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.
Here's the breakdown of how much you have to earn each year to qualify as middle-income, depending on the size of your family: Household of one: $24,042 to $72,126. Household of two: $34,000 to $102,001. Household of three: $41,641 to $124,925. Household of four: $48,083 to $144,251.