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.
The Urban Institute defined the middle class as adults with size-adjusted household incomes of between $30,000 and $100,000 for families of three. The Pew Research Center defines the middle-income category as including adults with family-of-three equivalent incomes between two-thirds and double the national median.