THE RELATIONSHIP BETWEEN LACTOSE TOLERANCE-TEST RESULTS AND SYMPTOMS OF LACTOSE-INTOLERANCE

Objective: A standard for the assessment of lactose malabsorption does not exist, As measured by lactose tolerance tests, insufficient incre ase in blood glucose or increased breath hydrogen (H-2) excretion afte r lactose ingestion is regarded as pathological. In this study, we hav e tried to elucidate the relationship between lactose tolerance test r esults and symptoms after a lactose challenge. This relationship might be an indicator for the validity of the test. Methods: In a prospecti ve study, 309 consecutive patients with suspected lactose malabsorptio n underwent a lactose tolerance test. After consumption of 50 g of lac tose, blood glucose and breath H-2 concentrations were measured. Durin g the test (240 min), the severity of bloating, flatulence, abdominal distention, and diarrhea were semiquantitatively scored as 0, 1, or 2, The individual sum of these four scores was calculated and denoted as the total symptom score (TSS). All subjects were classified according to their TSS to compare symptoms with peak breath-H-2 concentration a nd change in blood glucose concentration, respectively. Results: The g lucose and breath H-2 response were pathological in 51.1 and 39.5% of cases, respectively. A stepwise increase in TSS of 1 point was associa ted with a significant increase (p < 0.05) in mean peak H-2 concentrat ion. However, a significantly lower glucose increment compared with pa tients with a TSS of 0 was found only in patients with a TSS of 2 or 4 . The mean symptom score differed significantly between the positive a nd negative breath tests (p < 0.001), but did not differ between the p ositive and negative glucose response results. Conclusions: This study shows that GI symptoms after a lactose challenge are strongly associa ted with the amount of H-2 excretion. The relationship between the inc rease in glucose concentration and symptoms after a lactose load is le ss evident. Thus, the H-2 breath test seems to be superior to the meas urement of blood glucose increment as a diagnostic tool in lactose mal absorption, although the true predictive value of this test only can b e determined after a period of dietary treatment.