In childhood nephrotic syndrome, the kidneys leak protein, causing body swelling and a variety of possible complications such as infection, blood clots, and kidney failure. The first-line treatment for nephrotic syndrome is corticosteroids. Many children respond to prednisone treatment, but the disease comes back (relapses) when the prednisone is stopped or the dose is reduced. Children with frequently relapsing or steroid dependent nephrotic syndrome are at risk for toxicity from frequent exposure to corticosteroids.