Primary aldosteronism (PA) co-exists with autonomous cortisol production in 5-27% of patients. Adrenal vein sampling (AVS) is the current gold-standard for accurately differentiating between unilateral and bilateral adrenal aldosterone excess. Adrenal vein (AV) cortisol is typically measured to normalise the aldosterone concentration relative to the catheter position in the AV. Therefore, in patients with concurrent autonomous cortisol secretion, there is the potential to mis-interpret cannulation success and lateralisation outcomes. This would ultimately misinform management decisions.
Our objective was to understand the utility of plasma metanephrine and normetanephrine concentrations in the assessment of cannulation success and lateralisation in comparison with cortisol in patients with PA and concurrent abnormal dexamethasone suppression undergoing AVS.
In this retrospective case series, ten consecutive patients with PA and an abnormal 1mg overnight dexamethasone suppression test had plasma metanephrine and normetanephrine measured in addition to aldosterone and cortisol concentrations during AVS. Cannulation success and lateralisation were calculated based on these hormones. Patients underwent either surgery or medical management and were followed-up longitudinally using biochemical and clinical markers of aldosterone and cortisol excess.
AV cannulation success as determined by metanephrine was higher than that determined by cortisol (right AV 100% compared to 80%; left AV 88.9% compared to 85% respectively). Aldosterone lateralisation as determined by either the aldosterone-to-cortisol or aldosterone-to-metanephrine (or normetanephrine) ratio was concordant in seven of ten patients. Based on post-operative outcomes in five patients, metanephrine and normetanephrine are comparable, and in one case superior, to cortisol for the assessment of lateralisation.
In conclusion, metanephrine and normetanephrine assessment during AVS may aid clinical decision making in patients with PA and abnormal dexamethasone suppression.