Most people have one kidney on either side of their spines (in their lower back). Common kidney conditions include kidney disease, kidney infections and kidney cysts. Kidney Disease: There are several types of acute kidney problems and chronic kidney diseases leading to kidney failure. Learn more in this guide. Overview of the internal and external structure of the kidneys. The kidneys are bilateral organs placed retroperitoneally in the upper left and right abdominal quadrants and are part of the urinary system. Kidney, in vertebrates and some invertebrates, organ that maintains water balance and expels metabolic wastes. Primitive and embryonic kidneys consist of two series of specialized tubules that empty into two collecting ducts, the Wolffian ducts (see Wolffian duct). Your kidneys provide a vital function for your body to filter blood and produce urine. Pain in your upper abdomen or back and sides is also called flank pain or kidney pain. Flank pain can sometimes be an indication of a kidney infection or urinary tract infection. Kidney stones are also a common cause of kidney pain that is felt in the middle. Learn about kidney failure symptoms, tests, diagnosis and treatment options, including medicine, dialysis and kidney transplant. Learn about common signs and symptoms of kidney disease and what they may mean for your health. In the nephron, your blood is filtered by the tiny blood vessels of the glomeruli and then flows out of your kidney through the renal vein. Your blood circulates through your kidneys many times a day. In a single day, your kidneys filter about 150 quarts of blood. 37 million people in the U.S. have kidney disease but only 10% know it. NKF is a lifeline for all people affected by kidney disease—the largest public health issue you'll ever hear about. Each kidney is attached to a ureter, a tube that carries excreted urine to the bladder. The kidney participates in the control of the volume of various body fluids, fluid osmolality, acid–base balance, various electrolyte concentrations, and removal of toxins.