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.
This median household has seen its income decline to $51,939 in 2013 from a record high of $56,800 (after adjusting for inflation). As of 2013, anyone earning between $40,187 and $65,501 is in the middle 20% of households. Anyone earning between $20,900 and $105,910 is in the middle 60% of households. One popular rule of thumb holds that anyone earning 25% more or 25% less than the median is within the middle class. By that metric, households earning between $38,954 and $64,924 are middle-class.