Nephrotic syndrome (NS) is a non-specific kidney disease characterized by the body excreting too much protein into the urine. It is non-specific because it can be caused by various disorders that damage the kidney. The excess protein in urine comes from the protein that is normally kept in the bloodstream. Protein in the bloodstream helps to control fluids in the bloodstream. Without enough protein in the blood, the fluids can leak out of the bloodstream and cause swellings in different areas of the body, commonly in the legs and the eyes. Additionally, NS can lead to weight gain as the uncontrolled fluids are retained in the body.
The most common cause of NS in children is minimal change disease. Minimal change disease is when the glomeruli, the filtering units that make urine and remove waste, are damaged. While the cause is relatively unknown, it is suggested that immune related conditions such as allergic reactions, vaccinations, and viral infections can cause the disease.