Hyperthyroidism and Hypokalemia

Q: How does hyperthyroidism produce hypokalemic periodic paralysis?

A:

The mechanism by which hyperthyroidism can produce hypokalemic periodic paralysis is not well understood. Thyroid hormone increases Na-K-ATPase activity (thereby tending to drive potassium into cells), and thyrotoxic patients with periodic paralysis have higher sodium pump activity than those without paralytic episodes [23] . Excess thyroid hormone may therefore predispose to paralytic episodes by increasing the susceptibility to the hypokalemic action of epinephrine or insulin [22] . It is also possible that Asians who are susceptible to thyrotoxic periodic paralysis have a mutated calcium channel which, in the euthyroid state, is not sufficient to produce symptoms [20] .