How many kidneys does a human body have?

The kidneys have many functions, including regulating blood pressure, producing red blood cells, activating vitamin D and producing some glucose. Most evidently, however, the kidneys filter body fluids via the bloodstream to regulate and optimize their amount, composition, pH and osmotic pressure. read more

The kidneys also help maintain the proper fluid balance in the body. The kidneys filter all the blood in the body around 12 times an hour, removing excess fluid and waste and manufacturing urine. Occasionally, someone is born with just one kidney or loses a kidney due to disease or injury. read more