Periodic paralysis caused by abuse of thyroid hormone

Periodic paralysis developed in three patients while they were taking thyroid pills to lose weight. Two of them were taking quite large amounts (1 0 to 30 gr of thyroid extract per day), but one, a man of Japanese ancestry, took the equivalent of only 2 to 4 gr of thyroid extract daily and had no signs of thyrotoxicosis. During a clinical trial he had no attacks of paralysis for 10 months while off thyroid medication, but twice became paralyzed after taking the equivalent of 4 gr of thyroid extract daily for four or five weeks. We suggest that such patients have the same defect that is responsible for periodic paralysis in endogenous thyrotoxicosis, a trait that is most common in Oriental males.