When you have kidney disease, your kidneys are no longer able to remove waste effectively from your body or to balance your fluids. The build up of wastes can change the chemistry of your body causing some symptoms that you can feel, and others that you don't.
Reference to a range of cells is typically of the form (A1:A6), which specifies all the cells in the range A1 through to A6. A formula such as =SUM(A1:A6) would add all the cells specified and put the result in the cell containing the formula itself.
=A1. =A1 is a normal, or relative, cell reference function. When =A1 is entered into cell B2, it refers to the value of data one cell up and one cell left from the cell it is in. Therefore the value displayed in cell C2 will be the value of data in cell B1. Copied to cell R19, the formula will display the data in cell Q18.