Knudsen Christopher D, Di Palma Jack A
From the Division of Gastroenterology, University of South Alabama College of Medicine, Mobile, Alabama 36693, USA.
South Med J. 2012 May;105(5):251-3. doi: 10.1097/SMJ.0b013e318252d428.
Breath tests that measure hydrogen (H2) have been judged reliable for the detection of lactose maldigestion (LM) and fructose malabsorption (FM). Recently, methane (CH4) testing has been advocated and measurement of CH4 in addition to H2 has been shown to increase the diagnostic accuracy for LM.
This study was designed to consider the additional yield from CH4 measurement in patients tested for LM and FM.
Patients reported for testing after an overnight fast, not smoking and with their prior evening meal carbohydrate restricted. After challenge with 50 g lactose or 25 g fructose in water, end-alveolar breath samples collected over a 4-hour duration were analyzed for H2 and CH4. Diagnostic positivity was compared using a cutoff level of 20 ppm increase above fasting baseline for H2 alone, which is consistent with consensus guidelines, versus H2 plus twice CH4, which recognizes that CH4 consumes twice the hydrogen.
There were 406 LM performed in 93 men and 313 women. Of those tested, 124 (30%) had a positive test for H2 and 139 (34%) had a positive test for H2 + CH4 ×2. There were 178 FM tests performed in 31 men and 147 women. Of those tested, 17 (9%) had a positive test for H2 and 42 (23%) had a positive test for H2 + CH4 ×2.
If H2 alone was measured without additional CH4 analysis, 4% of patients with LM and 14% patients with FM would not have been identified.
测量氢气（H2）的呼气试验已被判定对检测乳糖消化不良（LM）和果糖吸收不良（FM）可靠。最近，甲烷（CH4）检测受到提倡，并且已表明除H2外测量CH4可提高LM的诊断准确性。
本研究旨在探讨在进行LM和FM检测的患者中测量CH4的额外收益。
患者在禁食过夜、不吸烟且前一晚晚餐碳水化合物受限后前来检测。在口服50克乳糖或25克果糖后，收集4小时内的终末肺泡呼气样本分析H2和CH4。使用仅H2高于空腹基线增加20 ppm的临界值（这与共识指南一致）与H2加两倍CH4的临界值比较诊断阳性率，后者认识到CH4消耗的氢气量是前者的两倍。
对93名男性和313名女性进行了406次LM检测。在这些检测者中，124人（30%）H2检测呈阳性，139人（34%）H2 + CH4×2检测呈阳性。对31名男性和147名女性进行了178次FM检测。在这些检测者中，17人（9%）H2检测呈阳性，42人（23%）H2 + CH4×2检测呈阳性。
如果仅测量H2而不进行额外的CH4分析，4%的LM患者和14%的FM患者将无法被识别。
