The renal papillae are the areas of the kidney where the openings from the collecting ducts enter the renal pelvis. Necrosis (tissue death) of this area may may make the kidney unable to concentrate the urine. This causes polyuria (increased urine volume, usually in excess of 3 liters per day) and nocturia (frequent urination at night). The necrotic tissue may be sloughed off, and it may be seen in the urine, or the tissue may obstruct the renal pelvis or the ureter. Presence of necrotic tissue in the urine increases the risk of urinary tract infections. Necrosis of multiple papillae in the kidney can lead to failure of that kidney. Renal papillary necrosis is most commonly associated with analgesic nephropathy, diabetic nephropathy, renal transplant rejection, urinary tract obstruction, kidney infections and sickle cell anemia. Sickle cell anemia is a common cause of renal papillary necrosis in children.
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