Endocrine Abstracts

Background: Adrenal venous sampling (AVS) is the gold standard method that evaluates the source of aldosterone overproduction in primary aldosteronism. During AVS aldosterone and cortisol are simultaneously measured in order to assess successful adrenal cannulation and lateralization of aldosterone overproduction. However, in patients with both adrenal cortisol and aldosterone overproduction, plasma metaneprhines and normetanephrines can be measured to overcome selectivity and lateralization problems, due to endogenous hypercortisolemia.

Aim: Measurement of metanephrine and normetanephrines during AVS to estimate correct adrenal veins catheterization and lateralization in a patient with both adrenal cortisol and aldosterone overproduction.

Case report: A 60-year-old female with bilateral adrenal adenomas of 3.7 and 4.7 cm presented with hypokalaemia and hypertension. Hormonal work-up showed autonomous aldosterone (aldosterone post-saline infusion test 1910 pmol/l) and cortisol secretion (cortisol post-dexamethasone suppression test 309 nmol/l). AVS without ACTH-stimulation was performed in order to establish the source of both aldosterone and cortisol overproduction, with concomitant measurements of cortisol, aldosterone, plasma metanephrines and normetanephrines from both adrenal veins and inferior vena cava. A metanephrine selectivity index (SI) of ≥12 was used to determine successful catheterization¹. A lateralization index (LI) of ≥2.0 [the ratio of the dominant over the nondominant aldosterone/cortisol (A/F) or aldosterone/metanephrine (A/M)] was used to confirmed lateralization of aldosterone excess². The metanephrine-derived SI in right and left adrenal veins were 29 and 12.40, respectively, confirming the correct cannulation. When cortisol was used for lateralization, A/F ratio was similar on both sides and periphery (0.014 right vs 0.014 left vs 0.01 periphery). In contrast, with metanephrine as the denominator (A/M), aldosterone production lateralized to the left adrenal vein (4.28 right vs 11.85 left), with a ratio of 2.8. The same results occurred when plasma normetanephrines were used to calculate LI (ratio≥2.0). Furthermore, the cortisol/metanephrine (F/M) ratio was more than twice in left adrenal vein compared to the right ratio (843.3 vs 293.2), suggesting a left adrenal source of hypercortisolism.

Conclusions: Plasma metanephrines and normetanphrines on AVS are alternative useful markers for the diagnosis and subsequent treatment decision of a patient with bilateral adrenal adenomas overproducing aldosterone and cortisol.

References

1. Dekkers, Tanja, et al. Hypertension 2013, 62:1152–1157.

2. Rossi, Gian Paolo, et al. Hypertension 2014, 63: 151–160.