It is my understanding that a thyroid problem can cause generalized fasciculations. But if a thyroid problem were the cause for fasciculations in an individual then the diagnosis should not be BFS. BFS is diagnosed after other routine explanations are ruled out; and the thyroid is ruled out (or in) with a blood test.
Not 100% sure on any of the above; it's just my understanding.
It is worth having a blood test, but don't be alarmed if it comes back normal. I have had electrolytes, calcium, B12, thryroid hormone, parathyroiod hormone, glucose and muscle enzyme tests and they all came back normal. Some were checked again after a few months had passed and they were still normal.
