NEW YORK (Reuters Health) – Serial measurement of blood urea nitrogen (BUN) provides the most valuable prognostic information of six routinely collected admission laboratory tests in patients admitted to the hospital with acute pancreatitis, and increases in BUN independently predict mortality, clinicians from Massachusetts report in the July issue of Gastroenterology.

“Tracking of BUN levels during the initial course of acute pancreatitis is a very inexpensive, non-invasive way to monitor disease course and help guide further resuscitation efforts,” Dr. Bechien U. Wu, of the Center for Pancreatic Disease, Brigham and Women’s Hospital, Boston, told Reuters Health.

Dr. Wu and colleagues evaluated the accuracy of serial BUN versus serial hemoglobin (Hgb), two routine laboratory tests that reflect intravascular volume status, for prediction of in-hospital mortality in patients with acute pancreatitis.

Data were derived from 69 US hospitals for the 4-year period January 2003 to December 2006 and included 13,384 acute pancreatitis patients overall and 5819 cases with three or more BUN and Hgb measurements in the first 48 hours.

Data analysis revealed that during the first 48 hours of hospitalization BUN levels were persistently higher among patients who died than among patients who survived (p < 0.0001). No such relationship existed for Hgb. According to the investigators, an elevated admission BUN and an increase in BUN within the first 24 hours of hospitalization were both independently associated with increased mortality. For every 5-mg/dL increase in BUN during the first 24 hours, the age- and gender-adjusted odds ratio for death increased by 2.2, the researchers report. “We found that early changes in blood urea nitrogen were surprisingly accurate for identifying patients at substantially higher risk of in-hospital mortality,” Dr. Wu told Reuters Health. By contrast, a reduction in BUN during the first 24 hours of hospitalization was associated with significantly improved survival. Of six routinely collected admission laboratory tests examined (BUN, calcium, creatinine, WBC count, Hgb, and glucose), serial BUN measurement was “the most valuable” single test for predicting in-hospital mortality, Dr. Wu and colleagues report. Of all six tests, BUN yielded the highest area under the concentration-time curve (AUC) for predicting mortality at admission (AUC = 0.79), 24 hours (AUC = 0.89), and 48 hours (AUC = 0.90). The combination of admission BUN level and change in BUN at 24 hours yielded an AUC of 0.91 for in-hospital mortality, they note. Dr. Wu and colleagues conclude that an elevated admission BUN “should be a signal to physicians to institute more intensive early resuscitation efforts.” Serial measurement of BUN, they say, “provides valuable additional clinical information regarding the efficacy of initial resuscitation as well as potential disease progression.” Reference:
Gastroenterol 2009;137:129-135.