[Analysis of lactase activities of small intestine mucous membrane by double labeled stable isotope technique in subjects with lactase deficiency].

OBJECTIVE

Low lactase activity in small intestine mucosa is the main reason for the occurrence of lactose malabsorption (LM) and lactose intolerance (LI). It would be the basis for the research on LM and LI to find an accurate method to analyze the activity of lactase.

METHODS

In this study, 43 volunteers were selected and divided into LM and LI group according to the results of H2 breath test and symptoms record. Twenty-five grams of 13C-lactose and 0.5 g 2H-glucose in 250ml solution were consumed by all the volunteers. The concentration of total plasma glucose, 13C- glucose and 2H-glucose were measured, the ratio of [13C-glucose]/[2H-glucose] and lactose digestion index (LDI)were calculated which could reflect the lactase activities in the mucous membrane of small intestine.

RESULTS

It was found that there was no significant difference in the concentration of total glucose and 13C-glucose, while the LDI in LM group (0.47 +/- 0.15) was significantly higher than LI group (0.34 +/- 0.14). There was no significant relationship between LDI and 6h cumulative breath H2 amount (r = 0.12, P = 0.46). The 13 C-lactose/2 H-glucose challenged test showed there was still residual lactase activity in small intestine.

CONCLUSION

It was concluded that 13C-lactose/2H-glucosetest can accurately and sensitively determine the lactase activity on small intestinal mucous membrane and digestible lactose amount.