Diagnostic Impact of Adrenal Vein Sampling in Adrenal Cushing's Syndrome

Role of adrenal venous sampling in the differential diagnosis and treatment protocol of ACTH-independent Cushing's syndrome with bilateral adrenal lesions

PURPOSE

The diagnosis and management of adrenocorticotropic hormone-independent Cushing's syndrome (AICS) with bilateral adrenal lesions remain challenging. Some studies have explored the value of adrenal vein sampling (AVS) in patients with AICS; however, more investigations are needed to assess its benefits for diagnosis and treatment planning in this population.

METHODS

Thirteen patients with clinical, biochemical and imaging evidence of AICS with bilateral adrenal lesions underwent AVS in our department from 2017-2022 were recruited. Only the data from nine patients for whom AVS succeeded were finally included in this study and further analyzed. Blood samples were successfully collected from both adrenal veins (AV) and inferior vena cava (IVC) in these nine patients, and the levels of plasma total cortisol (PTC) and plasma aldosterone concentrations (PAC) were measured. The ratio of the PAC of the AV to the IVC was calculated, and the PTC to PAC ratios were compared between AV. The surgical strategy was chosen according to the results of AVS. Postoperative histology and immunohistochemistry of the adrenal tissues were performed. The prognosis was evaluated based on the improvement of clinical symptoms and biochemical parameters (including PTC and ACTH measurements).

RESULTS

Patients with AICS were clinically diagnosed based on clinical signs, results of functional tests and the presence of bilateral adrenal lesions as observed on computed tomography imaging. An AV to IVC PAC ratio greater than 2 confirmed successful AVS. The PTC to PAC ratio (high side to low side) was greater than 2 in four patients, and less than 2 in five patients. The postoperative pathological results were consistent with clinical diagnosis and AVS. During the mean follow-up of 33 months, all nine patients achieved varying degrees of clinical improvement.

CONCLUSION

Our study showed that AVS helped to distinguish unilateral and bilateral lesions, identify the laterality of the autonomous hypercortisolism, and improve therapeutic strategy selection in patients with AICS and bilateral adrenal lesions.

Recent Advances in the Clinical Application of Adrenal Vein Sampling

We reviewed clinical research investigating the applications of adrenal vein sampling (AVS). AVS could be applied not only to primary aldosteronism (PA) but also to other endocrine diseases, such as adrenocorticotropic hormone (ACTH) independent Cushing syndrome (AICS) and hyperandrogenemia (HA). However, the AVS protocol requires improvements to increase its success rate. Using the computed tomography image fusion, coaxial guidewire technique, and fast intraprocedural cortisol testing (CCF) technique could improve the success rate of catheterization in AVS for PA. ACTH loading could be considered in medical centers with a low selectivity of AVS for PA but is not essential in those with mature AVS technology. The continuous infusion method should be recommended for ACTH stimulation in AVS for PA to reduce adverse events. AVS has not been routinely recommended before management decisions in AICS, but several studies verified that AVS was useful in finding out the source of excess cortisol, especially for distinguishing unilateral from bilateral disease. However, it is necessary to reassess the results of AVS in AICS with the use of reference hormones to fully normalize cortisol levels. In addition, it is essential to determine the optimal model that combines AVS results and mass size to guide the selection of surgical plans, including identifying the dominant gland and presenting the option of staged adrenalectomy, to minimize the impact of bilateral resection. For HA, AVS combined with ovarian intravenous sampling to locate excess androgens could be considered when imaging results are equivocal.