Briceton has had elevated LFT's on several occasions and at first was just put on Actigall. He later had an ultrasound and CFRLD was diagnosed. From my understanding after talking to the director of my son's GI clinic, and director of the liver clinic, you need to have two "positive" tests to be diagnosed with liver disease-in most cases. For instance: high liver enzymes and a positive ultrasound, or high liver enzymes and a positive liver biopsy, and so forth. In most cases, a liver biopsy is always a last resort and often times not performed unless extremely necessary due to its invasiveness.
In most cases if a patient's LFT's are elevated on two occasions, further investigations is necessary.....and in your child's case, by ultrasound. I would definitely stay on top of your child's LFT's from this point forward and question them each time, but even though his LFT's are elevated a negative ultrasound is wonderful news! Still though, stay on top of it!
Also, CFRLD affects a relatively low amount of CFers, I believe its 3%, but due to the longer life span of CFers (which is a great thing of course!) CFRLD is being diagnosed more often---again another reason to stay on top of it!
Again, this is my understanding and someone else may be able to add more! Have they mentioned Actigall for your son?
Best wishes!