The evaluation of the repeatability of the C-ketoisocaproate breath test for assessing hepatic mitochondrial function.

The C-ketoisocaproate (C-KICA) breath test (BT) has been recently proposed as a non-invasive test for assessing hepatic mitochondrial function. Results of the C-KICA BT can be expressed as different parameters. However, the best parameter for expressing the C-KICA BT result is uncertain which hinders use of the BT in routine clinical practice. We have investigated the repeatability of different parameters of C-KICA BT. Thirteen healthy adult subjects (5 men and 8 women) underwent a C-KICA BT on two occasions separated by a gap of approximately 30 days. There were no significant differences between the repeated measurements for all the test parameters over 30 days. Furthermore, the Bland Altman statistics showed no fixed or proportional bias for any of the test parameters. The cumulative C-dose enrichment over 60 min had the lowest within-subject variability of 12% compared to all other test parameters. The cumulative C-dose enrichment over 60 min could be a very useful parameter for the C-KICA BT to detect impaired hepatic mitochondrial function in patients with chronic liver diseases.