The Tyranny of the TSH Let’s talk about further thyroid testing. In an effort to reduce laboratory costs and find ever cheaper methods of evaluating thyroid function, the TSH has become the more commonly accepted first line test with “reflex” follow-up. Now this assumes three very important concepts. The feedback mechanism between the pituitary and the thyroid is intact and functional. It assumes a “normal distribution.” That is, a typical “bell shaped” curve of all values from low to high….