DELTA-10 PPM VERSUS DELTA-20 PPM - A REAPPRAISAL OF DIAGNOSTIC-CRITERIA FOR BREATH HYDROGEN TESTING IN CHILDREN

Objective: To reevaluate the timing and level of rise in breath hydrog en (H-2) excretion following oral lactose challenge in children with r espect to the subsequent development of symptoms consistent with lacto se intolerance. Methods: Breath hydrogen test (BHT) data from 581 indi viduals < 19 yr of age (mean age 7.4 yr), all of whom had a fasting ba seline breath Ht concentration of < 20 ppm, were reviewed. All subject s ingested 2 g/kg lactose (maximum 50 g) and had breath H-2 analysis a t 30-min intervals for 3 h. Symptoms of abdominal pain, bloating, gas, and diarrhea were monitored. Results: Seventeen percent of subjects h ad no H-2 detectable in their breath at any time, 41% had a rise <10 p pm from baseline, 6% increased 10-19 ppm, and 36% had a rise greater t han or equal to 20 ppm. Symptom development (gas, bloating, abdominal pain, diarrhea) was similar in the non-Hz excretors, the Delta < 10 pp m, and the Delta 10-19 ppm groups. Compared to the <10 ppm or <20 ppm groups, subjects with a rise of greater than or equal to 20 ppm were m ore likely to develop diarrhea (p < 0.0001), gas (p < 0.0001), bloatin g (p < 0.0001), and abdominal pain (p < 0.0001). Symptoms were more co mmon in the greater than or equal to 20 ppm group than in the Delta 10 -19 ppm group (p < 0.02 for diarrhea, p < 0.0001 for gas, bloating, an d abdominal pain). Fifty-three percent of subjects with a rise in brea th H-2 <20 ppm reported symptoms during or after the BHT, and 9% of th ose with a rise greater than or equal to 20 ppm were asymptomatic. Con clusion: A rise of breath H-2 concentration of greater than or equal t o 20 ppm over baseline appears to correlate better with subsequent sym ptom development than does greater than or equal to 10 ppm. However, t he frequently poor association between symptoms of lactose intolerance and breath H-2 excretion suggest caution in the interpretation of the clinical significance of the BHT.