Dear patient, Thanks for your health concerns. Adjusting diuretics gradually is part of controlling patients with valvular leaks , however, it should be done in a supervised fashion after consulting with his cardiologist/internist or family physician. It does not seem a dramatic increase from 40 to 80 on a pm dose, but he is 85 years old and diuretics have to be used more carefully in the elderly. The importance of making a joint decision about medication uptitration with your physician is also that diuretics can deplete potasium, calcium, magnesium, etc, and low levels can also give you fatigue and weakness; kidney failure can also make you retain fluid and feel tired, so his physician might want to chekc simple blood tests to make sure this is not the case. Hope this helps, wish you and your dad the best health, Dr Brenes Salazar MD Cardiovascular Diseases Mayo Clinic MN