Biochemical diagnosis of pheochromocytoma and paraganglioma: analytical challenges and perspectives for optimization

Pheochromocytomas and paragangliomas (PPGL) are rare but potentially life-threatening neuroendocrine tumors whose diagnosis relies primarily on the biochemical detection of excessive catecholamine production or metabolism. Plasma free metanephrines and urinary fractionated metanephrines remain the cornerstone biomarkers recommended for initial screening. However, their performance is influenced by substantial pre-analytical and analytical variability, requiring strict standardization in sampling conditions and assay methodology. The emergence of liquid chromatography-tandem mass spectrometry (LC-MS/MS) has improved specificity, but inter-laboratory variability and lack of harmonized cut-offs still challenge reproducibility. Chromogranin A (CgA), while broadly used in neuroendocrine tumor monitoring, shows poor diagnostic accuracy for PPGL. Recent advances in molecular profiling, metabolomics, and artificial intelligence (AI) suggest future opportunities for more integrated diagnostic pathways, although these approaches remain investigational in PPGL. This review critically examines the current biochemical tools used in PPGL diagnosis, discusses pitfalls and limitations, and focuses on unresolved analytical vulnerabilities, inter-laboratory variability, and the translational implications of these issues for routine laboratory practice, while also proposing perspectives for optimization, including emerging biomarkers, integrative diagnostics, and harmonization strategies.