Nephrotic syndrome is itself not a disease. It is a set of symptoms caused due to an underlying illness. The barrier of the glomerular capillary wall has permissible selectivity.

The glomerulus apparatus in the kidney through which the blood passes in a U path is the filtration apparatus.

Nephrotic Syndrome: Causes And Symptoms

There are millions of glomeruli in the glomerulus apparatus consisting of a mesh of tiny blood vessels and nerves. Injury, infection, or inflammation of the glomeruli impairs its filtration ability. (  

Nephrotic Syndrome: Causes And Symptoms

Nephrotic and Nephritic syndromes

Normal urine has trace protein contents and no RBC content. In normal health, kidneys retain essential substances for the body and pass out the waste products with the urine.

When the permissive selectivity of the glomerular capillary wall is hampered, larger molecules like protein and RBC also come out with the urine.

In this condition, essential substances pass out in urine more than normal amounts. The nephrotic syndrome arises when kidneys pass out too much protein, and nephritis syndrome arises when kidneys pass out red blood cells with the urine. 

Causes of nephrotic syndrome

Nephrotic syndrome is caused when tiny blood vessels in the glomerulus apparatus get damaged and lose their normal filtration ability. The damage can occur due to one or more of the following reasons:

  • Diabetic nephropathy

Uncontrolled blood sugar causes inflammation to delicate organs like the eyes and kidneys. Diabetic nephropathy is inflammation of the nephrons or kidney cells that can damage the glomeruli.

  • Minimal change disease 

This disease mostly occurs in children and is a common cause of nephrotic syndrome in children. In this disease, the kidney tissues appear normal, yet the kidney does not function normally and identifying the cause of the syndrome is difficult.

  • Glomeruli scarring

Scarring of glomeruli can damage glomeruli and change their selective permissibility to retain larger molecules. Scaring of glomeruli can be due to the presence of other diseases, CKDs, genetic diseases or certain medications.

  • Membrane thickening

The thickening of the glomeruli membrane can cause it to lose its normal selective filtration ability. Thickening of the glomeruli membrane can occur due to deposits made by the immune system. Lupus, malaria, hepatitis B or cancer can also cause the thickening of the glomeruli membrane. Sometimes the reason may not be apparent.

  • Chronic inflammatory disease

Chronic inflammatory disease like lupus, high blood sugar and other inflammatory conditions can damage the glomeruli.

  • Amyloid proteins accumulation

Accumulation of amyloid proteins in organs can damage kidney cells and their filtration ability.

  • Other infections and diseases

Bacterial infections and several infectious diseases can cause infection in the glomeruli and damage the filtering cells. Diseases like CKDs, diabetes, lupus, malaria, reflux nephropathy, amyloidosis can cause nephrotic syndromes. 

  • Adverse effects of medicines

Sometimes medicines can show side effects in some patients due to existing complexities or other reasons. Medicines for fighting microbes and non-steroidal anti-inflammatory medications are known to cause glomeruli damage and nephrotic syndrome in some cases.

  • Viral attack

Glomeruli tissues can succumb to viral attacks and lose their normal functionalities. The glomeruli can be adversely affected by viral infections like HIV, hepatitis B and hepatitis C.

Symptoms of nephrotic syndrome

Illness condition should be reported for medical diagnosis without delay when preliminary symptoms show up. Other symptoms like elevated protein levels are confirmed by urine and blood sample tests

Preliminary symptoms

Preliminary symptoms associated with nephrotic syndrome can show up as severe swelling, also called edema.

The swelling can occur around the eyes, ankles and feet due to excess fluid retention. In nephrotic syndrome condition, urine does not appear as its normal texture of clear pale yellow.

Extra protein in the urine makes it appear foamy. There is also a weight gain due to retention of excess fluids, loss of appetite, and fatigue.

Urine and blood sample test readings

The presence of the preliminary symptoms cannot be confirmatory. A blood and sample test is conducted to confirm the diagnosis.

Nephrotic syndrome is confirmed if the urine sample shows above normal protein levels. Blood sample also generally shows below normal protein levels due to excessive loss of proteins.

However, when protein levels fall, the liver starts producing more protein and releases albumin and cholesterol during the process. Due to this, the blood sample can show raised levels of cholesterol and albumin protein. Hence level of protein in the urine is considered an important indicator in paired tests.