Excessive Ephedrine Intake Linked to Kidney Stones

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Excessive Ephedrine Intake Linked to Kidney Stones

Reference: Powell T, Hsu FF Turk J, Hruska K. Ma-huang strikes again: Ephedrine nephrolithiasis. Am J Kidney Dis 1998; 32:153-9.

Summary: A 27 year old white male with a congenitally absent kidney and a history of recurrent kidney stones since childhood was evaluated while asymptomatic. He was found to be taking 4 to 12 tablets of an extract of ma huang (Ephedra sinica) containing 6% ephedrine for a daily intake of 40 to 120 mg ephedrine. Analysis of two stones removed from this patient showed them to contain 95% ephedrine and ephedrine metabolites. Other materials in the stone possibly related to etiology were not clearly ruled out. The lab that analyzed the stones reported that 106 (0.064%) of the 166,466 stones analyzed by them over an 18 month period were ephedrine stones. A questionnaire was answered by 15 of the patients who had these stones, and all but two admitted to intake of ephedrine or pseudoephedrine. Seven of the 15 were taking an amount characterized as abusive, and the remaining 6 took highly variable levels.

A review of the solubility of ephedrine and its metabolites by the authors suggests that ephedrine is highly water soluble while pseudoephedrine is much less so. Urine alkalinity decreases solubility of both. However, these features did not help the authors to establish a stone-inducing dose of ephedrine. Literature reports discussed by the authors of massive overdose of ephedrine or chronic abuse showing high urine levels of ephedrine have not mentioned kidney stones. They conclude that excessive ephedrine intake can cause radiolucent kidney stones and that a thorough history should always include dietary supplement intake.

Natural Product Research Consultants, Inc.

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By E. Yarnell

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