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

Abstract

METHODS:Twenty healthy volunteers (10 female, 10 male) underwent the 13 C-MBT after intake of 75 mg 13 C-methacetin p.o. on three occasions. Short-and medium-term reproducibility was assessed with paired examinations taken at an interval of 2 and 18 d (medians), respectively. RESULTS:The reproducibility of the 1-h cumulative 13 C recovery (AUC0-60), characterized by a coefficient of variation of 10%, appeared to be considerably better than the reproducibility of the maximum momentary 13 C recovery or the time of reaching it. Remarkably, as opposed to the short gap between consecutive examinations, the capacity of the liver to handle 13 C-methacetin increased slightly but statistically significantly when a repeat dose was administered after two to three weeks.Regarding the AUC0-60, the magnitude of this fixed bias amounted to 7.5%. Neither the time gap between the repeat examinations nor the gender of the subjects affected the 13 C-MBT reproducibility. CONCLUSION:13 C-MBT is most reproducibly quantified by the cumulative 13 C recovery, but the exactitude thereof may be modestly affected by persistent stimulation of CYP1A2 on repeat examinations.

Phase-1 Evaluation of 13C-Liver Function Breath Tests

“…Detailed analyses of the reproducibility data referred in this correspondence have been published elsewhere [10, 11]. In summary, we would like to recall some important observations.…”

“…In our laboratory we pursued prospective evaluation of the reproducibility of the 13 C-methacetin breath test ( 13 C-Meth-BT) [10], the 13 C-alpha-ketoisokaproic acid breath test ( 13 C-KICA-BT) [11], and the 13 C-phenylalanine breath test ( 13 C-PhenAla-BT) [12]. Thus, insight on the precision of the representatives of three main groups of the 13 C-LFBTs has been obtained, since the 13 C-Meth-BT evaluates the microsomal liver metabolism, whereas the 13 C-KICA-BT and the 13 C-PhenAla-BT are dedicated to assess the mitochondrial and the cytosolic metabolic efficiency of the liver, respectively.…”

“…In summary, we would like to recall some important observations. First, in the case of 13 C-Meth-BT it was found that on repeat examinations the exactitude of AUC may be modestly affected by a persistent stimulation of CYP1A2 responsible for a fixed bias which amounted to 8 % [10]. Second, achievement of a necessary reproducibility level of the 13 C-KICA-BT requires calculation of the AUC for a time span from within the range between 0 and 90 min or even better, for 0–120 min [11].…”

Получение (¹³C-метокси)метацетина для изотопных дыхательных тестов

“…Äëÿ ïðîâåäåíèÿ òåñòà ïàöèåíò äîëaeåí âûïèòü ðàñòâîð 75 ìã I â 200 ìë íåñëàäêîãî ôðóêòîâîãî ÷àÿ, à ÷åðåç íåêîòîðîå âðåìÿ äûõàòåëüíóþ ïðîáó àíàëèçèðóþò ñ ïîìîùüþ ñïåöèàëèçèðîâàííûõ ìàññ-ñïåêòðîìåòðîâ, òàêèõ êàê BreathMAT (Ãåðìàíèÿ), HeliView (Êîðåÿ), IsoÐrime è ABCA (Âåëèêîáðèòàíèÿ) èëè ÈÊ-àíàëèçàòîðîâ, íàïðèìåð, IRIS (Øâåöèÿ), FANci2 (Ãåðìàíèÿ), UBiT IR-300 (ßïîíèÿ) [1 -4]. Òåñò ïðèìåíÿþò äëÿ äèàãíîñòèêè ìåòàáîëè÷åñêîé ôóíêöèè ïå÷åíè íà ðàçíûõ ñòàäèÿõ öèððîçà, ãåïàòèòà è äðóãèõ çàáîëåâàíèé [5,6]. Âûâîäû î ñîñòîÿíèè ïå÷åíè äåëàþò íà îñíîâå ñðàâíåíèÿ ôàðìàêîêèíåòè÷åñêèõ çàâèñèìîñòåé ñîäåðaeàíèÿ 13 ëè÷èòü ò.í.…”

¹³C-methacetin breath test in the evaluation of disease severity in patients with liver cirrhosis

“…To improve the diagnostic efficacy of these tests, several quantitative approaches have been proposed to measure metabolic liver function. Currently, breath tests using carbon isotope 13 C are preferentially used 4,5 . The 13 C is biologically identical to 12 C, it is non-toxic and non-radioactive.…”