Labetalol displayed a small early eluting peak when monitoring the metanephrine
qualifier transition m/z 180 [right arrow] 165 (Fig.
The preoperative diagnosis of pheochromocytoma is supported by elevated levels of urine and blood catecholamines and their metabolites, metanephrine
and vanillyl mandelic acid (VMA).
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 in nonpregnant women, the diagnosis is usually based upon the results of 24-hour urinary fractionated metanephrines
and normetanephrine) and catecholamines (dopamine, norepinephrine, and epinephrine) and plasma fractionated metanephrines
 Nonstandard abbreviations: PMets, plasma metanephrines
; NMN, normetanephrine; MN, metanephrine
; UMets, urine MNs; PCC, pheochromocytoma.
Large paragangliomas with low or normal metanephrine
concentrations have been described in patients with SDHB [succinate dehydrogenase complex, subunit B, iron sulfur (Ip)] mutations, which reflects the typically immature phenotypic features of these tumors.
Plasma free and urinary fractionated metanephrines
are regarded as the first-line tests in screening for PPGL.
Although the total metanephrine
concentration has been used in the past, the current recommendation is for split metanephrines
(MN and NMN) to be reported, because this approach enhances the sensitivity of the test.
Serum norepinephrine, epinephrine, metanephrine
and normetanephrine levels studied for hypertension aetiology were within normal limits.
For lipids, metanephrine
, normetanephrine, or hemoglobin A1c, there were no differences between the groups.
Blood adrenaline, noradrenaline, metanephrine
, normetanephrine and adrenocorticotropic hormone levels were also normal.
(7,10) Furthermore, PGLs with germline mutations in SDHB and SDHD are also typically negative for epinephrine and metanephrine