Subcutaneous microdialysis in mitochondrial cytopathy

We present the results of subcutaneous microdialysis, a new minimally invas ive biochemical monitoring technique, in mitochondrial cytopathy. We studie d 6 ambulatory patients with mitochondrial cytopathy and 6 controls without mitochondrial disease using a subcutaneous probe for continuous microdialy sis, and obtained measurements of lactate, pyruvate, and glucose from sampl es gathered at 30-60 min intervals during the day and at 3-h intervals at n ight, The lactate:pyruvate ratio (LPR) was calculated and related to diseas e severity and metabolic stress. Microdialysis was well tolerated. Controls had stable lactate and pyruvate values in the normal range and a low LPR ( average values between 0.0114 and 0.0145). Patients had widely fluctuating lactate and pyruvate values, a higher average LPR between 0.0187 and 0.0724 , and marked diurnal variation, especially in the severely affected patient s, Increases in the LPR coincided with metabolic stress in individual cases , We conclude that subcutaneous microdialysis is well tolerated and enables continuous metabolic monitoring of patients with mitochondrial cytopathy. It has particular potential for use in the identification of metabolic risk factors and may help to assess the impact of therapeutic regimens. (C) 200 1 John Wiley & Sons, Inc.