin, zucchini.

During the period of remission, the child does not need to limit diet and physical activity.

Drug treatment of lipoid nephrosisTreatment of the debut of lipoid nephrosis is mainly reduced to the prescription of glucocorticosteroids, the therapy of which is pathogenetic. Against the background of glucocorticosteroids, antibiotics are initially prescribed. Semi-synthetic penicillins, amoxiclav are used, and if the patient has a history of allergic reactions to penicillin, cephalosporins of the third and fourth generations.

Prednisolone is prescribed at a rate of 2 mg/kg/day in 3 or 4 doses daily until 3-4 consecutive negative daily urine protein tests. This usually occurs in the 3rd-4th week from the start of treatment. Then 2 mg/kg is prescribed every other day for 4-6 weeks; then 1.5 mg/kg every other day for 2 weeks; 1 mg/kg every other day for 4 weeks; 0.5 mg/kg every other day for 2 weeks with subsequent discontinuation of prednisolone. The course is 3 months. The results of treatment with glucocorticosteroids can be predicted by assessing the development of a diuretic response 4-7 days after the start of treatment. With rapid development of steroid diuresis, it can be assumed that the treatment will be successful. In the absence of a steroid response to diuresis or with its late development (by 3-4 weeks), treatment is ineffective in most cases. It is necessary to look for the cause of the lack of effect; renal dysplasia is possible. An examination is carried out to determine the possibility of hidden foci of infection and the treatment of foci of infection.

In case of steroid resistance - lack of effect from treatment with glucocorticosteroids for 4-8 weeks - cyclophosphamide 1.5-2.5 mg/kg/day is prescribed for 6-16 weeks in combination with prednisolone 0.5-1 mg/kg/day; then a course of maintenance therapy at half the dose of the cytostatic for another 3-6 months continuously.

In case of participation in the recurrence of lipoid nephrosis of atopy in children with a burdened allergic history, it is recommended to use intal, zaditen in the treatment.

For ARVI, reaferon, interferon, and children's anaferon are used.

Outpatient monitoring is carried out by a pediatrician and a nephrologist, they adjust the treatment if necessary. Consultations with an ENT doctor and a dentist are required twice a year.

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