I would run a complete hormone panel. This is on the very low side of things, and significantly reduces energy, and you may find a tendency to get chilled easily as well. Remember that your thyroid, which not directly in the path for most IMRT patients, does get some scatter radiation and damage. Also your pituitary which is the master and commander of all your other hormone glands. I found that even my testosterone was in the dump, and you know how far away from the field of radiation those jewels are. It's a function of pituitary exposure. So I am on synthroid (took several months of blood work to get the levels right) and testosterone patches daily as well. It has really improved my energy levels.