Use of corticotropin-induced potassium changes in the diagnosis of both hypo- and hyperkalemic periodic paralysis.

Both hypo- and hyperkalemic periodic paralysis may be difficult to diagnose conclusively when patients are not seen during attacks. Since paralysis of both types can be induced with ACTH, we have determined the frequency of this response in small groups of patients. Weakness or paralysis with appropriate changes in serum K concentration resulted from ACTH gel administration, in 4 of 5 patients with known hypokalemic periodic paralysis and in 3 of 3 patients with hyperkalemic paralysis. No adverse effects of the test were observed, but hospitalization and careful monitoring were necessary. The response to ACTH appears to be a sensitive, useful aid to the diagnosis of both hypo- and hyperkalemic periodic paralysis.