Causes of symptoms and symptoms of nephrotic syndrome

Of this disease is a series of clinical performance originated in massive proteinuria, plasma proteins in a large number of urine loss, leading to hypoproteinemia, thereby causing edema, hyperlipidemia, and other organ system complications.
Proteinuria (Proteinuria) normal glomerular capillary wall filtration barrier - that is, filtration membrane (including endothelial cells, basement membrane, epithelial cells and the hole film) limit through most of the protein, and thus the glomerular cysts The original urine protein concentration of only 0.01-0.1g / L. When the glomerular filtration membrane injury by immune or other pathogenic factors, the charge barrier and (or) aperture barrier weakened, plasma protein filtration increase, a significant increase in induced urinary protein. Small lesions, the charge barrier weakened physiological PH negatively charged low molecular weight (MW = 70000-150000) protein (mainly albumin) loss of urine; aperture barrier in non-minimal change involvement, high molecular weight (MW => 150000) proteins such as of IgM, α2-macroglobulin, fibrinogen, high-density lipoprotein is also leaking from the non-selective proteinuria.
Discovered in recent years NS when in addition to loss of plasma albumin, loss of other protein components, resulting in organ system dysfunction or complications. Carrier protein, such as trace elements are missing: like transferrin loss can cause iron deficiency anemia; zinc binding protein loss induced taste disorders in children, poor appetite, but also affect the thymosin synthesis and lymphocyte proliferation induced by cellular immune abnormalities. A variety of hormone binding protein loss: loss of 25 - hydroxy calciferol binding protein, caused by calcium metabolic disorders, reduction in intestinal calcium absorption, serum calcium decreased; thyroxine-binding protein is lost, causing the blood of the T3, T4, decreased thyroid dysfunction ; cortisol-binding protein decreased the elevated free cortisol in the blood, caused by abnormal cortisol metabolism. The loss of immunoglobulin, prone to cause a reduced ability of anti-infective. Prostaglandin-binding protein is lost, allow prostaglandin metabolic changes, and even affect the blood clots form. Antithrombin III is lost, easy to trigger a hypercoagulable state. Loss of lipoprotein lipase, it will affect the very low density lipoprotein and low density lipoprotein metabolism, and promote a form of hyperlipidemia.
Low albumin (hypoalbuminemia) is a direct consequence of massive proteinuria is low serum albumin, the disease is also the pathophysiology of the syndrome to change the main influencing factors. Environmental stability of its body and the metabolism of a variety of substances have a significant impact, when the serum albumin decreased to less than 25g / L, the plasma colloid osmotic pressure decreased significantly change the body of liquid distribution, a large number of intravascular fluid to the inter-organizational transfer caused by interstitial edema; at the same time caused the effective circulating blood volume decreased, resulting in the body a series of physiological and pathological changes. Such as nerve - endocrine system disorders; sodium and water retention; abnormal lipoprotein metabolism caused by hyperlipidemia; the formation of a hypercoagulable state.
Lost due to hypoalbuminemia mainly plasma protein in urine, but its lower degree of urinary protein is sometimes not completely consistent, so many scholars believe that may be associated with this disease, albumin insufficient synthesis and catabolism (renal tubular Office) to increase or extrarenal pathways (such as the loss of the gastrointestinal tract). Scholars note with urinary protein loss in this disease increase in liver protein synthesis, hepatic protein synthesis in normal daily 130-200mg/Kg 500mg/Kg compensatory increased synthesis rate and liver function related to, but also protein intake and calorie intake, when the amount of intake (daily protein 1.2-2.0g/Kg daily calorie 35Kcal/Kg) synthesis better. In NS often failed to show this compensatory effect may be related to the lack of children intake. About 5-12% of normal blood circulation to albumin catabolism in the kidney, intestine, liver and surrounding tissue, etc., about 10% of the total decomposition of renal local, animal experiments show that nephropathy in rats albumin catabolism was significantly increased. local kidney percentage of increase. Notwithstanding the report of gastrointestinal albumin loss in this syndrome, but failed to get the consensus of most scholars.
Hyperlipidemia (hyperlipidemia) Primary NS, more associated with hyperlipidemia, the higher the degree is often associated with the degree of proteinuria and serum albumin level, in addition to patients' age, diet, renal function status, corticosteroids The application of a variety of factors. Hyperlipidemia often reflected hyperlipoproteinemia, NS in children with blood cholesterol increased significantly, triglycerides different individuals or stage of disease vary, but persistent massive proteinuria and severe low serum albumin more than an increase in , early in the disease very low density lipoprotein (VLDL, the main carrier of triglycerides) and low-density lipoprotein (LDL, the main carrier of cholesterol) is increased. High-density lipoprotein (HDL) can be normal, reduced or increased. Also rely on at the drop of the plasma albumin level (Table 2-1-5) and the nature of the primary disease, the decline of of HDL2 than HDL3, and apolipoprotein in the urine is also increased.
NS when hyperlipidemia reason is more complex, may be associated with lipoprotein metabolism disorder, the first increased liver synthesis of lipoproteins, which is the Liver hypoalbuminemia and plasma osmolality caused by blood viscosity changes the reaction is not directly linked with liver albumin synthesis. Followed by decreased lipoprotein clearance rate decreased due to the activity of the enzyme, such as lipoprotein lipase (can be cleared in VLDL triglyceride) activity decreased by 30-60%, lecithin turn acyl enzyme (catalytic cholesterol esterification) activity due to hypoproteinemia and reduced, and the enzyme is lost in the urine.
Adverse effects of hyperlipidemia on the body: ① glomerular filter out the toxic effects of lipoprotein in mesangial cells, may lead to glomerular sclerosis; ② increased platelet aggregation, may trigger a hypercoagulable and thromboembolism complications; ③ long hyperlipidemia, especially LDL rise and HDL decreased, can produce atherosclerosis. However, minimal change disease urinary loss of HDL, less than other non-minimal change nephrotic HDL so the blood is relatively high, and thus atherosclerotic cardiovascular complications are rare.
Edema (edema) are common symptoms of NS sick child, and its mechanism, the traditional view that the large number of urinary protein loss, decreased serum albumin concentration, resulting in lower plasma colloid osmotic pressure and intravascular fluid leakage into the interstitial space, plasma volume decreased enable the body to retain water capacity and pressure receptors, sodium-related neurohumoral factors are activated: If prompted sympathetic nerve release of catecholamines, renin - angiotensin - aldosterone system activity, secondary to inappropriate antidiuretic hormone secretion increased natriuretic factor is inhibited, resulting in a body of water, sodium retention and edema. This theory emphasizes that the volume fell to this mechanism, it is known as filling the lack of doctrine (underfilling theory). But in recent years some scholars have observed to NS when not accompanied by decreased blood volume, plasma renin - angiotensin levels may not necessarily be increased, it is proposed that the intrinsic primary water and sodium retention, rather than blood The decrease in the capacity to stay due to the primary water and sodium retention can lead to blood volume expansion, in contrast to the above theory, it is also known as the doctrine of over-filling (overfilled theory). In fact the mechanism of NS in edema magazine may be a combination of factors, and different patients with different diseases of the mechanism may vary.