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Normal Lab Tests Do Not Rule Out Inflammatory Bowel Disease in Children

Additional evaluation should be considered for patients with symptoms and normal screening lab test results.

Normal screening test results in children with recurrent abdominal pain and loose stools might falsely reassure clinicians that inflammatory bowel disease (IBD) is not present. The Pediatric IBD Collaborative Research Group sought to determine how often four tests (hemoglobin level, platelet count, albumin level, and erythrocyte sedimentation rate) are normal in children with newly diagnosed IBD. The researchers obtained clinical, demographic, and laboratory data from a registry of 18 U.S. and Canadian pediatric gastroenterology centers for 526 patients with newly diagnosed IBD (392 with Crohn disease and 134 with ulcerative colitis).

Of the cases that were classified as being mild on presentation, 21% with Crohn disease and 54% with UC had normal results on all four tests, whereas among cases with moderate or severe disease, only 3.8% of those with Crohn disease and 4.3% of those with UC had normal results on all four tests. Overall, 60% of patients had normal albumin levels, 50% had normal platelet counts, 32% had normal hemoglobin levels, and 26% had normal erythrocyte sedimentation rates. Hemoglobin levels were significantly lower in patients aged 6 to 12 years with severe UC than with severe Crohn disease (8.3 vs. 10.7 g/L), whereas in patients aged 6 to 12 years with moderate or severe disease and in all patients aged 12 years, hemoglobin levels did not differ significantly between those with UC and those with Crohn disease. Patients with Crohn disease limited only to the colon were more likely to have normal test results than those with more-extensive disease. In patients with UC, disease severity was directly correlated with the extent of bowel involvement and the number of abnormal tests. The combination of presence of blood in the stool and at least one abnormal lab test was 98% sensitive for the diagnosis of IBD in the study population.

Comment: Delayed diagnosis of IBD can lead to more-active disease, increased morbidity, and complications. Although gastrointestinal bleeding, weight loss, and abdominal tenderness nearly always prompt referral to a pediatric gastroenterologist, suspicion of IBD in a child with a more indolent presentation of chronic abdominal pain or diarrhea should also prompt expeditious referral, regardless of normal laboratory findings.

— Jill M. Baren, MD, MBE, FACEP, FAAP

Published in Journal Watch Emergency Medicine August 3, 2007

Citation(s):

Mack DR et al. Laboratory values for children with newly diagnosed inflammatory bowel disease. Pediatrics 2007 Jun; 119:1113-9.

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