Endocrine Abstracts

Objective: (1) To review normative data for catecholamines using our cohort of hyperaldosteronism patients undergoing adrenal vein sampling. This adds to the previously published data of normative values in a cohort of patients with cortisol-producing adenoma. (2) To demonstrate the usefulness of the noradrenaline to adrenaline ratio in the interpretation of adrenal venous sampling results.

Design: 38 patients underwent successful, bilateral adrenal venous cannulation for the investigation of primary hyperaldosteronism.

Method: Catheterisations were carried out by a single interventional radiologist. Intravenous cosyntropin (50 mcg/hr) was started 1 hour before the procedure. Blood samples were collected for catecholamines, cortisol and aldosterone. Results Measured concentrations of adrenaline and noradrenaline were highly variable. Median values in the left adrenal veins were 38.85 nmol/L (range: 4–301.4) and 15.45 nmol/L (2.7–67.8) for adrenaline and noradrenaline respectively with a noradrenaline to adrenaline (NA:Adr) ratio of 0.34 (0.12–3.67). In the right adrenal vein, adrenaline levels were 61.4 nmol/L (7.7–499.8), noradrenaline levels 21.5 nmol/L (5.9–263) with a NA:Adr ratio of 0.3 (0.08–7.26). 4 patients had reversed NA:Adr ratio in one or both adrenal veins.

Conclusion: In agreement with previous studies, there is a large variability in the levels of adrenaline in both adrenal veins. However, the use of NA:Adr appear to be a more consistent tool when assessing normal catecholamine levels in the adrenal veins. A ratio of <1 is seen in over 90% of cases. This may prove helpful in the functional assessment of adrenal lesions. Variations of catecholamine levels and ratios within different subgroups, such as gender and those with co-secreting adenomas will also be discussed. Interestingly the patients with reversal of the NA:Adr ratio bilaterally had proven obstructive sleep apnoea (OSA). Many studies has shown raised urinary catecholamines in patients with OSA but to our knowledge, this is the first association of reversed NA:Adr ratio in patients with OSA.

Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.