The usefulness of methacetin breath test in the initial diagnosis of nonalc oholic fatty liver disease in children with simple obesity - preliminary report

Introduction: 13C-methacetin breath test (MBT) is a noninvasive test in the diagnosis of fatty liver. For the clinical definition of nonalcoholic fatty liver disease (NAFLD) a coexistence of abnormal liver ultrasound with an increase ALT concentration is assumed, but the ""gold standard"" in its diagnosis is still invasive liver biopsy. Aim of the study: Evaluation of MBT in the diagnosis of NAFLD in children with simple obesity. Material i methods: The prospective study involved 26 children aged 6-18 years (median=13.7 years, 95%CI: 12.35- 14.24) diagnosed with simple obesity without previous liver disease. In all children MBT, ultrasonography of the liver and ALT concentration (normal <40 IU/ml) were obtained. Based on the automatical analysis of MBT the patients were divided into 3 groups: 1K - normal results (n=19), 2K - pathologic (n=1) and 3K - uspecified (n=6). In addition, MBT results were analyzed by the researcher. By using two criteria: peak shift of 13CO2 excretion time ≥30th minute and the value of the cumulative dose <90% of the average score in 40th minute test duration, the study population was divided into two groups: 1B - normal results (n=18) and 2B - pathologic (n=8). An analysis of the results indicating the sensitivity, specificity, positive and negative predictive value was performed for each of its interpretation. Statistical analysis was performed in a package Statistica . Results: NAFLD was diagnosed in 4 (15.38%) patients by taking as clinical criteria features of liver steatosis on ultrasound and increased ALT >40 IU/ml. In the automatic analysis of MBT not a single patient met the criteria for NAFLD. Using improved criteria of MBT interpretation adopted by the researcher, the result was abnormal in 8 patients, including 3 that met the clinical criteria for NAFLD. This provided 75% sensitivity, 77% specificity, 37% positive predictive value, 94% negative predictive value of the test. Conclusions: 13C-methacetin breath test may be useful in screening for the exclusion of NAFLD in children with simple obesity. It is necessary to develop new criteria for its interpretation and to conduct the study on a larger populationscale.