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.
If you want to test a cell and take some action if the cell is blank (empty), you can use the IF function. In the example shown column D contains a date indicating when a task was completed. In column E, a formula checks for blank cells in column D. If a cell is blank, the result is a status of Open. If the cell contains a value (a date in this case, but it could be any value) the formula assigns status of Closed. The formula in cell E5 is: