Hydrogen breath test for the diagnosis of lactose intolerance, is the routine sugar load the best one?
OBJECTIVE
To evaluate the prevalence of lactose intolerance (LI) following a load of 12.5 g in patients diagnosed as high-grade malabsorbers using the hydrogen breath test (HBT)-25.


METHODS
Ninety patients showing high-grade malabsorption at HBT-25 were submitted to a second HBT with a lactose load of 12.5 g. Peak hydrogen production, area under the curve of hydrogen excretion and occurrence of symptoms were recorded.


RESULTS
Only 16 patients (17.77%) with positive HBT-25 proved positive at HBT-12.5. Hydrogen production was lower as compared to HBT-25 (peak value 21.55 parts per million (ppm) +/- 29.54 SD vs 99.43 ppm +/- 40.01 SD; P < 0.001). Symptoms were present in only 13 patients. The absence of symptoms during the high-dose test has a high negative predictive value (0.84) for a negative low-dose test. The presence of symptoms during the first test was not useful for predicting a positive low-dose test (positive predictive value 0.06-0.31).


CONCLUSIONS
Most patients with a positive HBT-25 normally absorb a lower dose of lactose and a strict lactose restriction on the basis of a "standard" HBT is, in most instances, unnecessary. Thus, the 25 g lactose tolerance test should probably be substituted by the 12.5 g test in the diagnosis of LI, and in providing dietary guidelines to patients with suspected lactose malabsorption/intolerance.
Argnani
Fiorenza
F
Gastroenterologia A e Scienza dell'Alimentazione, Sapienza Università di Roma, Roma 00161, Italy.
Di Camillo
Mauro
M
Marinaro
Vanessa
V
Foglietta
Tiziana
T
Avallone
Veronica
V
Cannella
Carlo
C
Vernia
Piero
P
D000284:Administration, Oral; D001944:Breath Tests; D006801:Humans; D006859:Hydrogen / Q000378:metabolism*; D007785:Lactose / Q000008:administration & dosage / Q000493:pharmacokinetics; D007787:Lactose Intolerance / Q000175:diagnosis* / Q000378:metabolism; D007789:Lactose Tolerance Test; D011237:Predictive Value of Tests
D006859:Hydrogen; D007785:Lactose