Nephrotic syndrome is a kidney disorder characterized by heavy protein in the urine, low blood protein levels, fluid retention causing edema, and high cholesterol. It is caused by damage to the glomeruli in the kidneys, which allows protein to pass into the urine. Common causes include infections, cancers, autoimmune diseases, medications, and genetic factors. Symptoms include generalized edema, fatigue, loss of appetite, and shortness of breath. Diagnosis involves blood and urine tests to detect low protein and high protein in the urine. Treatment focuses on reducing edema with diuretics, lowering blood pressure and proteinuria with ACE inhibitors, and using steroids to reduce inflammation in some cases.