Abstract
Background
Diagnosis of lactose intolerance is based on a “positive” H2 breath test associated with abdominal symptoms. The present study established to
what extent the occurrence of symptoms during a “negative” H2 breath test may result from a “nocebo effect” instead of lack of sensitivity of the
procedure.
Methods
Between 2005 and 2007, 636 outpatients performed a standard 4-h 25 g lactose tolerance test. The test was positive in 254, negative in 325, and 57 patients
were H2 “non-producers”. Twenty-seven patients reporting symptoms despite a negative H2 breath test underwent a “sham” breath test following ingestion of 1 g of glucose. Fifty-four patients presenting with documented lactose intolerance were
used as controls.
Results
Twelve out of 27 patients (44.4%), and unexpectedly also 14 (25.9%) controls presented
abdominal symptoms during the sham test. The difference between the two groups was
not significant (P < 0.15) OR 2.28; C.I. 0.77–6.78.
Conclusion
In most instances, symptoms reported by patients during a negative lactose H2BT cannot be attributed to a false-negative test. Instead, a non-organic component,
resulting from negative expectations (“nocebo effect”) is likely implicated. Moreover,
also in patients diagnosed as lactose intolerant, the need for restricting the primary
source of dietary calcium should be critically reconsidered.
Abbreviations:
H2BT (hydrogen breath test), IBS (irritable bowel syndrome), LM (lactose malabsorption), LI (lactose intolerance), NP (hydrogen non-producers)Keywords
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Article info
Publication history
Published online: March 15, 2010
Accepted:
February 3,
2010
Received:
August 26,
2009
Identification
Copyright
© 2010 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Inc. All rights reserved.
