Department of Gastroenterology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.
J Gastroenterol Hepatol. 2013 Sep;28(9):1462-8. doi: 10.1111/jgh.12273.
Lactose malabsorption (LM), diagnosed currently using lactose hydrogen breath and tolerance tests (LHBT, LTT) with a high, nonphysiological dose (50-g), may mimic irritable bowel syndrome (IBS). In LM-endemic areas, clinically significant malabsorption (lactose intolerance) may be better diagnosed using a lesser dose, and positive results so obtained may predict response to milk withdrawal more effectively.
Fifty patients each with IBS (Rome III) were evaluated using LHBT and LTT with 50-g, 25-g, and 12-g lactose. Sensitivity and specificity of LHBT and LTT with different dosages (gold standard: lactase gene C/T-13910 polymorphism) and symptom development were evaluated. Effect of milk withdrawal was studied.
Of 150 patients, 37/50 (74%) and 28/50 (56%) had LM by LHBT and LTT using 50-g lactose; 41/50 (82%) and 31/50 (62%) had LM using 25-g lactose, and 14/50 (28%) and 29/50 (58%) using 12-g lactose, respectively. Sensitivity and specificity of LHBT using 50-g, 25-g, and 12-g lactose were 92.6%, 52.0%, and 94%, 60%, and 36.4%, 88.2%, and those of LTT, 92%, 80.0%, and 84.8%, 82.4%, and 66.7%, 58.8%, respectively. Breath hydrogen correlated with lactose dose. Though patients developing symptoms with 50-g lactose exhaled more hydrogen than those remaining asymptomatic, hydrogen levels did not differ following 25-g and 12-g dosages in relation to symptom development. Patients' milk intake was 335 ± 92 mL/d (≈ 16.7 ± 9.6-g lactose). Positive LHBT using 25-g dose better predicted symptom resolution than by 50-g and 12-g lactose.
Twenty-five gram is the ideal dose of lactose for LHBT and LTT in LM-endemic areas.
目前，乳糖吸收不良（LM）通过使用高剂量（50g）的乳糖氢呼气和耐量试验（LHBT、LTT）进行诊断，可能会模仿肠易激综合征（IBS）。在 LM 流行地区，使用较小剂量可能更能诊断出有临床意义的吸收不良（乳糖不耐受），并且阳性结果可能更有效地预测对停奶的反应。
使用 50g、25g 和 12g 乳糖对 50 例符合罗马 III 标准的 IBS 患者进行 LHBT 和 LTT。评估 LHBT 和 LTT 的不同剂量（金标准：乳糖酶基因 C/T-13910 多态性）的敏感性和特异性以及症状发展，并研究停奶的效果。
在 150 例患者中，50 例患者中 37 例（74%）和 28 例（56%）通过 50g 乳糖的 LHBT 和 LTT 显示 LM；41 例（82%）和 31 例（62%）通过 25g 乳糖的 LHBT 和 LTT 显示 LM，14 例（28%）和 29 例（58%）通过 12g 乳糖的 LHBT 和 LTT 显示 LM。使用 50g、25g 和 12g 乳糖的 LHBT 的敏感性和特异性分别为 92.6%、52.0%和 94%、60%和 36.4%、88.2%和 84.8%；LTT 的敏感性和特异性分别为 92%、80.0%和 84.8%、82.4%和 66.7%、58.8%。呼气氢与乳糖剂量相关。尽管 50g 乳糖组中出现症状的患者呼出的氢气多于无症状患者，但在 25g 和 12g 剂量下，症状发展与氢气水平无差异。患者的牛奶摄入量为 335±92mL/d（≈16.7±9.6-g 乳糖）。25g 剂量的阳性 LHBT 比 50g 和 12g 乳糖更好地预测症状缓解。
在 LM 流行地区，25g 是 LHBT 和 LTT 的理想乳糖剂量。
