A nutritional assessment is in "Complications in Head and Neck Surgery", pages 42, basically based on Harris-Benedict formula for basal energy expenditure (BEE). Trying to find the hydration formula aspect, if it's in here, but it's 794 pages.

You can also check for dehydration by pulling the skin on the back of your hand and see how quickly it retracts. Some people may just have loose skin, so its not failsafe, as well as taking meds, vitamins that darken the urine, vitamin C, but both can give a quick assessment, in addition to other findings.

Even knowing this, I was dehydrated during treatment, needed several IV infusions. I wasn't talking in half I should have, even with the feeding tube. Guess there is a difference in reading and practicing it.

There are many hydrstion calculators on-line...search Daily Water Intake, that are based on weight or caloric intake. I just did one, and came out to 90 ounces. Of course, there are other factors..climate, activity....