Endocrine Abstracts

Introduction: We present a case of primary aldosteronism (PA) with adrenal mass, where lateralization of aldosterone production by adrenal-vein sampling (AVS) was discordant with cross-sectional imaging. We highlight an approach to investigation of PA using functional nuclear imaging, and show that subclinical cortisol excess may impact the reliability of AVS.

Case: 70 year old female with 2.6 cm left-sided adrenal mass, with previously normal biochemical work-up. She subsequently developed hypertension, and was re-investigated. She had an elevated ARR of >327 (< 60 pmol/mIU), 24-h urine cortisol of 64.3 (< 229.9 nmol/day), and ACTH of 7.5 (2.0-11.5 pmol/l) with undetectable DHEAS (0.3-6.0 umol/l). AVS was pursued, which lateralized to the right. Lateralization by AVS is the ratio of adrenal vein aldosterone concentrations normalized by respective cortisol concentrations. Thus, cortisol co-secretion from an adrenal mass could make AVS point to the wrong adrenal. On the basis of the interpretation rule previously suggested to detect subtle tumoural cortisol production[1], cortisol co-secretion was suspected to explain the unexpected lateralization results. Dexamethasone-suppressed NP59-iodocholesterol adrenal scintigraphy showed uptake into the left adrenal, with no activity within the right adrenal. The patient consequently underwent left adrenalectomy. Pathology showed an adrenal cortical adenoma with zona glomerulosa hyperplasia. Post-operatively, the patient had a complete clinical and biochemical response by PASO criteria and her ACTH increased compared to pre-operative levels at 14.6 pmol/l.

Conclusions: Though currently the ‘gold-standard’ for detecting unilateral PA, and critical in the work-up for possible adrenalectomy, lateralization of aldosterone excess by AVS is susceptible to pathologic cortisol production asymmetry. We hypothesize that subtle cortisol excess may explain a proportion of cases with AVS-imaging discordance, and propose that functional imaging can help localize autonomous adrenal hormone production, and guide surgical decision making.

References: Kline, G., et al. Clinical Endocrinology (2022), 96(2), 123-131.