Time Course of H2 Production Following Oral Lactose Load in Children with and without Lactose Intolerance

Sergio Maddaluno1, Marianna Esposito1, Claudio Veropalumbo1, Chiara Gentile1, Iolanda De Napoli1, Maria Caropreso1, Nicola Sannolo3, Pietro Vajro1, 2, *
1 Dipartimento di Pediatria
2 European Laboratory for the Investigation of Food-Induced Diseases, Università degli Studi di Napoli “Federico II”, Italia
3 Dipartimento di Medicina Sperimentale, Sezione di Medicina del Lavoro, Igiene e Tossicologia Industriale, Seconda Università degli Studi di Napoli, Napoli, Italia

© 2009 Maddaluno et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Dipartimento di Pediatria, Università degli Studi di Napoli “Federico II”, Via S. Pansini 5-80131, Napoli, Italy; Tel: +390817462677/4224; Fax: +390817462375; E-mail:



To evaluate whether orocoecal transit time (OCTT) might improve the correct allocation (lactose absorbers vs malabsorbers) of subjects with “borderline” H2 Breath test (H2BT) values ranging 10-20 ppm, and to determine among malabsorbers if OCTT can aid to discern lactose intolerant from tolerant individuals.

Patients and Methods:

OCTT and increment of H2 levels in breath following a dose of lactose were assessed in 49 children (mean age 3.3 years; range 0.6-11.0) suspected of lactose malabsorption. A rise > 20 ppm was used as the criterion to separate malabsorbers from absorbers.


OCTT averaged 177 ± 40 minutes (mean ± SD) in 14 H2 producing lactose absorbers and 78 ± 39 minutes in 22 lactose malabsorbers (p< 0.0001). Among lactose malabsorbers, OCTT was more accelerated in intolerant vs tolerant subjects (42 ± 16 vs 131 ± 23 minutes, p< 0.0001). No lactose intolerant subject had an OCTT > 75 minutes and no lactose tolerant subject had an OCTT < 75 minutes (sensitivity and specificity 100%; PPV and NPV 100%).

Values between 105 and 175 minutes represented a gray area including both absorbers (21%) and all tolerant malabsorbers (100%). OCTT longer than 175 minutes excluded lactose malabsorption (sensitivity 100%; specificity 69%; PPV 84%; NPV 100%). In 6 out of 8 cases with borderline H2BT results, OCTT clear cut values were useful to reach the correct diagnostic allocation.


OCTT evaluation in addition to considering only H2 concentration is a methodological improvement of H2BT procedure. Although it does not represent an absolute gold standard, OCTT testing may aid in reaching a diagnostic conclusion in some patients where clinical and laboratory features after lactose ingestion remains unclear.

Keywords: Lactose malabsorption, lactose intolerance , H2 breath test (H2BT), orocoecal transit time (OCTT), off criterion.