I. Overview.
Pediatric nephrotic syndrome is a group of clinical syndromes caused by multiple etiologies of increased permeability of the glomerular filtration membrane to plasma proteins and loss of large amounts of plasma proteins from the urine, resulting in a series of pathophysiologic changes. Four major features of clinical manifestations are.
(i) massive proteinuria.
② hypoalbuminemia.
(iii) hyperlipidemia.
④Oedema of varying degrees.
The two conditions ① and ② are required.
This disease is a common kidney disease in children, and its incidence is second only to acute glomerulonephritis in pediatric kidney diseases. 1982, the statistical results of 105 hospitals in 20 provinces and cities in China, nephrotic syndrome accounted for 21% of the children hospitalized with urological diseases in the same period, of which 58.9% were first-time patients. In 1992, a similar survey was conducted in 24 provinces and cities. The disease accounted for 31% of children with internal urological diseases. There is an increasing trend compared with 1982. The incidence of the disease in black children seems to be slightly higher than that of white children, with an annual incidence of 2-7/100,000 new cases in the population under 16 years of age reported abroad.
II. Etiology and classification.
Although all pediatric nephrotic syndrome has the four major clinical manifestations mentioned above, it includes a variety of glomerular diseases with different etiologies and pathological changes, thus researchers have given classification or typing from different perspectives in order to guide clinical work and explore the nature of the disease.
Clinical classification: At present, according to the traditional viewpoint, the syndrome is divided into three categories, namely primary, secondary and congenital in our pediatric clinic.
1, primary nephrotic syndrome: refers to the disease whose etiology is unclear and whose primary lesion is in the glomerulus. In the process of primary glomerular disease, such as acute glomerulonephritis, acute nephritis, chronic glomerulonephritis, etc. can appear in the course of the disease NS. according to the domestic clinical classification can be divided into simple type (type I) and nephritis type (type II). The former only has the above-mentioned four characteristics of massive proteinuria, hypoproteinemia, hyperlipidemia and edema, while the latter has one or more of the following four manifestations in addition to the above four clinical manifestations.
① urine red blood cells >10/high magnification field (3 centrifugal urine tests within two weeks).
②Recurrent or persistent hypertension: >17.3/12.0kPa (130/90mmHg) in school-age children and >16.0/10.7kPa (120/80mmHg) in preschool children, and excluding corticosteroid use.
(iii) Azotemia: plasma urea nitrogen >10.7 mmol/L (30 mg/dl) and exclude those due to hypovolemia.
(iv) Recurrent reduction in total blood complement activity or complement C3. Clinically, type I is more common, according to our data analysis of 1462 hospitalized cases: 68.4% for type I and 31.6% for type II.
2.Secondary nephrotic syndrome: It refers to those secondary to systemic diseases (such as systemic lupus erythematosus), or with a clear etiology (such as infection). Its etiology is wide and complex, and only the more common ones in pediatric period are listed below.
(1) Systemic systemic diseases: systemic lupus erythematosus, allergic purpura, polyarteritis nodosa, mixed connective tissue disease, dermatomyositis, etc.
(2) Infections: bacterial infections: post-streptococcal nephritis, bacterial endocarditis, infectious nephritis by cardiac bypass, etc.; viral and other types of infections: hepatitis B, hepatitis C, cytomegalovirus, varicella and EBV; malaria, congenital or secondary syphilis, etc.
(3) Drugs or allergies: penicillamine, propofol, mercury, trimethoprim, captopril, non-steroidal anti-inflammatory drugs, interferon, serum and vaccination, etc.
(4) Family genetic diseases: Alport syndrome, A Bin syndrome and sickle cell anemia, etc.
(5) Metabolic diseases: diabetes mellitus, mucinous edema.
(6) Tumors: Wilms tumor, leukemia, Hodgkin’s lymphoma and multiple myeloma, etc.
(7) Other: chronic rejection reaction of renal transplantation, malignant glomerulosclerosis and renal artery stenosis, etc.
3, congenital nephrotic syndrome: often refers to Finnish and non-Finnish congenital nephropathy caused by genetic factors.
In 1990, Steffensen et al. classified congenital nephropathies within the first 3 months of life into five categories.
(1) Finnish-type congenital nephropathy: an autosomal recessive disorder.
(2) Diffuse tethered sclerosis: most often seen in term infants, with a familial propensity to develop the disease rapidly, and most die of renal failure before the age of 3 years. Most of the glomeruli are involved and the lumen of the glomerular capillaries is occluded with fibrosis.
(3) Childhood congenital nephropathy: It is more common in China and develops in children from 3 months to 3 years old, mostly in infants and children aged 1-3 years. The pathological types are diverse, such as microscopic lesions, focal glomerulosclerosis, proliferative nephritis (including diffuse, exudative, thylakoid, crescentic forms, focal, membranoproliferative, etc.), and glomerulosclerosis. The difference from the histology of primary nephropathy is that no immune deposits are visible in this thylakoid proliferative nephritis.
(4) Secondary congenital nephropathy: Most of them are secondary to syphilis infection, and the pathological type is thylakoid proliferative nephritis or membranous nephritis, with basement membrane thickening as the main abnormality. Both light and electron microscopy show subepithelial deposits (IgG, fibronectin). In those secondary to toxoplasmosis, the renal pathology is, in most cases, diffuse nephrosclerosis. In those with cytomegalic inclusion virus infection, renal pathology showed dilated proximal tubules, moderate proliferation of glomerular thylakoid cells and interstitial inflammatory reaction.
(5) Congenital nephropathy combined with other genetic disorders such as nail-patellar dysplasia (autosomal dominant disorder), genital anomalies and oculo-diaphragmatic-renal syndrome (companion recessive inheritance).
Pathological classification.
The common pathological types of NS in the pediatric period are classified as: microscopic lesions (MCNS), focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN), membranoproliferative glomerulonephritis (MPGN), intracapillary proliferative nephritis (EnPGN), and mesangial proliferative nephritis (MsPGN), and also include renal disease with IgA-IgG deposition and IgA-IgG deposition and IgM deposition nephritis. The proportion of various pathological types in primary NS has been reported inconsistently, probably due to the age of the patient at the time of kidney puncture, the origin of the case and the indication for puncture.