Nephrotic syndrome has four main features, namely, proteinuria, hypoalbuminemia, hypercholesterolemia, and systemic significant edema.
1 proteinuria proteinuria is a sign of nephrotic syndrome. Albumin is the main component, also contain other plasma protein components. Glomerular basement membrane permeability changes is the basic cause of proteinuria generated charge barrier and mechanical barrier (glomerular capillary pore barrier) changes and catabolic ability reabsorption in renal tubular epithelial cells in the formation of proteinuria also have an impact. Glomerular filtration rate, plasma protein concentration and protein intake directly affect the degree of proteinuria. Glomerular filtration rate, proteinuria will reduce; severe hypoalbuminemia, increase urinary protein excretion, urinary protein excretion high protein diet will increase; therefore, only quantitative methods protein a day, can not accurately determine the extent of urinary protein, albumin clearance rate can be further done, urine protein / creatinine (> 3.5 often nephrotic range proteinuria). Urine protein electrophoresis detected in urine IgG components increased urinary protein prompted low selectivity. No definite clinical value of urinary protein selectivity, has been seldom used.
2 hypoalbuminemia is the second essential characteristic of nephrotic syndrome. Serum albumin of less than 30g / L. When nephrotic syndrome liver albumin synthesis increased when the diet given adequate protein and calories, the patient's liver synthesis of albumin day about 22.6g, 15.6g significantly more than normal every day. When the liver synthesis of albumin compensatory insufficient to cover the amount of urinary protein loss, hypoalbuminemia appear. Is incomplete agreement between hypoalbuminemia and urinary protein excretion.
Nephrotic syndrome usually in negative nitrogen balance, in the high protein load, may be turned into a positive nitrogen balance, high protein load may be due to an increase in glomerular filtration protein leaving the urinary protein excretion increased, so the plasma protein concentration is not obvious, but while taking blood angiotensin converting enzyme inhibitors, can inhibit the excretion of urinary protein, serum albumin concentration can be increased significantly.
It is worth noting that, when hypoalbuminemia, drug Albumin be reduced, free drug concentration in the blood may increase the toxicity of the drug.
Variety of plasma protein components change nephrotic syndrome can occur when, α2 and β globin increased, α1-globulin were normal. IgG levels were significantly decreased, while IgA, IgM, IgE levels were normal or elevated, fibrinogen, coagulation factor Ⅴ, Ⅶ, Ⅷ, Ⅹ can be increased, which may be related to elevated liver synthesis, increasing the number associated with platelet, anticoagulant blood enzyme Ⅲ (heparin-related factor) lower, C protein and S protein concentrations were normal or increased, but decreased activity. This will contribute to the occurrence of a hypercoagulable state. Increased urinary fibrin degradation products (FDP), reflecting changes in glomerular permeability. In short, blood coagulation and aggregation of various pre-exponential factor were increased, while the anti-coagulation and fibrinolysis mechanism of damage. Due to the combined effects of hypercholesterolemia and hyperfibrinogenemia, and plasma viscosity increase, when endothelial damage, prone to spontaneous thrombosis.
In addition, the transport protein is also reduced, such as carrying an important metal ion (copper, iron, zinc) protein decreased, and the important hormones (thyroxine, cortisol, prostaglandins) and active 25- (OH) D3 binding proteins also drop, which can lead to secondary hyperparathyroidism, calcium and phosphorus metabolism, causing renal osteodystrophy. Continuing transferrin reduced to glucocorticoid treatment in the human body by free and bound hormone ratio change, resulting in drug metabolism and efficacy change.
3 hyperlipidemia this disease, total cholesterol, triglycerides increased significantly, low-density lipoprotein (LDH), elevated very low density lipoprotein (VLDH) levels. Hyperlipidemia and hypoalbuminemia concerned, LDL / HLDL only serum albumin less than 10 ~ 20g / L only increased. High density lipoprotein (HDL) normal or decreased. LDL / HDL ratio increased, so that the risk of atherosclerotic complications increases, hyperlipidemia and thrombosis and progressive glomerular sclerosis.
Patients showed a lipid urine, double refraction of the fat body in urine appears likely to epithelial cells containing cholesterol or fat body casts.
4 edema most notable symptom is gradually worsening edema, initial early morning eyelids, face, visible ankle edema; With the progression of the disease spread to the whole body edema and pleural effusion, ascites, pericardial effusion, mediastinal effusion, scrotum or labia edema, pulmonary edema can occur. In severe cases, can not open his eyes, head and neck thicker, waxy pale skin can be presented, in addition to the chest, the presence of ascites, it is obvious difficulty in breathing, you can not only sit supine position. If skin damage, the tissue fluid spill and difficult to stop. Edema and postural relationship obviously, if there has nothing to do with the position of edema and venous thrombosis should be suspected. The severity and extent of edema generally hypoalbuminemia were positively correlated. Generally considered edema caused mainly by heavy proteinuria plasma proteins (especially albumin) decreased plasma colloid osmotic pressure reduced intravascular to the interstitial space due to moving water. Otherwise considered intrinsic edema associated with primary renal sodium and water retention, which may factor is: ① glomerular filtration rate; ② increased tubular reabsorption; ③ distal tubule plasma atrial natriuretic peptide (ANP) reaction ability.
