1. A childhood kidney disease in which there is progressive symmetrical destruction of the kidneys involving both the tubules and glomeruli, characteristically resulting in anemia, polyuria, polydipsia, isosthenuria (decreased ability to concentrate the urine), progressive renal failure and death in uremia.

The chronic kidney failure affects growth and leads to short stature. The age at death ranges from around four to fifteen years.

2. Etymology: derived from nephron + phthisis.

The nephron is the fundamental functional unit in the kidney and includes the renal tubule and glomerulus. Phthisis is a Greek word meaning "a dwindling or wasting away".