Diagnostic difficulties associated with phaeochromocytoma--4 case illustrations

Area of Science:

• Biochemistry
• Endocrinology
• Oncology

Background:

• Phaeochromocytoma diagnosis is often delayed due to non-specific symptoms and limitations of existing tests.
• The 24-hour urinary vanillyl mandelic acid (VMA) test, historically used in Singapore, exhibits variable sensitivity for phaeochromocytoma detection.
• High performance liquid chromatography (HPLC) assays for urinary catecholamines and metanephrines were introduced in 1993.

Observation:

• This study reports on 4 phaeochromocytoma cases diagnosed since 1993 at Singapore General Hospital.
• Clinical presentations of these patients were diverse, highlighting diagnostic challenges.
• Urinary catecholamine and metabolite levels were compared between phaeochromocytoma patients and controls.

Findings:

• The traditional urinary VMA test showed 100% sensitivity but only 31% specificity for phaeochromocytoma.
• A urinary total metanephrine level of ≥9,000 nmol/day demonstrated both 100% sensitivity and 100% specificity.
• HPLC measurement of urinary total metanephrines offers superior diagnostic accuracy compared to urinary VMA.

Implications:

• The adoption of HPLC for urinary metanephrine measurement significantly enhances phaeochromocytoma diagnosis in Singapore.
• Improved diagnostic accuracy can lead to earlier treatment and better patient outcomes.
• This biochemical marker provides a reliable tool for identifying phaeochromocytoma, reducing diagnostic delays.