Kidneys affected by nephrotic syndrome have small pores in the podocytes, large enough to permit proteinuria (and subsequently hypoalbuminemia, because some of the protein albumin has gone from the blood to the urine) but not large enough to allow cells through (hence no hematuria). By contrast, in nephritic syndrome, RBCs pass through the pores, causing hematuria.
According to NephCure, most often, Nephrotic Syndrome is defined by its primary diseases that attack the kidney’s filtering system. Some of these cases are idiopathic.
Signs and symptoms
It is characterized by proteinuria (>3.5g/day), hypoalbuminemia, hyperlipidemia and edema which is generalized & also known as anasarca or dropsy. Common among 2–6 years old boys. The edema begins in the face. Lipiduria (lipids in urine) can also occur, but is not essential for the diagnosis of nephrotic syndrome. Hyponatremia also occurs with a low fractional sodium excretion.
Hyperlipidemia is caused by two factors:
- Hypoproteinemia stimulates protein synthesis in the liver, resulting in the overproduction of lipoproteins.
- Lipid catabolism is decreased due to lower levels of lipoprotein lipase, the main enzyme involved in lipoprotein breakdown.
1 The most common sign is excess fluid in the body due to the serum hypoalbuminemia. Lower serum oncotic pressure causes fluid to accumulate in the interstitial tissues. Sodium and water retention aggravate the edema. This may take several forms:
- Puffiness around the eyes, characteristically in the morning.
- Pitting edema over the legs.
- Fluid in the pleural cavity causing pleural effusion. More commonly associated with excess fluid is pulmonary edema.
- Fluid in the peritoneal cavity causing ascites.
- Generalized edema throughout the body known as anasarca.
3 Anemia (iron resistant microcytic hypochromic type) maybe present due to transferrin loss.
4 Dyspnea maybe present due to pleural effusion or due to diaphragmatic compression with ascites.
5 Erythrocyte sedimentation rate is increased due to increased fibrinogen & other plasma contents.
6 Some patients may notice foamy or frothy urine, due to a lowering of the surface tension by the severe proteinuria. Actual urinary complaints such as hematuria or oliguria are uncommon, though these are seen commonly in nephritic syndrome.
7 May have features of the underlying cause, such as the rash associated with systemic lupus erythematosus, or the neuropathy associated with diabetes.
8 Examination should also exclude other causes of gross edema—especially the cardiovascular and hepatic system.