As reviewed elsewhere (8), numerous studies have confirmed the higher diagnostic sensitivity and advantages of plasma free metanephrines over other tests for detection of PPGLs.
With improved analytical sensitivity of modern LC-ECD and LC-MS/MS instruments, it has become possible to measure urine free metanephrines (16, 24), which also provide improved diagnosis of PPGLs compared to catecholamines and VMA (25).
As yet, however, it is not established whether urine free metanephrines are superior to commonly used urine deconjugated metanephrines for diagnosis of PPGLs.
As outlined in the Endocrine Society Guidelines on PPGLs (8), immunoassays are not recommended as a first choice for measurements of plasma free metanephrines.
Plasma free and urinary fractionated metanephrines are regarded as the first-line tests in screening for PPGL.
for plasma metanephrines below 4X above the upper reference limit), and an additional test is needed to confirm or rule out the presence of PPGL before anylocalization is initiated.
Karel Pacak: Anatomic imaging studies, either CT or MRI, are used for the initial attempts to locate a PPGL.
Maher: Our standard screening modality to detect PPGL in individuals at increased genetic risk is MRI scanning.
Because PPGLs do not always secrete catecholamines, measurements of these analytes in plasma and urine often fail to reveal the presence of the tumors (19).
In the present analysis we used a data set from a large population of patients with hereditary PPGLs, linked to a tumor tissue bank, to examine whether the 5 main hereditary forms of PPGLs might be distinguished by differences in plasma concentrations of the O-methylated metabolites.
The study involved retrospective analysis of data from 173 patients with hereditary PPGLs.
Mutations were confirmed by genetic testing in all patients with MEN 2, VHL syndrome, and hereditary PPGLs due to mutations of SDHD and SDHB genes.