Abstract：
BACKGROUND: Diagnosing lactose malabsorption is usually based on hydrogen excretion in breath after a lactose challenge. However, a proportion of subjects with lactose malabsorption will not present a rise in hydrogen. Measuring excretion of methane or stable isotope labeled 13CO2 after ingestion of 13C-lactose has been proposed to mitigate this problem.
OBJECTIVE: The aim of the study was to assess the performance of measuring methane and 13CO2 in individuals with normal hydrogen excretion compared to a genetic lactase non-persistence test.
METHODS: Individuals referred for lactose breath testing and healthy controls were included. Participants received 13C-enriched lactose, performed breath testing, and underwent genotyping for a marker of lactase non-persistence (13910C*T). Using genotype as gold standard, the performance of measuring methane and 13CO2 excretion was assessed.
RESULTS: 151 subjects participated in the study, 50 of which presented a lactase non-persistent genotype. Of these, 72% were correctly diagnosed through hydrogen excretion of ≥ 20 ppm above baseline. In subjects with normal hydrogen excretion, cumulative 13C excretion had an area under the curve (AUC) of the receiver operating characteristics (ROC) curve of 0.852. Sensitivity was 93% and specificity was 51% for the current cutoff of 14.5%. The optimal cutoff was 12.65% (sensitivity 93%, specificity 70%). The ROC curve of peak methane had an AUC of 0.542 (sensitivity of 14%, specificity of 91% for cutoff ≥ 10 ppm).
CONCLUSIONS: In individuals with genetically demonstrated lactase non-persistence and negative hydrogen breath test, the use of 13C-lactose with measurement of 13CO2 excretion and hydrogen is a well-performing test to detect the lactose malabsorption and performs better than methane in our cohort.
OBJECTIVE: The aim of the study was to assess the performance of measuring methane and 13CO2 in individuals with normal hydrogen excretion compared to a genetic lactase non-persistence test.
METHODS: Individuals referred for lactose breath testing and healthy controls were included. Participants received 13C-enriched lactose, performed breath testing, and underwent genotyping for a marker of lactase non-persistence (13910C*T). Using genotype as gold standard, the performance of measuring methane and 13CO2 excretion was assessed.
RESULTS: 151 subjects participated in the study, 50 of which presented a lactase non-persistent genotype. Of these, 72% were correctly diagnosed through hydrogen excretion of ≥ 20 ppm above baseline. In subjects with normal hydrogen excretion, cumulative 13C excretion had an area under the curve (AUC) of the receiver operating characteristics (ROC) curve of 0.852. Sensitivity was 93% and specificity was 51% for the current cutoff of 14.5%. The optimal cutoff was 12.65% (sensitivity 93%, specificity 70%). The ROC curve of peak methane had an AUC of 0.542 (sensitivity of 14%, specificity of 91% for cutoff ≥ 10 ppm).
CONCLUSIONS: In individuals with genetically demonstrated lactase non-persistence and negative hydrogen breath test, the use of 13C-lactose with measurement of 13CO2 excretion and hydrogen is a well-performing test to detect the lactose malabsorption and performs better than methane in our cohort.
摘要：
背景：诊断乳糖吸收不良通常基于乳糖激发后呼吸中的氢排泄。然而,一部分乳糖吸收不良的受试者不会出现氢气升高。已经提出了在摄入13C-乳糖后测量甲烷或稳定同位素标记的13CO2的排泄以减轻该问题。
目的：该研究的目的是评估与遗传乳糖酶非持久性测试相比，在氢排泄正常的个体中测量甲烷和13CO2的性能。
方法：纳入了进行乳糖呼气测试的个体和健康对照。参与者接受了富含13C的乳糖，进行呼气测试,并进行了乳糖酶非持久性标记物的基因分型（13910C*T）。使用基因型作为黄金标准，评估了测量甲烷和13CO2排泄的性能。
结果：151名受试者参与了这项研究，其中50种呈现乳糖酶非持续性基因型。其中,72％的人通过比基线高≥20ppm的氢排泄得到正确诊断。在氢排泄正常的受试者中，累积13C排泄的受试者工作特征(ROC)曲线的曲线下面积(AUC)为0.852.对于目前的14.5%的截止值,敏感性为93%,特异性为51%。最佳截止值为12.65%(灵敏度93%，特异性70%)。峰值甲烷的ROC曲线的AUC为0.542（灵敏度为14％，临界值≥10ppm的特异性为91%)。
结论：在遗传证明乳糖酶不持久性和氢呼气试验阴性的个体中，在我们的队列中,使用13C-乳糖并测量13CO2排泄和氢气是检测乳糖吸收不良的一项性能良好的测试,并且其性能优于甲烷.
目的：该研究的目的是评估与遗传乳糖酶非持久性测试相比，在氢排泄正常的个体中测量甲烷和13CO2的性能。
方法：纳入了进行乳糖呼气测试的个体和健康对照。参与者接受了富含13C的乳糖，进行呼气测试,并进行了乳糖酶非持久性标记物的基因分型（13910C*T）。使用基因型作为黄金标准，评估了测量甲烷和13CO2排泄的性能。
结果：151名受试者参与了这项研究，其中50种呈现乳糖酶非持续性基因型。其中,72％的人通过比基线高≥20ppm的氢排泄得到正确诊断。在氢排泄正常的受试者中，累积13C排泄的受试者工作特征(ROC)曲线的曲线下面积(AUC)为0.852.对于目前的14.5%的截止值,敏感性为93%,特异性为51%。最佳截止值为12.65%(灵敏度93%，特异性70%)。峰值甲烷的ROC曲线的AUC为0.542（灵敏度为14％，临界值≥10ppm的特异性为91%)。
结论：在遗传证明乳糖酶不持久性和氢呼气试验阴性的个体中，在我们的队列中,使用13C-乳糖并测量13CO2排泄和氢气是检测乳糖吸收不良的一项性能良好的测试,并且其性能优于甲烷.
