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.
Several possible ways have been proposed to define the middle class based on median income: Middle Quintile. One particularly narrow definition limits the middle class to households in the middle quintile for income â that is, those who make more than the poorest 40% of Americans and less than the richest 40%. That definition would put the income range for the middle class between $41,187 and $68,212. Middle Three Quintiles.