Diagnostic value of measuring serum serotonin and urinary 5-hydroxyindoleacetic acid concentration in the diagnosis of functional dyspepsia

Introduction : The pathogenesis of functional dyspepsia remains largely unknown. The diagnosis is based on subjective symptoms. However, many efforts are being made in searching for the causes and objective indices which could facilitate the diagnosis and explain the variety of clinical symptoms of this disease.
Aim : To evaluate serotonin secretion and metabolism in various clinical forms of functional dyspepsia.
Material and methods : The study comprised 25 clinically healthy persons (K), two groups with an equal number of patients (n = 25) with epigastric pain syndrome (EPS) and postprandial distress syndrome (PDS), aged 19-49 years (mean age 34.6 ±13.4). The diagnosis of functional dyspepsia was based on the Rome III criteria. Patients with H. pylori infection were excluded from the study. The blood sample was drawn in fasting conditions and 24-hour urine collection was performed. Serum serotonin and urinary 5-hydroxyindoleacetic acid (5-HIAA) concentrations were measured by ELISA method and IBL antibodies were applied (catalogue numbers: RE 59121, RE 59131).
Results : Serum serotonin concentration in the controls was 162.9 ±49.1 ng/ml, in patients with EPS – 225.87 ±113.3 ng/ml (p < 0.05) and in patients with PDS – 152.7 ±83.2 ng/ml (p > 0.05). 5-HIAA urinary excretion was respectively in the studied groups: K – 5.65 ±2.31 mg/24 h, EPS – 4.12 ±1.85 mg/24 h (p < 0.01) and PDS – 3.06 ±1.61 mg/24 h (p < 0.01).
Conclusions : In patients with functional dyspepsia serotonin homeostasis is disturbed. Evaluation of 24-hour urinary 5-HIAA excretion can be a useful measurement in the differential diagnosis of the clinical forms of functional dyspepsia and can be helpful in choosing the appropriate treatment.