E-Poster Presentation ESA-SRB-ANZBMS 2021

Apparent primary aldosteronism: a case of mistaken identity (#406)

Jinghang Luo 1 , Emma Boehm 2 , Christopher J Yates 1 2 , Devaang Kevat 1 , Shane Hamblin 1 2 , I-Lynn Lee 1
  1. Endocrinology and Diabetes, Western Health, Melbourne, VIC, Australia
  2. Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia

Introduction

Primary aldosteronism (PA) is suspected clinically based on an elevated aldosterone-renin ratio (ARR). However, aldosterone may be overestimated on immunoassays in chronic kidney disease (CKD). We present a case of a young woman with malignant hypertension and end stage renal failure, who had apparent PA on immunoassay but had low true aldosterone levels on liquid chromatography-tandem mass spectrometry.

Case description

A 19-year-old woman was referred for investigation of apparent PA. She had presented with bilateral retinal haemorrhages, hypertension of 180/90 mmHg and new oligo-anuric renal failure with no medical history, medication use or family history. On examination, she weighed 32kg with a height of 146cm, with a BMI of 15 kg/m2; investigations demonstrated anaemia and secondary hyperparathyroidism, consistent with some chronicity of renal failure. Haemodialysis was initiated, and a renal biopsy showed collapsing focal segmental glomerulosclerosis; evaluation for autoimmune, infective or obstructive causes was negative.

Her ARR was elevated at 332 [<71] using the DiaSorin Liaison XL chemiluminescence immunoassay. A non-dedicated computed tomography scan showed no obvious adrenal pathology. Interestingly, aldosterone decreased despite volume reduction on two sets of pre- and post-dialysis specimens subsequently (see Table 1). After seeking a second opinion, two aldosterone levels of 3 and 2 pmol/L [sitting 0-400, standing 30-800] were measured using liquid chromatography-tandem mass spectrometry; this finally excluded PA as a cause of her presentation.

Discussion

Primary aldosteronism is difficult to diagnose in CKD both clinically and biochemically. The aldosterone-renin ratio is elevated in CKD, but patients may not have spontaneous hypokalaemia. Commercial immunoassays without an extraction step can overestimate aldosterone by up to 50% even in moderate CKD. This is likely due to the accumulation of urinary metabolites such as aldosterone-18-glucoronide and tetrahydroaldosterone-3-glucoronide. Liquid chromatography-tandem mass spectrometry avoids this issue, and should be considered when PA is being considered in CKD.

61161288af587-tab1.PNG