Typically, when
thyroid levels are high, TSH is low and when
thyroid levels are low, as they are with hypothyroidism, TSH is high... this is what your doctor was looking at. With secondary or central hypothyroidism, this pattern does not hold true, because there's nothing wrong with the thyroid; it simply needs TSH to stimulate it. The problem is in, either the pituitary or hypothalamus gland, so the thyroid is not getting the stimulation it needs to produce the thyroid hormones.