13C-methacetin breath test reproducibility study reveals persistent CYP1A2 stimulation on repeat examinations

Figure 2 Relationship of the reproducibility of the cumulative ¹³C recovery, expressed in terms of the coefficient of variation for paired examinations (CV_p), on the time span taken for the calculation of the area under the curve. The short-term reproducibility (open rectangles) assessment involved performance of 20 pairs of ¹³C-methacetin breath tests separated by a median 2-d break, whereas 20 pairs of examinations accomplished at a median interval of 18 d were considered for the evaluation of the medium-term reproducibility (filled rectangles). AUC: Area under the curve.