Membranous glomerulonephritis is a disease characterized by damage to the glomeruli of the nephron with the development of nephrotic syndrome and renal failure. At the initial stages, the course is asymptomatic, in the future there are pain in the lower back, oliguria, swelling of subcutaneous fat. Diagnosis is carried out through laboratory tests (general blood and urine tests, functional renal tests), ultrasound, histological examination of kidney tissues. Treatment includes taking ACE inhibitors, correction of rheological properties of blood, immunosuppressive therapy.
Meaning
Membranous glomerulonephritis (MG), or extramembranous nephropathy, is a fairly common condition. More than 40% of all cases of nephrotic syndrome in adults are caused by this pathology. According to various estimates of specialists in the field of practical urology, the proportion of MG among inflammatory kidney diseases ranges from 3 to 15%.
The vast majority of patients belong to the middle age group (20-35 years), only 1% of patients are children. Women and men are affected with approximately equal probability, however, glomerulonephritis occurs more easily in females, and complications are detected less often. Severe renal insufficiency develops slowly, is registered in about 40% of patients on average 15 years after diagnosis.
Causes
A clear relationship has been established between the development of membranous glomerulonephritis and the presence of a number of pathologies of various nature. At the same time, some cases of the disease occur for no apparent reason. With this in mind, there are primary (idiopathic) and secondary variants of the disease. The starting factors of the secondary form are the following circumstances:
- Infectious diseases. The most common cause of membranous nephropathy. Patients with this form of glomerulonephritis often have a history of episodes of viral hepatitis (B, C), tuberculosis, syphilis, schistosomiasis.
- Malignant neoplasms. Tumors can trigger a number of autoimmune reactions, including against kidney antigens. Especially often, membranous glomerulonephritis is observed in chronic lymphocytic leukemia, lung and intestinal cancer, and some lymphomas.
- Taking medications. Relatively rarely causes the development of the disease. Medications that can provoke pathology include NSAIDs, gold preparations, captopril, D-penicillamine.
The causes of idiopathic extramembranous nephropathy are still unknown. It is assumed that there are genetic abnormalities affecting some parts of the immune system, as a result of which there is a lesion of the membranes of the glomeruli of the nephron. Indirectly, this is confirmed by the more frequent detection in patients with MG of diabetes mellitus and other pathologies of autoimmune genesis – systemic lupus erythematosus, psoriasis.
Pathogenesis
With the development of membranous glomerulonephritis, an abnormal immune reaction to some glomerular proteins is observed. A specific antigen has not yet been identified, but it has been established that it is located mainly on the walls of capillaries and on the glomerular basement membrane. Due to the violation of immunity against these proteins, antibodies are produced, which accumulate in the nephron, forming immune complexes.
This leads to a thickening of the walls of the capillaries and the basement membrane, the diffusion of fluid through them is difficult. As a result, the glomerular filtration rate decreases, the functionality of the nephron decreases sharply. In the future, the affected glomeruli become unable to retain plasma proteins, which begin to pass into the urine and leave the body. Proteinuria with hypoalbuminemia and hyperlipidemia is noted.
The rheological properties of the blood deteriorate – its oncotic pressure decreases, as a result, swelling of the subcutaneous tissue occurs. As more and more nephrons are “turned off”, the excretory function of the kidneys begins to suffer, their insufficiency develops. In some patients at this stage, irritation of the juxtaglomerular apparatus is possible, leading to an increase in blood pressure.
Symptoms
Most often, the disease develops a few weeks after the infection, against the background of oncological pathology, after a long course of taking medications. Initially expressed symptoms are not determined – at this stage MG may be detected accidentally when performing a urine test. In the future, patients may complain of weakness, bruising, headaches, loss of appetite.
The skin becomes pale, some patients have fever attacks (up to 39-40 degrees) and arterial hypertension. Often these manifestations go unnoticed, are lost against the background of the symptoms of the underlying disease. With the progression of membranous glomerulonephritis, there is pain in the lower back, swelling of the tissues of the face, limbs. Puffiness is usually asymmetrical, soft to the touch, in rare cases the skin is tense. The daily excretion of urine decreases somewhat (oliguria), the urine becomes cloudy, a precipitate is easily formed in it. Sometimes there is an accumulation of fluid in the body cavities, an increase in the abdomen indicates ascites, cough and difficulty breathing – hydrothorax.
MG is characterized by spontaneous remissions with almost complete disappearance of symptoms, often followed by relapses. With a prolonged course of glomerulonephritis and frequent exacerbations, signs of chronic renal failure may appear. In addition to oliguria and edema, in such cases, the smell of ammonia from the skin and from the mouth is detected, confusion, fainting is possible. In severe cases, immunodeficiency also develops due to the loss of immunoglobulins in the urine.
Complications
The most common complication of membranous glomerulonephritis is renal failure due to the death and sclerosis of a large number of nephrons. The probability of such a condition is higher in men, people over 50 years of age and patients with massive proteinuria (over 15-20 g / day). Against the background of this nephropathy, other systemic pathologies may occur or worsen – SLE, psoriasis, autoimmune thyroiditis, diabetes mellitus. The risk of thrombotic complications increases – thrombosis of the renal vessels and deep veins of the lower extremities, pulmonary embolism. With the secondary nature of MG, due to impaired renal function, it may be difficult to treat the underlying disease – infection or tumor.
Diagnostics
The detection of membranous glomerulonephritis is carried out by a nephrologist, consultations of other specialists are often required – an immunologist, oncologist, phthisiologist, which is mainly due to the secondary nature of the pathology. Without a number of special studies, this nephropathy is difficult to distinguish from similar conditions – for example, lipoid nephrosis. The survey plan includes the following methods:
- Examination and anamnesis collection. In most cases, edema is detected in the face, neck and extremities, the skin is pale, dry. When questioned, patients complain of weakness, lower back pain, fatigue. In the anamnesis, infectious diseases are often detected or the patient is registered in an oncological dispensary.
- Laboratory tests. A general blood test reveals moderate leukocytosis and an increase in ESR, BAC – hypoalbuminemia, hyperlipidemia with a sharp increase in cholesterol, phospholipids and creatinine. Urine examination confirms proteinuria (up to 20-30 g / day), single leukocytes and erythrocytes can be determined.
- Histological examination. Microscopy of kidney tissues shows an increase in the thickness or doubling of the basal glomerular membrane, dystrophy of the tubule epithelium. Immunohistochemical examination reveals deposits of immune complexes in the glomerulus and in the tubules. Cellular proliferation of mesangium is absent or very poorly expressed.
- Ultrasound diagnostics. At the initial stages of the development of membranous glomerulonephritis, changes according to ultrasound of the kidneys are usually absent. With a prolonged course of pathology, an increase in the size of organs, a violation of the differentiation of the cerebral and cortical layer, the appearance of sclerotic processes is possible.
As part of the definition of nephropathy, other studies aimed at identifying the underlying disease can be prescribed, including a variety of serological, biochemical, radiological and other methods. Differential diagnosis is performed with lipoid nephrosis and other types of glomerulonephritis. A feature of MG that distinguishes it from these conditions is the presence of immune complexes on the nephron membrane with the simultaneous absence of cell proliferation.
Treatment
Most specialists are inclined to the need for immunosuppressive therapy. Etiotropic treatment of the disease, which acts as a predisposing factor, plays an important role. Symptomatic measures aimed at restoring the normal blood picture and improving the filtering ability of the kidneys are shown. The basic treatment program for membranous nephropathy includes the following components:
- Immunosuppressive therapy. Glucocorticosteroids are most often used – in high dosages during exacerbation and supportive during periods of remission. In severe cases (high proteinuria, increasing kidney failure) steroids are combined with alkylating cytostatic immunosuppressants.
- Acceleration of the GFR. Nephroprotectors are prescribed mainly from the group of ACE inhibitors. An additional effect when using them is the elimination of arterial hypertension of renal genesis, which sometimes occurs with MG.
- Infusion therapy. Patients need to restore the level of proteins in the blood, for this purpose, donor plasma transfusions can be carried out for severe patients. To reduce edema, if necessary, diuretics and electrolyte solutions are used.
General winter measures are carried out – during exacerbations, strict bed rest, a high-protein diet (to restore plasma proteins) are shown, fried or spicy dishes are excluded. It is necessary to limit the consumption of table salt (no more than 2 grams per day) – excessive amounts of it contribute to the preservation of edema and increase blood pressure. In the periods between exacerbations, resort treatment in specialized sanatoriums is recommended.
Prognosis and prevention
The prognosis of membranous glomerulonephritis is ambiguous, in some patients prolonged spontaneous remissions are recorded, while in others pathology leads to the development of CRF. According to statistics, the ten-year survival rate in the absence of treatment is 60-65%. The presence of concomitant diseases and complications – infections, oncological processes, autoimmune disorders – has a significant impact on the prospects of MG. With full-fledged complex therapy, long-term compensation of pathology is possible.
There is no specific prevention, it is recommended not to delay the treatment of diseases that can provoke kidney damage. Patients in remission should regularly visit a nephrologist to monitor their condition and detect complications in a timely manner.