How long have they been taking thyroid pills? One thing that always happens is as the years go by, the dosage needs to keep being increased because the low dosage that they're probably on now aren't as effective.
Most hypothyroid people are also overweight and fat holds a bunch of toxins..And the liver is the main "fat burner" of the body. Kind of hard to burn fat with a congested liver..
Some people claim if you cleanse the body enough, not just by liver flushing, but in general.. You can *fix* your thyroid and it'll start working like it's supposed to.