No influence of antihypertensive agents on plasma free metanephrines.
BACKGROUND
Hypertension can be the predominant sign of pheochromocytoma (PCC) and sympathetic paraganglioma (sPGL) and screening for PCC/sPGL is often performed in patients who are already being treated with antihypertensive agents. There is very little information about the influence of antihypertensive drugs on plasma free metanephrines. The aim of this study was to determine whether commonly prescribed antihypertensive drugs can falsely elevate plasma free metanephrines concentrations measured by LC-MS/MS analysis.


METHODS
In a prospective study we included patients with newly diagnosed hypertension, who started monotherapy with an antihypertensive agent (i.e. β-blocker, thiazide diuretic or angiotensin-converting enzyme (ACE) inhibitor). Plasma free metanephrine (MN) and normetanephrine (NMN) levels were measured before and one month after the start of the medication quantified by LC-MS/MS.


RESULTS
Between 2009 and 2014, 39 patients were included (β-blocker n=13, thiazide diuretic n=14 and ACE inhibitor n=12). In the whole group, the median plasma free MN and NMN concentrations at baseline were 0.19 [0.17-0.26] nmol/L and 0.56 [0.38-0.95] nmol/L. One month after the start of antihypertensive treatment, the median plasma free MN and NMN concentrations were comparable; 0.20 [0-16-0.24] nmol/L and 0.63 [0.39-0.75] nmol/L, respectively (P=0.43 and P=0.39). Separate analysis for each of the three antihypertensive agents examined did not reveal any significant changes in the median plasma free MN and NMN concentrations.


CONCLUSIONS
The measurement of plasma free MN and NMN with LC-MS/MS is not affected by use of β-blockers, diuretics and ACE inhibitors. Withdrawal of these drugs prior to the quantification of plasma metanephrines is therefore not necessary.
Department of Endocrinology (AA31), University of Groningen, University Medical Center Groningen, PO-box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: t.osinga@umcg.nl.
Thamara E
TE
Osinga
Department of Laboratory Medicine (EA61), University of Groningen, University Medical Center Groningen, PO-box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: i.p.kema@umcg.nl.
Ido P
IP
Kema
Department of Endocrinology (AA31), University of Groningen, University Medical Center Groningen, PO-box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: m.n.kerstens@umcg.nl.
Michiel N
MN
Kerstens
Department of Laboratory Medicine (EA61), University of Groningen, University Medical Center Groningen, PO-box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: w.h.a.de.jong@umcg.nl.
Wilhelmina H A
WH
de Jong
Department of Laboratory Medicine (EA61), University of Groningen, University Medical Center Groningen, PO-box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: h.j.r.van.faassen@umcg.nl.
Martijn
M
van Faassen
Department of Endocrinology (AA31), University of Groningen, University Medical Center Groningen, PO-box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: r.p.f.dullaart@umcg.nl.
Robin P F
RP
Dullaart
Department of Endocrinology (AA31), University of Groningen, University Medical Center Groningen, PO-box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: t.p.links@umcg.nl.
Thera P
TP
Links
Department of Endocrinology (AA31), University of Groningen, University Medical Center Groningen, PO-box 30.001, 9700 RB Groningen, The Netherlands. Electronic address: a.n.a.van.der.horst@umcg.nl.
Anouk N A
AN
van der Horst-Schrivers
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000959:Antihypertensive Agents / Q000494:pharmacology*; D016022:Case-Control Studies; D002853:Chromatography, Liquid; D005260:Female; D006801:Humans; D008297:Male; D008676:Metanephrine / Q000097:blood*; D008875:Middle Aged; D053719:Tandem Mass Spectrometry
D000959:Antihypertensive Agents; D008676:Metanephrine
Antihypertensive medication; Metanephrines; Pheochromocytoma; β-blockers