Your kidneys are complex organs. They regulate the amount of water lost from the body and get rid of waste products, especially urea. Urea is made when any excess amino acids are broken down in your liver.
Middle Class Income for a Family. The annual average income for a middle class family of four is approximately $70, 354. This is based on a 2006 report by the U.S. Census for a family of four. This figure is in the middle of the range of incomes for this section of the population. The median income during this time for all households was $48,561.
According to these class models the lower middle class is located roughly between the 52nd and 84th percentile of society. In terms of personal income distribution in 2005, that would mean gross annual personal incomes from about $32,500 to $60,000.