Incorrect SI units. The CME Quiz Questions (September 15, 2015, p. 441) contained an error in answer choice C for Quiz Question #6 from the article “Potassium Disorders: Hypokalemia and Hyperkalemia” (p. 487). The correct answer choice for Q#6, answer C should have read: “Because serum potassium concentration drops approximately 0.3 mEq per L (0.3 mmol per L) for every reduction of 100 mEq (100 mmol) in total body potassium, the deficit can be estimated in patients with abnormal losses and decreased intake.” The online version of the quiz has been corrected.