(Tribune News Service) -- A nationwide comprehensive recall pulled two brands of thyroid medicine off shelves after FDA testing found their strength lacking. The FDA-posted recall notice written by manufacturer RLC Labs said this “sub potency” is why all 483 lots of all strengths of Nature-Throid and WP Thyroid were recalled.

RLC posted a list of all the recalled lots.

Testing of samples from six lots found “the product may have as low as 87% of the labeled amount of (active ingredients) Liothyronine or Levothyroxine.”

Obviously, this can leave a patient’s hypothyroidism, having an underactive thyroid, untreated.

Walmart, one of the drugs’ retailers, put out a 68-page list of pharmacies that had either Nature-Throid or WP Thyroid.

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Those who suffer a medical problem from this or any other drug should first contact a medical professional. Then, report it to the FDA’s MedWatch Adverse Event Reporting program either via the FDA website or by a form obtained at 800-332-1088.

Anyone with questions about the recall can email recall@rlclabs.com or call RLC at 877-797-7997, Monday through Thursday from 9 a.m. to 6 p.m., and Friday from 9 a.m. to 5 p.m. EDT.