loisba:

Synthetic thyroid (Levothroid, Synthroid, etc.) have synthetic T4. Desiccated thyroid is real thyroid from animals and contains both T4 and T3. Most people with Hashimoto's thyroiditis have difficulty converting T4 into T3, thus need supplements of both. Cytomel is the only synthetic T3 that I know of.

I was on synthetic T4 for eight years, and I still went downhill because I didn't know I had Hashimoto's. Once I got on desiccated, the improvement was amazing!

QueenMary50:

You might also hear that desiccated robs calcium from your bones, which is untrue, unless you are on an EXTREMELY high dosage, which is dangerous in lots of ways.

I haven't had a problem with the variations in dosage, since the body naturally doesn't produce a steady, even stream of thyroid anyway. I lost 30 lbs. the first year on desiccated, which I had gradually gained over the eight years on synthetic.

Does your doctor go by Free T4 and Free T3 levels when testing you, does s/he rely on TSH levels, or are levels adjusted according to how you are feeling?