Too few patients completed the study once enrolled.

It is currently assumed that all patients are lactose intolerant post bone marrow transplantation. This pilot study is to assess what the incidence of lactose intolerance is after bone marrow transplantation in children. This will be done using a lactose breath test.

All pediatric patients over the age of 4 years who are scheduled for a stem cell transplant will be approached to assess whether what the incidence of lactose intolerance is in the post transplant period and how quickly recovery occurs. A baseline lactose and lactulose breath test will be performed followed by repeat lactose breath tests starting 2 weeks after day 0 and repeated every fortnight for 10 weeks. Stool pH and reducing substances will be checked at the time of the breath tests to see if there is any correlation.

Inclusion Criteria:

• All patients planned to undergo a stem cell transplant.

Exclusion Criteria:

• Refusal to participate
• Unable to perform breath tests on request (generally under the age of 4 years.)