CF is usually diagnosed by measuring the amount of salt in a persons sweat. CF affects exocrine glands. Sweat glands are one kind of exocrine gland. The altered CF gene changes how the body handles salt. More salt is lost in sweat. The amount of sweat is normal, but the salt in it is high.
Normal mucus in thin and slippery. In the airways, it removes dust and germs. It also lubricates the ducts and passageways of other organs, kind of like oil in a car. In CF, the changes in salt transport cause changes in water transport. The mucus loses some of its water and is thick and sticky. This thick mucus blocks tubes and organ passageways.
Sweat tests are done to diagnose CF and they can only diagnose it; they cannot predict the severity. There is no connection between sweat salt level and the severity of the disease in an individual. So just because Drew has days where he tastes salty and days where he does not doesn't tell us anything other than what we already know - that hes got CF.
We give Drew sodium in his bottles to replenish and compensate for what his body loses. Right now, its liquid that we just add to his already not-so-tasty bottles (its no wonder the kid hates feeding time!) but eventually we will just have to pour table salt on all of his food and he will also be encouraged to drink things like Gatorade which contain a lot of salt (would have been nice to know that Gatorade was loaded with salt BEFORE the feet swelling started during pregnancy!)
So for anyone curious, yes, he tastes salty, but I just noticed it for the first time a this week. And please just take my word for it - don't lick my kid.