To make a long story short, I can’t take T4 at all. It turns into reverse T3. Over a period of several months I’ve been taking T3 only (cytomel). When I got to 75 mcg my free T3 was 3.5 (3.1-6.8). The doctor agreed that we could raise it a bit. After several weeks of taking 100 mcg of T3, my free T3 is 3.1. Any idea of why? My GP is referring me to an endocrinologist. On Thursday I am having my B12, vitamin D, iron etc. checked.