Why is there such a divide in the hypothyroidism doctor world about synthroid (thyroxine) vs armour. it seems docs have very strong opinions either way?

It's silly but true: Hi. It's true that levothyroxine (Synthroid, others) is pure and has less lot-to-lot variability than desiccated porcine thyroid extract (Armour), but they both work. If the patient has a strong preference for Armour, I give them that. If Armour was all we had, we'd all be prescribing that, like back when all we had were animal insulins. I think it's disingenuous to build up any big difference.