Acute valproate-associated microvesicular steatosis: could the [13C]methionine breath test be useful to assess liver mitochondrial function?

Microvesicular steatosis is a potentially severe manifestation of valproic acid hepatotoxicity due to an acquired impairment of mitochondrial function. Tests currently used to investigate mitochondrial fonction are cumbersome and cannot be used routinely. We report on a noninvasive breath test using [13C]methionine for estimation of mitochondrial function in a case of pure severe valproic acid overdose-induced microvesicular changes. The initially abnormal breath test improved together with the recovery of liver failure. In conclusion, this observation suggests that the [13C]methionine breath test may provide a noninvasive estimate of hepatic mitochondrial function in vivo.