Serum 5-hydroxyindoleacetic acid is equivalent to 24-hour urinary 5-hydroxyindoleacetic acid for the diagnosis of carcinoid syndrome

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Introduction: Neuroendocrine tumors (NET) are characterized by their ability to secrete amines and peptides. Overproduction of serotonin results in the carcinoid syndrome (CS), present in approximately 20% of all NET patients. Measuring the main metabolite of serotonin, 5-hydroxyindoleacetic acid (5-HIAA), in 24-hour urine is frequently used for the diagnosis and follow-up of CS patients. However, these measurements are prone to sampling error and may be troublesome for patients. Serum 5-HIAA measurements might be a more reliable and convenient alternative in the diagnosis of CS.

Aim(s): To assess the value of serum 5-HIAA measurements in the diagnosis of CS.

Materials and methods: We retrospectively analyzed all NET patients at our center with a paired serum and 24-hour urine 5-HIAA measurement between 2021 and 2023. The diagnostic performances of serum and 24-hour urine 5-HIAA for the diagnosis of CS were measured by area under the receiver operating characteristics curve (AUROC) analyses. The optimal cutoff value of serum 5-HIAA for the diagnosis of CS was determined by the Youden index.

Conference:

Presenting Author:

Authors: Kerolles M, Mulders M, Mirzaian M, van den Berg S, Feelders R,

Keywords: 5-hiaa, carcinoid syndrome, neuroendocrine tumor, biomarker,