Before the advancement of modern medicine, renal failure was often referred to as uremic poisoning. Uremia was the term used to describe the contamination of the blood with urine. Starting around 1847, this term was used to describe reduced urine output, that was thought to be caused by the urine mixing with the blood instead of being voided through the urethra.[citation needed] The term uremia is now used to loosely describe the illness accompanying kidney failure