Blood test pattern can avoid diagnostic delay in IBD

Changes in standard blood tests up to one year before a diagnosis of IBD might be key to identifying the disease earlier.

According to a Queensland study of 838 patients diagnosed with IBD from 1996 to 2014, a laboratory pattern of inflammation and probable iron deficiency was evident in patients with Crohn’s disease 4-12 months before their diagnosis.

The findings suggest a diagnostic delay exists, that if avoided could lead to earlier initiation of treatment and potential modification of the disease trajectory.

The study found each patient had a mean of four blood tests performed in the three years leading up to their diagnosis.

Of note, serum albumin levels dropped significantly 385 days prior to a diagnosis of Crohn’s disease and MCV (mean cell volume) dropped 115 days prior.

A significant rise in the platelet count was reported at 145 days prior to diagnosis.

“In patients with Crohn’s disease, a high platelet count, a low albumin level, and a low MCH (mean corpuscular haemoglobin) were associated with ileal (L1 and L3) disease location and with a stricturing or penetrating (B2 or B3) disease behaviour,” the study authors said.

MCV could be considered a more sensitive marker of iron deficiency than serum ferritin in the setting of pre-diagnosis inflammatory bowel disease, they added.

“While the observed signal of laboratory abnormality was not present in all patients – 1 in 5 CD patients had abnormal testing 12 months prior to diagnosis – laboratory abnormality may be a useful tool to assess likelihood of Crohn’s disease for a significant proportion of patients presenting with abdominal symptoms.”

However there was less advance warning for ulcerative colitis, consistent with the shorter duration of symptoms reported by patients with ulcerative colitis compared to Crohn’s disease.

“For patients with ulcerative colitis, a significant change in albumin level, MCV, haemoglobin level, platelet count and serum iron level was observed at or around diagnosis (p < 0.01, unpaired two-tailed t test).”

The researchers concluded there was certainly scope to use patterns of laboratory test results over time to identify subsequent risk of IBD, especially in those with an affected first degree relative.

“Delay to diagnosis occurs in other chronic inflammatory disorders and is representative of a balance of risk: on the one hand avoiding exposure to toxic therapy in patients with self-limiting inflammation and on the other hand administering disease-modifying therapy before significant progression of disease.”

“This delay may be ameliorated to some extent by promotion and dissemination of diagnostic algorithms to primary practitioners.”

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