Nephrotic syndrome

Introduction "Nephrotic syndrome" (NS) referred to as renal syndrome, is caused by a variety of causes, with increased glomerular basement membrane permeability and decreased glomerular filtration rate and other glomerular lesions. The main group of syndromes. Clinically has four major characteristics: 1 large amount of proteinuria, more than 3.5g / d, may have lipid urine; 2 hypoalbuminemia, serum albumin less than 30g / L; 3 hyperlipidemia; 4 edema. The first two are essential conditions, and a large amount of proteinuria is the most basic feature of the disease. In the case of severe hypoalbuminemia, the amount of urinary protein excretion often decreases, which may not meet the above criteria, and attention should be paid when diagnosing.

Cause

Etiology classification

(a) primary nephrotic syndrome

According to domestic clinical classification: acute glomerulonephritis, rapid glomerulonephritis, chronic nephritis (common type, hypertension type, nephrotic syndrome type, acute onset of chronic nephritis), glomerular nephropathy. All of the above types can occur in the form of nephrotic syndrome. Pathologically divided: minimal lesion, focal glomerular sclerosis, membrane type. Membrane proliferative type, semilunar type, mesangial proliferation type. According to the discussion of the Second National Conference on Nephrology, the primary nephrotic syndrome was divided into type I and type II. The former had no persistent hypertension, and the urinary red blood cells were <10/high power field without persistent renal damage. Selective proteinuria, the protein in the urine is mostly albumin, sensitive to hormone therapy, and has a good prognosis; the latter often has hypertension, hematuria, renal insufficiency, proteinuria is non-selective proteinuria, and urine FDP and C3 are positive, and glucocorticoid treatment is partially effective. Whether it is clinical classification or pathological classification, each type can be transformed into each other. For example, acute nephritis can develop into chronic nephritis. Chronic nephritis can develop into nephrotic syndrome type, hypertension type, type I nephrotic syndrome can develop into Type II nephrotic syndrome, even pathological types can be converted to another pathological type.

(B) secondary nephrotic syndrome

Nephrotic syndrome secondary to systemic diseases, the causes are wide and complex and are summarized as follows:

1. Infectious diseases: viral infections such as hepatitis B virus-associated nephritis, mumps with nephritis, Coxsackie virus, and megavirus infection can affect the kidneys. Bacterial infections such as streptococci, staphylococcus, pneumococci, and salmonella. Protozoal infections such as Plasmodium are more common in three-day malaria, schistosomiasis, filariasis and the like.

2. Autoimmune disease: is a group of connective tissue diseases, the most common are systemic lupus erythematosus, dermatomyositis, nodular polyarteritis, Sjogren's syndrome, scleroderma, autoimmune capillary vasculitis, rheumatoid Arthritis, allergic purple, herpes dermatitis.

3. Allergic: such as snake bites, bee stings, pollen, serum. Vaccines and allergies to various drugs.

4. Metabolic diseases: such as diabetic nephropathy, amyloidosis, gout kidney, jaundice, and fluid edema.

5. Nephrotoxic substance damage: damage caused by mercury, gold, lead, arsenic, etc.

6. Tumors: such as Hodgkin's disease, lymphoma, multiple myeloma, chronic lymphocytic leukemia, colon cancer, lung cancer, breast cancer. Gastric cancer, etc.

7. Others: pregnancy-induced hypertension syndrome, renal artery stenosis, renal vein thrombosis, reflux disease, renal transplant rejection, heart failure and constrictive pericarditis.

(3) Congenital and hereditary diseases

Such as hereditary nephritis (also known as lport syndrome) congenital glomerular basement membrane ultrathin nephritis.

Mechanism

The damage of the glomerular filtration membrane (endothelial cells, basement membrane, epithelial cells and fissure membrane, collectively referred to as filtration membrane) is the pathological basis of nephrotic syndrome. The exact cause of the filtration membrane damage is unclear. It has been suggested that nephrotic syndrome caused by pathogenic microbial infection may be associated with immune dysfunction. Bacterium and its metabolites enter the human body as a hapten to form a complete antigen with the in vivo protein, causing an antigen-antibody reaction, forming an immune complex deposited on the glomerular filtration membrane, thickening the filtration membrane, and increasing the fissure. Increased permeability, protein leakage, but how the cellular immune humoral immunity changes in the occurrence of disease, how to combine with kidney tissue is still unclear, and the vast majority of clinical nephrotic syndrome is caused by non-infectious factors, how do these patients cause filtration? Membrane damage has not been known so far. In addition to the anatomical damage of the glomerular filtration membrane, the destruction of the charge barrier function and the production of proteinuria are also important reasons. Under normal conditions, each layer of the membrane is negatively charged, and when the glomerular disease is reduced, the negative charge is reduced or lost, allowing the negatively charged protein to leak out.

Due to the loss of a large amount of proteinuria, total plasma protein is reduced, especially albumin is more pronounced, colloid osmotic pressure is decreased, and patients often have severe edema. Decreased renal drainage and sodium discharge is also one of the causes of edema.

Increased cholesterol, phospholipids, and triglycerides in nephrotic syndrome. Hyperlipidemia is inversely associated with plasma albumin. In hypoproteinemia, albumin synthesis increases in the liver and lipoprotein synthesis also increases, so hyperlipidemia generally exists. In addition, lipid dysfunction is also one of the causes of hyperlipidemia.

an examination

Related inspection

Urine Peripheral Protein (BJP) Serum Creatinine (Cr, Crea) Serum Globulin (G, GL0) Renal MRI Check Protein Index (SPI)

Laboratory inspection:

1. Urine routine: simple kidney disease, urine protein 24h quantitative more than 0.1g / kg, occasionally a small amount of red blood cells. In addition to different degrees of proteinuria, nephritic nephropathy can also be seen under the microscope or gross hematuria.

2. Blood biochemical assay: manifested as hypoproteinemia (serum albumin <30g / L, infant <25g / L), albumin and globulin ratio inverted, serum protein electrophoresis showed increased globulin; blood cholesterol significantly increased (children >5.7 mmol/L, infant >5.1 mmol/L).

3. Determination of renal function: Temporary mild azotemia may be present during oliguria, and renal function is simple in simple nephropathy. If there is a different degree of renal insufficiency, an increase in serum creatinine and urea nitrogen is present, suggesting nephritic nephropathy.

4. Serum complement determination: It is helpful to distinguish between simple nephropathy and nephritic nephropathy. The former has normal serum complement, while the latter often has different degrees of hypocomplementemia and C3.

5. Serum and urine protein electrophoresis: by detecting urinary IgG component to reflect the selectivity of urinary protein, and at the same time identifying pseudo-mass proteinuria and light-chain proteinuria. If the ratio of gamma globulin to albumin in urine is less than 0.1, then For selective proteinuria (prompted for simple nephropathy), greater than 0.5 is non-selective proteinuria (prompted for nephritic nephropathy).

6. Serum immunological examination: detection of anti-nuclear antibodies, anti-double-stranded DNA antibodies, anti-Sm antibodies, anti-RNP antibodies, anti-histone antibodies, hepatitis B virus markers and rheumatoid factors, circulating immune complexes, etc., to distinguish the primary Sexual and secondary nephrotic syndrome.

7. Detection of blood coagulation and fibrinolysis-related proteins: such as fibrinogen and factors V, VII, VIII and X, antithrombin III, urinary fibrin degradation products (FDP), etc. can reflect the body's coagulation status Provide a basis for taking anticoagulant therapy.

8. Urine enzyme measurement: Determination of lysozyme, N-acetyl--glucosaminidase (NAG), etc., helps to determine whether there is renal tubular-interstitial damage.

Other auxiliary inspections:

1. B-ultrasound imaging examination: exclude congenital malformations of the kidney.

2. Percutaneous renal biopsy: For patients with poor diagnosis of nephritic nephropathy or glucocorticoid therapy, renal biopsy should be performed promptly to further define the pathological type to guide the formulation of the treatment plan.

Differential diagnosis

The diagnosis should be differentiated from the following symptoms:

1. Diffuse renal disease: Diffuse renal disease is a manifestation of kidney damage caused by various kidney diseases.

2. Renal ischemia: Renal ischemia is one of the causes of acute renal failure. Hyperosmoticity leads to renal ischemia and hypoxia. Because the general contrast agent is hyperosmotic, the concentration is 1400-1800 mOsm/L, and its iodine content is as high as 37%. When the hypertonic contrast agent reaches the kidney, it can be Causes renal vasoconstriction, reduced renal blood flow, leading to renal ischemia.

3. Renal interstitial edema: Renal interstitial refers to the connective tissue, nerves, blood vessels and lymphatic vessels in the kidney, distributed between the nephron and the collecting tubule. Excessive body fluids accumulate in the interstitial space or body cavity called edema. Renal interstitial edema refers to the accumulation of excessive body fluids in the renal interstitium.

4. Post-renal renal failure: The main cause of post-renal renal failure is urinary tract obstruction and urinary reflux.

Acute renal failure (ARF) can be divided into pre-renal, post-renal and renal. The disease and damage of the kidney itself is called renal renal failure. Prerenal renal failure is often caused by decreased blood pressure and renal hypoperfusion due to heart failure or other causes. The main causes of post-renal renal failure are urinary tract obstruction and urinary reflux.

Prerenal and post-renal, if diagnosed early, may be reversed. Some renal causes of acute glomerular vascular and tubulointerstitial nephropathy, such as malignant hypertension, glomerulonephritis, vasculitis, bacterial infections, drug reactions, and metabolic disorders (such as hypercalcemia, hyperuricemia) Hemorrhage) is also treatable.

diagnosis:

The diagnosis of nephrotic syndrome is based on the clinical manifestations of massive proteinuria, hypoproteinemia, hyperlipidemia, and high edema. Further diagnosis of type I and type II should be noted when diagnosing primary nephrotic syndrome. In the diagnosis of secondary nephrotic syndrome, the primary disease should be further diagnosed. Only when the primary disease is diagnosed, the treatment can be effective, such as the diagnosis and treatment of diabetes, the diagnosis and treatment of hepatitis, the diagnosis and treatment of tumor, and the diagnosis of parasitic diseases. Treatment, etc. Laboratory tests, in addition to the examination of nephrotic syndrome, should be based on different causes of selective laboratory tests, such as blood sugar, urine sugar examination, parasite examination, blood uric acid examination, lupus erythematosus examination, etc., in order to The onset is diagnosed. Primary and secondary, type I and type II diagnosis must be distinguished by kidney biopsy.

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