Background: Adrenal vein sampling (AVS) is the gold standard to identify surgically curable causes of primary aldosteronism. AVS is recognised as technically challenging, with reported success rates of 42-98%1 depending on local expertise. We have 2 new radiologists performing AVS. A semiquantitative point-of-care (POC) cortisol assay was recently reported which increased successful cannulation from 63% to 93%, even in inexperienced hands2.
Aims: Review effectiveness of the POC cortisol assay for successful cannulation
Methods: AVS was performed using ACTH stimulation protocol (50ug/hr continuous cosyntropin). Approximate thresholds were established for each POC cortisol batch (courtesy of Trust Medical, Japan) using stored serum samples. Cortisol levels of 480 nmol/L, 830nmol/L, and 1060 nmol/L resulted in a clear, faint, and absent band respectively. POC assays were evaluated during AVS on 6 consecutive patients between January-May 2018. For this initial phase the intraprocedural decision was made by radiologists using standard radiological criteria.
Successful cannulation was defined biochemically as adrenal/paired peripheral cortisol levels (Selectivity index= SI ) ≥ 3.0
Assessment of cannulation success using the POC assay was evaluated on site and retrospectively by 3 independent reviewers blinded to the lab results.
Results: Mean cortisol levels were 14375.1nmol/l (right adrenal); 605.9nmol/l (paired right peripheral); 12048.3nmol/l (Left adrenal vein) and 526.0nmol/l (paired left peripheral).
In all 6 cases, the radiologist assessed both adrenal veins as successfully cannulated. 4 were successfully cannulated bilaterally using biochemical criteria of SI > 3.0, one borderline (SI 2.7) and one clear failure (SI 1.1). The POC cortisol assay consistently and correctly identified cannulation failure, and in one case, further exploration resulting in successful cannulation. The assay range limited confirmation of cannulation where cortisol levels > 500nmol/l, so may be more useful in protocols without ACTH stimulation.
POC cortisol assays may assist in improving AVS cannulation success, even in less experienced hands.