Renal Diseases: Pathology, Diagnosis and Management - Hardcoverby Emma Farlow (Editor) The kidneys are a pair of bean shaped organs located on either side of the spine, which filter blood in the human body. They are responsible for maintaining proper electrolyte levels, eliminating waste and regulating fluid balance in the body. The condition wherein the kidneys cannot filter the blood properly due to an injury is called renal disease or kidney disease. Renal diseases are classified into two categories, namely,