LAUSR

INTRODUCTION M itochondrial disorders are rare diseases that are caused by mutations of either mitochondrial DNA or nuclear mitochondrial genes. The clinical manifestations of mitochondrial disorders can vary widely and there is typically a lack of genotypephenotype correlation, which can make diagnosing the disease a challenge. Lactic acidosis can be the main manifestation in many patients with mitochondrial disorder, especially when combined with recurrent episodes of hypokalemia. Lactic acidosis may not always be present and may manifest itself only under physiological stress. Therefore, a high index of suspicion is required when evaluating such patients. Hypokalemia is another feature that can be seen in association with lactic acidosis due to intracellular shift of potassium, but this association is typically underrecognized. Here, we report a patient with longstanding history of recurrent episodes of hypokalemia and lactic acidosis who was diagnosed as having distal renal tubular acidosis (RTA) elsewhere, but was eventually found to have a mitochondrial gene mutation accounting for her clinical presentation.