My daughter is salt-wasting and since birth has always taken her florinef in two doses. The amount has changed over the years but she now take 1/2 in the morning and 1/2 at bedtime. I believe that her endo feels that this is necessary because of the amount of salt that she loses through the release of fluids during the day. If she were only given it in the morning, by evening she could have complications. This way she is regulated more evenly throughout the day. For 2 1/2 yrs now, her blood pressure has been excellent.