Glomerular disease
Summary/Definition
Glomerular disease, also known as glomerulonephritis, is a condition characterized by inflammatory processes in the glomerulus of the kidney due to impaired immune function. This disease leads to the development of symptoms and clinical signs in response to inflammation that occurs in the glomerular structure of the kidney. Glomerular diseases cause damage to the glomeruli, which play a key role in blood filtration and urine production. One of the most common types of glomerular diseases is glomerulosclerosis, in which the glomerular structure is destroyed and their function is reduced. This process can have different reasons. Collectively, all these diseases are called glomerular diseases. The causes of glomerular diseases can be diverse, and include factors such as diabetes and high blood pressure. In addition, infections, autoimmune diseases, side effects from taking medications, as well as genetic factors can contribute to the development of glomerular diseases. Since the causes of glomerular diseases can be diverse, it is important to correctly identify the underlying disease.
Glomerular diseases can be divided into primary and secondary, depending on their source. Primary glomerular diseases occur directly due to pathological processes that affect the kidneys themselves. Secondary glomerular diseases, on the contrary, arise as a consequence of problems in other organs, with the exception of the kidneys. Examples of primary glomerular diseases include conditions such as IgA nephritis, membranous glomerulonephritis, nephrotic syndrome of minimal changes, focal segmental glomerulosclerosis and membranoproliferative glomerulonephritis. Secondary glomerular diseases can be caused by a variety of conditions, for example, lupus nephritis, diabetic nephropathy, hypertensive nephropathy, infectious glomerular diseases, Schenlein-Genoch purpura, vasculitis associated with antineutrophil cytoplasmic antibodies, as well as abnormal glomerular conditions associated with protein disorders.
Glomerular diseases can be caused by a variety of reasons. Typical examples are genetic abnormalities, infections, exposure to toxic substances, autoimmune diseases, atherosclerosis, high blood pressure, embolism and thrombosis, as well as diabetes. However, there are cases when the cause cannot be determined, despite all efforts. Such cases are classified as idiopathic. It is believed that the autoimmune process is the most likely cause of most idiopathic glomerular diseases. Moreover, glomerular diseases can occur as a result of damage to the glomeruli by various mechanisms, and often several mechanisms may be involved in the same disease. These mechanisms include both immunological and non-immunological factors. It is believed that damage caused by immunological mechanisms is the cause of most primary glomerular diseases, and a typical example of immunological mechanisms is damage caused by antibodies. Non-immunological mechanisms may include metabolic disorders (for example, in diabetes), hemodynamic disorders (associated with hypertension, etc.), toxic effects, damage by deposition of abnormal proteins and damage caused by genetic abnormalities.
Symptoms
Symptoms vary and depend on the specific type of glomerular disease, but typical signs and symptoms include proteinuria, hematuria, edema caused by salt and fluid retention in the body, high blood pressure and deterioration of kidney function.
- Asymptomatic urination disorders
- This is a condition accompanied by proteinuria or hematuria (according to the results of a urine test, in which the patient does not experience any symptoms. It is most often detected during school or preventive medical examinations.
- This is a condition accompanied by proteinuria or hematuria (according to the results of a urine test, in which the patient does not experience any symptoms. It is most often detected during school or preventive medical examinations.
- Acute nephritis syndrome
- This syndrome is characterized by sudden hematuria, edema, increased blood pressure, a change in the color of urine (it can become the color of cola) and the presence of foam in the urine. Additional symptoms may be excessive proteinuria and decreased kidney function. This syndrome is often found in patients with IgA nephritis, which is the most common primary glomerular disease in Korea.
- This syndrome is characterized by sudden hematuria, edema, increased blood pressure, a change in the color of urine (it can become the color of cola) and the presence of foam in the urine. Additional symptoms may be excessive proteinuria and decreased kidney function. This syndrome is often found in patients with IgA nephritis, which is the most common primary glomerular disease in Korea.
- Nephrotic syndrome
- This syndrome is characterized by excessive proteinuria, hypoalbuminemia, extensive systemic edema and severe dyslipidemia. Sometimes nephrotic syndrome is accompanied by hematuria, and sometimes it is not observed. As a result of excessive excretion of protein in the urine, its concentration in the blood decreases, which leads to edema. Glomerular diseases that can manifest as nephrotic syndrome include microscopic nephrotic syndrome, focal segmental glomerulosclerosis and membranous glomerulonephritis.
- This syndrome is characterized by excessive proteinuria, hypoalbuminemia, extensive systemic edema and severe dyslipidemia. Sometimes nephrotic syndrome is accompanied by hematuria, and sometimes it is not observed. As a result of excessive excretion of protein in the urine, its concentration in the blood decreases, which leads to edema. Glomerular diseases that can manifest as nephrotic syndrome include microscopic nephrotic syndrome, focal segmental glomerulosclerosis and membranous glomerulonephritis.
- Rapidly progressive glomerulonephritis
- This condition is characterized by a sharp and rapid decrease in kidney function, which occurs within a few weeks or months. In some cases, it may be accompanied by proteinuria or hematuria and a possible increase in blood pressure, but the latter often goes unnoticed. Such cases are often associated with systemic vasculitis and may manifest systemic symptoms such as general malaise, fatigue and weight loss. It is important to note that there is often a significant decrease in kidney function, but most cases are not accompanied by atrophy of the renal parenchyma, as it develops quite quickly. Such conditions are often found in cases of glomerular diseases associated with systemic vasculitis, for example, in the syndrome of antibodies to the basement membrane and vasculitis associated with antineutrophil cytoplasmic antibodies (ANCA). For an accurate diagnosis and assessment of the severity of the disease, a kidney biopsy is often necessary, although in some cases the diagnosis can be confirmed by the results of a blood test without a biopsy.
- This condition is characterized by a sharp and rapid decrease in kidney function, which occurs within a few weeks or months. In some cases, it may be accompanied by proteinuria or hematuria and a possible increase in blood pressure, but the latter often goes unnoticed. Such cases are often associated with systemic vasculitis and may manifest systemic symptoms such as general malaise, fatigue and weight loss. It is important to note that there is often a significant decrease in kidney function, but most cases are not accompanied by atrophy of the renal parenchyma, as it develops quite quickly. Such conditions are often found in cases of glomerular diseases associated with systemic vasculitis, for example, in the syndrome of antibodies to the basement membrane and vasculitis associated with antineutrophil cytoplasmic antibodies (ANCA). For an accurate diagnosis and assessment of the severity of the disease, a kidney biopsy is often necessary, although in some cases the diagnosis can be confirmed by the results of a blood test without a biopsy.
- Chronic glomerulonephritis
- This is a glomerular disease that is often diagnosed in the late stages, when kidney function has already deteriorated significantly. The main feature of this condition is the absence of pronounced symptoms, despite the presence of proteinuria or hematuria. However, the level of proteinuria is usually not high enough to cause visible swelling or significant hematuria that could be detected with the naked eye. This disease is most often detected at the chronic stage, rather than at the acute stage, and for this reason, kidney biopsies often reveal chronic changes, rather than acute inflammatory lesions.
Diagnostics
The diagnosis of glomerular disease is made by a comprehensive interpretation of clinical features, the results of blood and urine tests, as well as pathoanatomic data and confirmed results of a kidney biopsy to make a final diagnosis. Particular attention is paid to a comprehensive analysis of the patient’s clinical symptoms, laboratory results and histological data. Based on the patient’s symptoms and laboratory data, the disease can be divided into five clinical syndromes: asymptomatic abnormalities in urine tests, acute nephritis syndrome, nephrotic syndrome, rapidly progressive glomerulonephritis and chronic glomerulonephritis. Although blood and urine tests can provide information about secondary glomerular changes, the final and accurate diagnosis is made based on the results of a kidney biopsy after receiving kidney tissue samples. At the same time, a kidney biopsy, unlike a conventional biopsy, is examined using three types of microscopy: optical, fluorescence and electron microscopy, which makes it possible to establish a definitive diagnosis.
<Table: Diagnostics and analyses>
| Optical Microscope | Fluorescent microscope | Electron microscope | |
| IgA jade | Mesangial cell proliferation and matrix expansion | Mesangial IgA positive | Deposition of electron-dense material in mesangia |
| Membranous glomerulonephritis | Thickening of the glomerular basement membrane | Granular IgG staining along the glomerular basement membrane | Extensive deposition of electron-dense material in sub-cells |
| Minor changes in nephrotic syndrome | Without pathologies | Unpainted | Diffuse loss of foot processes of podocytes |
| Focal segmental glomerulosclerosis | Segmental glomerular sclerosis | Unpainted | Diffuse loss of foot processes of podocytes |
| Diabetic nephropathy | Thickening of the glomerular basement membrane, mesangial expansion and nodular glomerulosclerosis. | IgG along the basement membrane of the glomeruli is weakly stained with glandular | Thickening of the glomerular basement membrane, enlargement of the mesangial matrix |
Treatment and course of the disease
Glomerular diseases vary greatly depending on the specific diagnosis, and even for the same disease, the treatment strategy may vary depending on its cause and severity. Therefore, accurate diagnosis of glomerular pathology and differentiation of its cause is very important. For example, the treatment of IgA nephritis varies depending on the cause. If IgA nephritis has developed against the background of a systemic disease, then treatment implies a complex effect on the source of the disease in combination with conservative kidney therapy. In the case of primary IgA nephritis, while maintaining normal kidney function, normal blood pressure and proteinuria of less than 1 g per day, conservative treatment is used, including RAS (renin-angiotensin system) inhibitors, which contribute to the maximum reduction of proteinuria. If the patient has primary IgA nephritis and proteinuria of more than 1 g per day persists despite maximal conservative treatment for more than 3 to 6 months, steroids may be used. In cases of primary IgA nephritis and clinical signs of rapidly progressing glomerulonephritis, treatment with steroids alone is difficult and may require the same treatment as with vasculitis. Even with the same disease, treatment tactics may vary depending on the cause, severity and activity of the disease, so the decision on treatment tactics should be made after a thorough discussion of the patient’s condition with the attending physician.
