Nephrotic syndrome is a kidney disorder characterized by protein in the urine, low protein levels in the blood, swelling, and high cholesterol levels. It is caused by damage to the glomeruli in the kidneys, which leads to increased permeability of proteins in the kidneys and their loss in the urine. Treatment involves medications like steroids to reduce protein in the urine, a low-sodium diet to control swelling, and monitoring for infections which patients are at higher risk for due to low immune function. Nursing care focuses on fluid management, preventing infections, providing emotional support, and educating patients and families on treatment and self-care at home.