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Dig Dis Sci. 2014 May;59(5):1012-6. doi: 10.1007/s10620-013-2980-7. Epub 2013 Dec 20.

A diagnostic approach to patients with suspected lactose malabsorption.

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  • 1Laboratory of Gastroenterology, Rabin Medical Center, Beilinson Campus, Petach Tikva, Israel.



The lactose breath test (LBT) is the standard technique for diagnosis of lactose malabsorption. However, it is time-consuming, strenuous for the patient and has been reported to have low sensitivity. The lactose intolerance quick test (LIQT) measures lactase activity in duodenal biopsies and may be performed as part of upper gastrointestinal endoscopy.


The purpose of this study was to assess the role of the LBT and LIQT in the case management of suspected lactose malabsorption.


The study group included 69 consecutive patients evaluated by the LBT followed by the LIQT. The test results were compared, and the sensitivity, specificity, and predictive values of the LBT were calculated.


Mean age of the patients was 54.4 years, male/female ratio was 1:3, and mean body mass index was 25.2. None had celiac disease on duodenal biopsy. The LIQT was positive for hypolactasia in 55 patients (80 %): mild in 14 (25 %) and severe in 41 (75 %); 10 (18 %) were symptomatic during the LBT. The LBT was positive for lactose malabsorption in 32 patients (46 %). Of the 37 patients with normal findings on the LBT, 24 (65 %) had positive findings on the LIQT: 11 (30 %) mild hypolactasia, 13 (35 %) severe hypolactasia. In one case, the LBT was positive and the LIQT was negative. The LBT had a sensitivity of 56 %, specificity 93 %, positive predictive value 97 %, and negative predictive value 35 %.


The LBT may serve as a diagnostic screening tool for lactose malabsorption. Symptomatic patients with negative LBT results should be referred for second-line testing with the LIQT.

[PubMed - indexed for MEDLINE]
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