Serum 5-Hydroxyindoleacetic Acid Measurements for the Diagnosis and Follow-up of Carcinoid Syndrome
Authors' conclusion
Serum 5-HIAA measurements are equivalent to 24-hour urine 5-HIAA measurements for the diagnosis of CS in patients with NET and form an accessible alternative.
Study context
- Population
- Patients with neuroendocrine tumor (NET) at a tertiary care hospital, 136 (35.9%) with carcinoid syndrome (CS); 153 control samplesplus 153 control samples
- Participants
- 379 patients
- Exposure
- Serum 5-HIAA vs 24-hour urine 5-HIAA for diagnosis of CS
- Outcome
- Diagnostic performance for CS measured by AUROC
Methodological detailssingle-centre (tertiary care hospital), diagnostic accuracy
- Single-centre (tertiary care hospital)
- Diagnostic accuracy
Main finding
As reported in the abstract
AUROC for diagnosis of CS, total NET cohort
| Group | AUC |
|---|---|
| Serum 5-HIAA | 0.824 |
| 24-hour urine 5-HIAA | 0.843 |
AUC
Serum 5-HIAA0.824
24-hour urine 5-HIAA0.843
- Serum 5-HIAA vs 24-hour urine 5-HIAA: P = 0.50 — performance similar
Observational data: associations, not effects.
Further findings
| Outcome | Serum 5-HIAA | 24-hour urine 5-HIAA | P value |
|---|---|---|---|
| AUROC for diagnosis of CS, SSA-naïve subgroup (n = 141) | P = 0.66 | ||
| AUC | 0.915 | 0.938 |
- Optimal serum 5-HIAA cutoff for CS (subgroup of somatostatin analog (SSA)-naive CS patients and controls)
- 139.4 · nmol/L
Correlation of serum with 24-hour urine 5-HIAA and with flushing, diarrhea, carcinoid heart disease
- Correlation serum vs 24-hour urine 5-HIAA, r (P < .001)
- 0.892
- OR for flushing, diarrhea and carcinoid heart disease per 100 nmol/L increase (P < .001)
- 1.047-1.073
Original publication
Serum 5-Hydroxyindoleacetic Acid Measurements for the Diagnosis and Follow-up of Carcinoid Syndrome. J Clin Endocrinol Metab. Published 2 May 2025. doi:10.
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