5-Hydroxyindoleacetic acid as a biomarker for revealing perforation in acute appendicitis

The present study investigated the level of 5-hydroxyindoleacetic acid (5-HIAA) in perforated and nonperforated appendicitis patients. This issue is important for timely diagnosis of acute appendicitis complications and making decision about the surgical plan and type of incision.

This prospective study was conducted on patients with acute appendicitis. 5-HIAA levels were measured in urine spot sample of every patient before the surgery. The patients were finally included based on result of pathology for presence of appendicitis or not and sorted by direct surgical detection for exist of perforation or not. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of 5-HIAA were investigated. The data were statistically analyzed by SPSS v.27.

A total of 150 patients were included in two groups as 40 patients in the perforated appendicitis group and 110 patients in the noncomplicated acute appendicitis group. The average age of patients in the perforated appendicitis group was 28.8 ± 6.07 years, and that of patients in the acute appendicitis group was 29.6 ± 6.96 years. 94 patients (63%) were male, and 56 (37%) were female. No significant difference was observed in terms of age or sex between the two groups. The difference in the 5-HIAA concentration between the acute appendicitis group (0.3 ± 0.04 mg/dl) and the perforated appendicitis group (0.5 ± 0.03 mg/dl) was significant (P < 0.001). The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy were 82%, 62%, 75%, 77%, and 88% respectively.

This study shows that the 5-HIAA concentration in patients with perforated appendicitis can potentially increased significantly more than that in patients in the early stages of acute appendicitis. further studies with larger sample sizes are needed to prove the present results.