Disaccharidase activities in children

Disaccharidase activity in infants and comparison based on symptoms and histological changes

OBJECTIVES

There is uncertainty regarding disaccharidase activity (DA) in infants. In this study, values for DA in infants were established and compared with symptoms and intestinal mucosal histological appearance.

PATIENTS AND METHODS

Disaccharidase activity and histological appearance of endoscopically obtained intestinal mucosal biopsy specimens from 131 infants (75 males; mean age 180 days; range 20-364 days) obtained during an 8-year period were reviewed. Patients were divided into 2 groups on the basis of absence (group 1; n = 56) or presence (group 2; n = 75) of failure to thrive (FTT) and/or diarrhea. These groups were subdivided into 3 subgroups on the basis of histological findings: normal histological appearance (A), mild histological abnormalities (B), and moderate to severe histological abnormalities (C).

RESULTS

The DA from patients in group 1A represent values in infants who were free of diarrhea/FTT and who had normal intestinal mucosal histological appearance. The geometric means (95% CI) in units of DA were as follows: lactase 33.7 (normal range 29.0-39.1), sucrase 48.9 (normal range 44.2-54.1), maltase 160.5 (normal range 144.4-178.3), and palatinase 11.2 (normal range 9.7-12.9). Differences in DA were not related to symptoms, in the absence of histological abnormalities (1A vs 2A), but rather on the presence of histological abnormalities even in the absence of symptoms (1A vs 1B). Differences were also found when patients with FTT and/or diarrhea with abnormal histological appearance (2B and 2C) were compared with patients with no FTT and/or diarrhea with a normal brush border (1A).

CONCLUSIONS

We outline DA values in a large cohort of infants. DA in infants, as in children, relates to intestinal mucosal histological appearance rather than to symptoms.

Ethnic differences in intestinal disaccharidase values in children in Finland

BACKGROUND

Intestinal disaccharidase activities tend to be low in villous atrophy, but there are only a few reports of enzyme activities in children with normal villous architecture.

METHODS

In the current study the data were reviewed on disaccharidase activities in duodenal biopsy specimens of normal villous structure in 223 children undergoing upper gastrointestinal endoscopy in 1997 and 1998. The ancestry was Finnish in 188 children (median age 8.0 years; range, 0.2-18 years), African in 27 children (median age 5.0 years; range, 1-13 years), and other in eight children.

RESULTS

The mean activities of lactase, sucrase, and maltase were significantly higher in Finnish children than in children of African origin (P < 0.0001, P < 0.002, and P < 0.02, respectively). Lactase activity decreased with increasing age (P < 0.001), but age had no significant effect on maltase and sucrase activities. Among Finnish children, 31% (59/188) had lactase activity below the established reference range of 20 units (units are micromoles of substrate hydrolyzed per minute at 37 degrees C per gram of protein) and one child had a probable sucrase-isomaltase deficiency. When these 60 children with low enzyme activities were excluded, the geometric means were lactase, 35.7 units (95% confidence interval [CI], 32.8-38.6 units); maltase, 241 units (95% CI, 225-258 units); and sucrase, 57.5 units (95% CI, 53.5-61.6 units). Among the children of African origin, lactase activity was decreased in 67% (18/27). All three enzyme activities were decreased in parallel more often among the African children (8/27) than among the Finnish children (9/188; P < 0.002).

CONCLUSIONS

Ethnicity has a strong effect on disaccharidase values in children with normal villous structure. African children have lower activities of lactase, sucrase, and maltase in duodenal specimens than do children of Finnish origin.