Lipoid nephrosis is a disease characterized by a dystrophic lesion of the glomeruli with the development of nephrotic syndrome. At the initial stages, the symptoms are not determined, further edema of subcutaneous fat, weakness, severe thirst, appetite disorders develop. Diagnosis is based on the results of laboratory tests (general and biochemical blood and urine tests), examination of the patient, ultrasound of the kidneys. In controversial cases, a biopsy of the organ tissue is prescribed for subsequent histological examination. Treatment consists in the development of a special diet, the use of corticosteroids and diuretics, infusion therapy.
Meaning
Lipoid nephrosis (podocyte disease, idiopathic nephrotic syndrome of children, INSC) is a rare disease of unclear etiology, primarily affecting patients under the age of 4-5 years. Similar changes in the kidneys occur in adults with infectious conditions (tuberculosis, diphtheria, syphilis) or intoxication of the body with heavy metals. According to statistics, boys suffer from primary pathology twice as often as girls, secondary forms have no peculiarities in sexual distribution.
The cause of the condition lies in the impaired work of podocytes – cells covering capillaries in the glomeruli of the nephron. This is why the synonymous name of the disease is associated with it. Among all lesions of the renal system, the proportion of this nephrosis ranges from 0.4-0.6%, while the number of adults is about 20% of all cases.
Causes
The etiology of primary lipoid nephrosis is currently unknown. The influence of mainly endogenous factors is assumed. The study of pathogenetic processes revealed a violation of some links of T-cell immunity, leading to increased release of specific cytokines. In a number of patients, in addition to renal disorders, allergic pathologies and skin lesions (psoriasis) are noted.
Approximately 70% of patients with idiopathic nephrosis have special forms of the genes of the main histocompatibility complex – HLA-B8 and HLA-DR7. These serotypes are also associated with certain types of psoriasis. The main zone of their distribution – Northern and Western Europe – corresponds to the area of the greatest occurrence of INSC.
Secondary renal tissue damage, similar to lipoid nephrosis, usually occurs against the background of chronic pathologies of infectious, tumor or intoxication genesis. The cause of the disease is also considered to be abnormal activity of the immune system, leading to selective damage to the glomerular podocytes.
It is believed that people with secondary forms of nephrosis have a genetic predisposition to a nephrotic condition, and systemic pathology acts as a provoking factor, increasing the likelihood of indirect kidney damage. It is often possible to distinguish lipoid changes from some forms of glomerulonephritis only when examining the ultrastructure of the kidneys by electron microscopy.
Pathogenesis
It has been established that lipoid nephrosis is caused by disorders in the T-cell segment of the immune system. In idiopathic nephrotic syndrome of children, these anomalies are primary, due to genetic factors. Some systemic diseases can also abnormally activate the immune system. As a result, there is a sharp increase in the population of T-suppressors against the background of a significant release of cytokines and interleukins (IL).
Increased concentrations of IL-8, which reduces the charge of podocyte membranes, are particularly detrimental to the glomeruli of the nephron. As a result, the permeability of the capillary walls for proteins, mainly albumins, with a negative charge, increases. Getting into the tubular system, proteins clog it and contribute to the degradation of epithelial cells, eventually the nephron completely ceases to perform its functions.
The loss of significant amounts of protein potentiates a change in the rheological properties of blood plasma. A decrease in oncotic pressure along with a violation of the reabsorption of water and sodium ions in the kidneys causes edema. Hyperlipidemia develops as a compensatory reaction to improve blood viscosity. Massive “shutdown” of nephrons leads to chronic renal failure. Not only albumins are lost with urine, but also other proteins, in particular immunoglobulins of classes A and G. This is due to a decrease in the body’s resistance to infections up to secondary immunodeficiency.
Classification
The study of the causes of lipoid nephrosis and the development of principles for the classification of this condition are continuing. Currently, there are two main groups of pathology in practical urology – idiopathic and secondary nephrosis. The first type occurs mainly in children, and is considered by some researchers to be “true” lipoid nephrosis. The second variant of the disease develops in adults with systemic pathologies – some authors attribute it to varieties of glomerulonephritis. Minimal glomerular disorders in adults are divided into the following types according to etiological characteristics:
- Of an infectious nature. They include forms of nephrosis that occur under the influence of tuberculosis, syphilis, diphtheria, malaria and other diseases. Infections are considered the most common cause of LN in people over the age of 16.
- Of a tumor nature. Certain types of oncological diseases (lymphomas, lymphogranulomatosis) can lead to immune disorders with the release of large amounts of cytokines. The result is a lesion of podocytes, characteristic of lipoid nephrosis.
- Of an intoxicating nature. This group includes dystrophic lesions of the glomeruli caused by chronic poisoning with heavy metals – most often mercury or lead.
The above classification is considered controversial. The study of pathology is complicated by the fact that ultramicroscopic examination is necessary for reliable determination of podocyte disease. According to clinical and histological (by means of light microscopy) data, lipoid nephrosis is very similar to a number of inflammatory lesions of renal tissue – for example, membranous glomerulonephritis.
Symptoms
The clinical picture is usually unclear, at the initial stage the disease does not manifest itself in any way. The first symptoms are weakness, weakness, fatigue, appetite disorders. Then there are edema, usually first on the lower extremities, then on the face, neck, in the lumbar region. In severe cases, they are joined by the accumulation of fluid in the body cavities – ascites, hydrothorax, manifested by an increase in the abdomen, difficulty breathing. The skin is pale, edematous, the tissues are loose, they have long traces of fingers or other objects exerting pressure.
In children, the symptoms of idiopathic nephrotic syndrome are similar to the clinical picture in adults. The development of the disease is often preceded by a viral infection or sore throat. At first, parents note a decrease in the child’s motor activity, drowsiness, capriciousness, and often refusal of food. After that, edema and signs of ascites appear.
A feature of the children’s variety of pathology is the occurrence of a lack of vitamins A, C, B1. Polyhypovitaminosis is accompanied by dry skin, the formation of hemorrhages due to the fragility of capillaries, cracks in the corners of the mouth. Neurological disorders are possible – most often, a decrease in skin sensitivity. Urine in any form of the disease acquires a brown color and turbidity, its daily amount decreases (oliguria).
Lipoid nephrosis is characterized by a wave-like course, periods of exacerbations with the development of edema and other disorders alternate with episodes of spontaneous remission. Pathology does not manifest itself in the intercalary period, its presence can be determined only by proteinuria in the results of a general urine analysis. With frequent exacerbations, patients develop immunodeficiency due to the loss of blood globulins. Its signs are pneumonia, bronchitis, frequent pustular skin lesions. The appearance of skin cracks in the area of edema with the subsequent development of erysipelas is characteristic.
Complications
At the height of exacerbation, lipoid nephrosis is dangerous for the development of shock due to severe electrolyte disturbances and a decrease in the volume of circulating blood. There may be breathing problems due to pneumothorax, aggravated by a respiratory infection. Bacterial skin lesions, which often take on a severe character, pose a certain threat, there is a risk of developing sepsis. With a high frequency of attacks of the disease, hypochromic anemia is noted. In the absence of treatment, over time, the formation of a secondary shrunken kidney is possible, which causes CRF. According to some data, a lipoid lesion in the long term increases the risk of amyloidosis.
Diagnostics
The diagnosis of “lipoid nephrosis” is more often used in modern pediatric practice. In adults, a similar clinical picture is often defined by nephrologists as “minimal glomerular changes”. However, in most cases we are talking about the same process – the defeat of podocytes and glomeruli in the absence of immune complexes. To identify pathology, many diagnostic techniques are used, some of which are aimed at excluding other renal pathologies with a similar course. The algorithm for determining this nephrosis includes the following steps:
- Inspection and survey. Examination reveals swelling of the subcutaneous tissue of various localization of an asymmetrical nature, a puffy face, narrowed eye slits. To the touch, the edema is loose, inelastic, easily displaced, the skin above them sometimes has cracks and other damage. When questioned, weakness, lack of appetite, fatigue, increased thirst are determined.
- Laboratory tests. The most significant sign of the disease is the presence of proteinuria in urine tests. Protein losses can be up to 16 grams per day. Biochemical blood test confirms hypoalbuminemia up to 20-30 g/l, hyperlipidemia due to an increase in cholesterol and phospholipids. Creatinine and total nitrogen values in the absence of complications are usually within the normal range.
- Ultrasound examinations. Ultrasound of the kidneys reveals an increase in the size of organs, a weakening of differentiation between the cerebral and cortical substance. At the later stages of the development of pathology, with a long-term course, wrinkling and reduction of the kidneys may be detected.
- Histological studies. Taking a biopsy of kidney tissue followed by microscopic examination is considered the gold standard in the diagnosis of this nephrosis. Dystrophic changes in the glomeruli are determined, lipid deposits are found in the epithelium of the proximal tubules. During immunohistochemical examination, immune complexes are absent – an important sign of the difference between the disease and glomerulonephritis.
With the secondary nature of the pathology, the presence of infectious, tumor or intoxication conditions and their severity are determined. Differential diagnosis is carried out with membranous and other types of glomerulonephritis, amyloidosis of the kidneys, pyelonephritis. A distinctive feature of lipoid nephrosis is the relative preservation of the filtration capacity of the urinary system for a long time.
Treatment
Therapeutic measures are aimed at eliminating edema, replenishing protein deficiency, and preventing infectious complications. It is necessary to weaken the dystrophic processes in the kidneys, slow down the progression of the disease. For this purpose, a complex complex treatment is being developed, which includes not only the use of medicines, but also a special diet. The main components of disease therapy in nephrology are:
- Diet. The diet of patients should be dominated by proteins, the daily need for which increases to 2.5 grams per day. per kilogram of body weight. To reduce puffiness, it is recommended to reduce the consumption of table salt (no more than 1-2 grams per day). With severe hyperlipidemia, products containing low fats (poultry, white fish, vegetables) should be used.
- Appointment of diuretics. Diuretics are used to eliminate edema, especially in the acute period of the disease. At the same time, it is important to monitor the electrolyte composition of blood plasma in order to avoid complications.
- Immunosuppressive therapy. Glucocorticosteroids are practically the only group of drugs for the etiotropic treatment of lipoid nephrosis. They effectively reduce the activity of immunity and cytokine production, weakening the harmful effects of IL-8 on podocytes.
- Treatment of infectious complications. In the presence of pustular skin lesions, pneumonia, acute respiratory infections, antibacterial or antiviral agents are prescribed. Antibiotics and sulfonamide preparations are effective in bacterial infection.
- Infusion therapy. To improve the rheological properties of blood, drip infusion of special colloidal solutions is indicated. With threatening hypoproteinemia, transfusion of donor plasma is possible.
A feature of the treatment of pathology in adults is the simultaneous elimination of the provoking disease. In this case, the doctor should take into account all possible options for the interaction of drugs from different groups. During the period of remission, patients are recommended sanatorium treatment in regions with warm and dry climates.
Prognosis and prevention
With timely detection of lipoid nephrosis in a child and active treatment, the prognosis of the disease is relatively favorable. The duration of the course can reach 20 years, during the period of exacerbations, the patient temporarily loses his ability to work due to pronounced edema and concomitant disorders. With a secondary type of condition, the prognosis largely depends on the characteristics of the course of the provoking disease.
There is no specific prevention of nephrosis, it is recommended to fully treat diseases that can stimulate such kidney damage. Patients in the asymptomatic stage should follow a diet to prevent the development of an attack, avoid hypothermia and contact with sources of infections. It is necessary to undergo regular examination by a nephrologist with monitoring of protein levels in urine to prevent complications.