Can intestinal free fat bonding protein (I-FABP) be a marker in the diagnosis of acute abdomen?

Aim: Patients with acute abdominal pain are a group frequently encountered in the emergency department. Differential diagnosis is usually of vital importance. Their easy availability and wide use makes biochemical markers highly important in the early diagnosis of acute abdominal pain. This study was planned to investigate the diagnostic value of intestinal type FABP (I-FABP) in acute abdomen patients.Materials and Methods: This prospective, descriptive study was performed at the Karadeniz Technical University Medical Faculty Emergency Medicine Department with patients applying with acute abdominal pain in 2008-2009. One hundred seventy-one patients with acute abdominal pain aged 18 and above and with no history of trauma were enrolled, together with a control group of 130 healthy individuals. Patients undergoing surgery during hospitalization were classified according to surgical findings, while non-operated patients were classified on the basis of diagnosis reached by mutual agreement between the emergency physician and general surgery physician. Contact (by telephone, patient visit, invitation to check-up) was made with non-admitted and discharged patients 1 week after application. Patients were divided into subgroups with the aim of comparing biochemical parameters analyzed on the basis of definitive diagnosis. Serum I-FABP, D-dimer and blood leukocyte levels of patients applying with acute abdominal pain, measured at time of admission, were compared with those of healthy individuals.Results: When the definitive diagnoses of the patients in the study as a result of FM, laboratory tests, imaging and surgery were analyzed, the largest group consisted of 51 (29.8%) non-specific patients, followed by 30 (17.5%) with gall bladder diseases and 17 (9.9%) ileus-volvulus patients. Mean I-FABP level of the 171 patients enrolled was 170.1±543.4 pg/ml, compared to a mean I-FABP level of 61.4±47.4 pg/ml in the healthy volunteer controls. Although I-FABP levels were higher in the patient group, the difference was not statistically significant (p>0.05). Of the causes of acute abdominal pain, only I-FABP levels measured at application among patients with acute mesenteric ischemia and intra-abdominal mass (708.6±669.1 and 387.4±1380.2, respectively) were higher than those in healthy individuals (p<0.05). Sensitivity of 71.4%, specificity of 94.6%, PPV of 41.7 and NPV of 98.4 were determined for the optimal cut-off value of 144.9 pg/ml obtained for diagnosis of mesenteric ischemia. Sensitivity of 60.0%, specificity of 83.8%, PPV of 30.0 and NPV of 94.8 were determined of the optimal cut-off value of 14.7 pg/ml determined for diagnosis of intra-abdominal mass. Mean I-FABP level for the 40 operated patients was 173.5±343.06 pg/ml compared to an I-FABP level of 168.6±606.7 pg/ml for non-operated patients. This difference was not statistically significant (p>0.05). When the correlations between these guide parameters in acute abdominal pain were examined a very weak but significant correlation was determined between D-dimer and leukocyte number (r=0.262, p=0.001) and D-dimer and I-FABP (r=0.168, p=0.02).Conclusion: With its high specificity and NPV, serum I-FABP level may be a useful biochemical parameter for excluding mesenteric ischemia in patients regarded as acute abdomen. We determined that I-FABP levels measured on application cannot be used as a marker in deciding on the need for surgery. The results of our study now need to be examined by better planned and wider research with larger patient numbers.Key words: I-FABP, acute abdomen, D-dimer, mesenteric ischemia, abdominal mass