The patient points out that 70,000 people a year need a kidney transplant, but only 10,000 people die each year. House then answers that 60,000 more people should die, but that's nonsense since (virtually) every dying person will have two kidneys to offer, and each patient will be happy with one transplanted kidney. This leaves a current shortfall of 50,000 kidneys meaning only 25,000 more people would have to die, not 60,000.