Diagnosis

A diagnosis of phaeochromocytoma can be confirmed from:

• biochemical confirmation
  • 24 hour urinary free catecholamines, VMA's
  • high performance liquid chromatography for catecholamines - in plasma/urine
  • radioimmunoassay (RIA) for urinary/plasma metanephrines
    
    
    
    • in adrenal incidentalomas
      • 24-hour urinary fractionated metanephrines and catecholamines (1,2)
      • fractionated catecholamines in the 24-hour urinary specimen linked to dopamine-secreting neoplasms
      • when normal diagnosis can be excluded
    • phaeochromocytoma
      • plasma normetanephrine
        • the best single parameter- highest sensitivity and specificity (1)
        • test of choice for the diagnosis or exclusion
      • serum VMA and serum creatinine levels elevated
      • serum CgA significantly higher
        • chromogranin- A (CgA) is secreted by chromaffin cells (3)
          
          
• tumor localization
  • MRI
  • computerized tomography (CT) of the abdomen
    • detect lesions as small as 0.5 inches
    • imaging phenotype - shows characteristics of an adrenal mass on imaging (1)
      • increased attenuation on CT
      • prominent vascularity
      • delayed washout of contrast medium
        
        
• confirmation
  • increased uptake of a radiolabelled catecholamine precursor in the site of the tumour
  • meta-iodobenzyl guanidine (MIBG, I-131 or 123) scintigraphy has been used to identify metastases, recurrent tumors and tumors in rare sites such as the pericardium and urinary bladder
  • MIBG is an adrenergic tissue localizing agent resembling norepinephrine
    
    
• MRI and MIBG scintigraphy are more sensitive than CT

Older investigations/tests that may be used in the diagnostic workup:

• clonidine suppression test
• pentolinium suppression test
• adrenal angiography

Reference:

1. Unger N et al.Diagnostic value of various biochemical parameters for the diagnosis of pheochromocytoma in patients with adrenal mass. Eur J Endocrinol. 2006 Mar;154(3):409-17.
2. Young MF. The Incidentally Discovered Adrenal Mass Young WF Jr N Engl J Med 2007; 356:601.
3. Giovanella L et al. Diagnostic value of serum chromogranin-A combined with MIBG scintigraphy in patients with adrenal incidentalomas. Q J Nucl Med Mol Imaging. 2007 Jun 1.