 when you have a low thyroid. I know that sounds paradoxical, but it's what's called a reflex test. It's high when your thyroid is low, and it's low when you suffer from hyperthyroidism or Graves' disease or when you're getting too much thyroid medication. So it sounds like they're really trying to, really loading you with thyroid medication to compensate for other types of metabolic slowdown, and your TSH is zero.