Gender affects 13C-ketoisocaproic acid breath test

BACKGROUND AND AIMS: 13C-Ketoisocaproic Acid Breath Test (13C-Kica-BT) has been proposed to assess mitochondrial function. Aim of this study is to evaluate whether gender affects mithocondrial oxidation by means of 13C-Kica-BT in healthy subjects in basal conditions and after an acute oxidative stress induced by ethanol. METHODOLOGY: 50 healthy volunteers were given 1 mg/kg of 13C-Kica together with 20 mg/kg of L-leucine dissolved in 200 ml of orange juice. Breath samples were taken at baseline, every 5 minutes for 45 minutes and then every 15 minutes until 2 hours. Forty-eight hours later the test was repeated 30 min after ethanol ingestion (0.5 g/kg body weight). 13CO2 enrichment in breath was analyzed by isotope ratio/mass spectrometry. Statistical analysis was performed using the student's t test. RESULTS: At baseline conditions, the percentage of Ketoisocaproic acid in 2 hours was significantly higher in females than in males. Ethanol significantly reduces the oxidation of Ketoisocaproic acid. Conversely, no differences were observed between groups after the ethanol oral load. CONCLUSIONS: Decarboxylation of 13C-Kica was significantly higher in females than in males. Ethanol decreases Kica decarboxylation in particular in women. Further studies remain needed to establish whether sexual hormones could interfere with the metabolism of Kica.