A high urinary urobilinogen / serum total bilirubin ratio reported in abdominal pain patients can indicate acute hepatic porphyria

Abstract

Abstract Background: Due to its variable symptoms and nonspecific laboratory test results during routine examinations, acute hepatic porphyria (AHP) has always been a diagnostic dilemma for physicians. Misdiagnoses, missed diagnoses, and inappropriate treatments are very common. Correct diagnosis mainly depends on the detection of a high urinary porphobilinogen (PBG) level, which is not a routine test performed in the clinic and highly relies on the physician’s awareness of AHP. Therefore, identifying a more convenient indicator for use during routine examinations is required to improve the diagnosis of AHP. Results: In the present study, we retrospectively analyzed laboratory examinations in 12 AHPpatients and 100 patients with abdominal pain of other causes as the control groups between 2015 and 2022. Compared with the control groups, AHP patients showed a significantly higher urinary urobilinogen level during the urinalysis (P < 0.05). However, we showed that the higher urobilinogen level was caused by a false-positive result due to a higher level of urine PBG in the AHP patients. Moreover, a remarkable increase in the urinary urobilinogen/serum total bilirubin ratio was observed in AHP patients when compared to the control groups. The area under the ROC curve of this ratio for AHP was 1.000 (95% confidence interval, 1.000–1.000, P < 0.01). A cutoff value of 3.22 for the urinary urobilinogen/serum total bilirubin ratio yielded a sensitivity of 100% and a specificity of 100% to distinguish AHP patients from the controls. Conclusion: A reported high urinary urobilinogen level that was adjusted by the serum total bilirubin level (urinary urobilinogen/serum total bilirubin ratio) could be used as a sensitive and specific screening marker for AHP in patients with abdominal pain.