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.
Story Highlights. 1  Middle class is America's favorite socioeconomic group. 2  The median, or middle, household income in the United States today is $50,054. 3  Popular vision of middle class is rooted in 1950s, when a generation found solid jobs, bought houses in the suburbs and took modest family vacations.