Urinary 5-HIAA for Diagnosis of Acute Appendicitis in Children, Does it Help?
Urinary 5-HIAA for Diagnosis of Acute Appendicitis in Children, Does it Help?
it is randomized control study. two groups of children (n=191) were divided into two groups A
 and B. Group A included children subjected to the classical protocol of diagnosis of acute
 appendicitis. this protocol consisted of pediatric appendicitis score evaluation, pelvi
 abdominal ultrasound and measurement of serum CRP. Group B, children had the same previous
 assessment plus measurement of urinary 5-HIAA.
1.1- Study design: Patients were randomly categorized into two groups A and B. Randomization
 was achieved using closed envelop method.

 Group A (n= 95) included patients that were evaluated using our institutional protocol. This
 protocol consists of assessment of children using PAS, ultrasound of abdomen and pelvis and
 serum levels of C-reactive protein.

 Group B (n= 96) included children that were evaluated by our institutional protocol. In
 addition, all children gave a mid- stream urine sample for spot urinary 5-HIAA detection.
 Detailed history was taken. This mainly was to exclude cases with history of foods or drugs
 that may affect level of serotonin in urine such as mono amino oxidase inhibitors.

 All related clinical data and laboratory investigations were recorded. 1.2- Quantitation of
 urinary 5-HIAA level: From each participant, a random urine sample was obtained to assess the
 urinary 5-HIAA level using a solid phase competitive enzyme-linked immunosorbent assay
 (ELISA) technique. The commercial kit was purchased and provided by LDN, DN Labor Diagnosika
 Nord GmbH & Co. Nordhorn, Germany; Catalog #: BA E-1900. As stated by the manufacturer, the
 urine samples were methylated to derivatize the 5-HIAA. On the provided microtitre plate, the
 methylated standards, controls and samples are added. 5-HIAA antiserum was then added and
 incubated for 1 hour. After equilibration, excess free antigen and antigen-antibody complexes
 are washed out. The affixed bounded antibodies to the solid phase were detected by an
 anti-rabbit IgG-peroxidase conjugate using TMB as a substrate. The reaction is measured on a
 microplate reader (Tecan Spectra II, Switzerland), at 450 nm. Quantification of unknown
 sample concentration is processed by drawing a standard curve with known standard
 concentrations. The results of 5-HIAA were divided by urinary creatinine and expressed as
 mg/g creatinine. The inter-assay and intra-assay coefficient of variation were 10.8% and 8.6%
 respectively.

 1.3- Clinical outcome: Diagnosis of acute appendicitis was confirmed by histopathological
 examination of resected appendix. According to operative findings and pathological reports,
 the condition ranged from negative appendix to different types of acute appendicitis
 (catarrhal, suppurative, perforated or gangrenous).

 Children did not full filling the requirements for diagnosis as acute appendicitis were
 discharged on symptomatic treatment or after referral to pediatric emergency department.

 Readmitted cases were recorded. 1.4- Statistical analysis: Statistical analysis was done
 using IBM SPSS V. 24 (IBM, NY, USA). A descriptive analysis was obtained for patients
 included in the study. Shapiro-Wilk test was conducted to check for normal distribution of
 dependent variables, such as urinary 5-HIAA, CRP and histopathological findings. X2 test was
 used to compare the categorical data. Student T-test was used to compare the normally
 distributed variable between two groups. Mann-Whitney U test and Kruskal-Wallis test were
 used for comparing the non-normally distributed variables of two and more than two groups,
 respectively. Binary logistic regression was performed to determine the independent
 predictors for acute appendicitis and to combine 5-HIAA and PAS results in both groups.
 Pearson correlation was used for correlating the urinary 5-HIAA with other acute appendicitis
 predictors. Receiver operating characteristic (ROC) curve was constructed to assess the
 diagnostic efficacy of acute appendicitis predictors. The optimal cutoff value for each
 predictor was assessed via the Youden index. The value of AUC ranged from 0.5 to 1.0. The
 ability of a diagnostic test to identify patients with appendicitis was considered optimal as
 AUC value reached closer to 1.0. P-value <0.05 was considered significant
Inclusion Criteria:

 -  all children with suspected acute appendicitis

 Exclusion Criteria:

 -  children received drugs that may affect normal values of urinary 5-HIAA as mono mono
 oxidase inhibitors