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.
You can find people earning 7 figures who think they are middle class - by income definition (and a generous one at that), household making between $30,000 and $100,000 are middle class. The top 5% are household incomes of $165,000 and up.