Plasma Metanephrine for Assessing the Selectivity of Adrenal Venous Sampling

Abstract

A drenal hypertension caused by primary aldosteronism comprises the most common curable form of secondary hypertension. In the analytic workup of patients with primary aldosteronism, adrenal venous sampling (AVS) is recommended for establishing the origins of excess production of hormones.1 AVS is a technically demanding procedure in which correct cannulation of the adrenal veins, especially the right, can pose significant difficulty. 2,3 Correct positioning of the catheter is verified by measurement of plasma cortisol concentrations. High cortisol concentrations in adrenal blood compared with peripheral blood ascertain correct catheter placement and thus selective sampling. Because cortisol has a long circulating halflife (100 minutes), increases in adrenal vein (AV) blood above levels of peripheral venous (PV) blood are relatively minor and subsequently subject to interpretative error. Furthermore, as a result of physiological corticotropin fluctuations, cortisol is secreted in a variable fashion so that fluctuating levels can interfere with the interpretation of AVS selectivity. [4][5][6] This problem can be overcome using cosyntropin stimulation. 7 Cosyntropin stimulation, however, adds to the complexity of the procedure and for this reason is not always used.With the above considerations in mind, there seems a need for more reliable parameters than cortisol in assessing the correct positioning of catheters during AVS.8 Plasma metanephrine, the O-methylated metabolite of epinephrine, represents one such alternative analyte. More than 90% of plasma metanephrine is produced within the adrenal medulla, with <10% produced from epinephrine after release from the adrenals. 7 Compared with cortisol, plasma metanephrine has a short circulating half-life of 3 to 6 minutes, resulting in close to 90-fold increases of AV compared with PV concentrations in situations where catheters are correctly positioned.7 Such large Abstract-Adrenal vein sampling is used to establish the origins of excess production of adrenal hormones in primary aldosteronism. Correct catheter positioning is confirmed using adrenal vein measurements of cortisol, but this parameter is not always reliable. Plasma metanephrine represents an alternative parameter. The objective of our study was to determine the use of plasma metanephrine concentrations to establish correct catheter positioning during adrenal vein sampling with and without cosyntropin stimulation. We included 52 cosyntropin-stimulated and 34 nonstimulated sequential procedures. Plasma cortisol and metanephrine concentrations were measured in adrenal and peripheral venous samples. Success rates of sampling, using an adrenal to peripheral cortisol selectivity index of 3.0, were compared with success rates of metanephrine using a selectivity index determined by receiver operating characteristic curve analysis. Among procedures assessed as selective using cortisol, the adrenal to peripheral vein ratio of metanephrine was 6-fold higher than that of cortisol (94.0 versus 15.5; P<0.0001). Ther...

Is there a role for segmental adrenal venous sampling and adrenal sparing surgery in patients with primary aldosteronism?

“…In previous studies including ours (24,25,26,27), some PA patients were found to present autonomous adrenal cortisol overproduction. It has been also proposed that in PA associated with autonomous adrenal cortisol overproduction, plasma metanephrine measured in samples from the adrenal veins would provide a good alternative to cortisol measurement for calculating SI and LI (28).…”

d-Dimer Levels are Significantly Increased in Blood Taken From Varicose Veins Compared With Antecubital Blood From the Same Patient

“…By the time a venous sample is withdrawn from the antecubital fossa, any measurable constituent may have been diluted or filtered by prior passage through 2 or more capillary beds, including the lungs, forearm, and hand. An obvious example of different venous beds having different plasma levels comes from the localization of endocrine tumors, where increased levels of insulin, 25 cortisol, 26 and renin 27 may be relied upon through selective venous sampling. In female patients with saphenous reflux and pelvic vein incompetence, estradiol levels from varicose vein blood are significantly higher than those in patients with saphenous reflux alone.…”

Measurements of plasma metanephrines by immunoassay vs liquid chromatography with tandem mass spectrometry for diagnosis of pheochromocytoma

“…As blood samples were collected with heparin, we validated use of heparinized plasma for the EIA using paired samples of both EDTA and heparinized plasma. Sixteen pairs of heparinized and EDTA anticoagulated samples derived from adrenal venous sampling studies were analyzed (16). Values obtained from measurements in heparinized and EDTA plasma were closely correlated for both NMN (r 2 Z0.975, P!0.001) and MN (r 2 Z0.916, P!0.001) and showed negligible bias ( Supplementary Fig.…”