If anyone’s interested, I have collected the FDA recalls of thyroid replacement products for the past four years into one (long) file. Both synthetic and natural products have, indeed, been recalled for problems with potency, labeling of dosage, stability under normal storage conditions, etc. Interestingly, a thyroid uptake test kit was also recalled.
Contact me directly by e-mail if you want a copy. Some of the recalled pills have expiration dates into 1998.