title: Low lactase activity in a small-bowel biopsy specimen: should dietary lactose intake be restricted in children with small intestinal mucosal damage?
abstract: OBJECTIVE
  Small intestinal mucosal damage can result in decreased lactase activity (LA). When LA is low in a small-bowel biopsy (SBB) specimen, a reduction of dietary lactose intake is usually advised. This is often done by reducing dietary dairy products, which also reduces the intake of calcium, protein and vitamins. Since intestinal damage can have a patchy character and LA varies along the horizontal axis of the small intestine, the relevance of SBB measurement for intestinal LA could be questioned. We compared LA in the SBB with the in vivo capacity to digest lactose using the Lactose Digestion Index (LDI).
  
  
  METHODS
  LA was measured in 18 children aged 0.8-10.9 years (mean 3.9, SD 2.4) undergoing SBB for various indications. In all children the LDI was determined using the (13)C-lactose/(2)H-glucose test.
  
  
  RESULTS
  In 9/18 biopsy specimens LA was low (<10 U/g protein). LDI was normal in 14/18 patients. In 8 out of 9 patients with normal lactase activity, LDI was also normal, while in 6 out of 9 patients LDI was normal despite low LA in the biopsy. In patients with normal LDI, histology was normal in 6/14, in 4/14 mild histological changes (Marsh II) were seen and in 4 patients histological damage was severe (grade III).
  
  
  CONCLUSIONS
  In children with small-bowel mucosal damage, lactose digestive capacity can remain high despite low LA and histological changes in an SBB. Extrapolation of LA in SBB specimens to overall lactose digestive capacity may not be reliable. The advice concerning the restriction of intake of dairy products cannot be based on the data of the SBB only.
authors.affiliation: Beatrix Children's Hospital, University Medical Center Groningen, Groningen, The Netherlands. h.a.koetse@umcg.azg.nl
authors.forename: Harma A
authors.initials: HA
authors.lastname: Koetse
authors.forename: Roel J
authors.initials: RJ
authors.lastname: Vonk
authors.forename: Gieneke B C
authors.initials: GB
authors.lastname: Gonera-De Jong
authors.forename: Marion G
authors.initials: MG
authors.lastname: Priebe
authors.forename: Jean-M
authors.initials: JM
authors.lastname: Antoine
authors.forename: Frans
authors.initials: F
authors.lastname: Stellaard
authors.forename: Pieter J J
authors.initials: PJ
authors.lastname: Sauer
mesh_terms: D001706:Biopsy; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007413:Intestinal Mucosa / Q000201:enzymology* / Q000473:pathology*; D007421:Intestine, Small / Q000201:enzymology* / Q000473:pathology*; D043322:Lactase / Q000378:metabolism*; D007785:Lactose / Q000008:administration & dosage*; D007787:Lactose Intolerance / Q000175:diagnosis; D007789:Lactose Tolerance Test; D008297:Male
chemical_list: D043322:Lactase; D007785:Lactose