Oral Presentation ESA-SRB-AOTA 2019

Variation in the aldosterone/renin ratio indicates the need for age- and sex-specific reference ranges when screening for primary aldosteronism (#243)

Pravik Solanki 1 2 , Stella Gwini 3 4 , Peter J Fuller 2 5 , Jimmy Shen 2 5 , James CG Doery 1 6 , Kay Weng Choy 6 , Jun Yang 1 2 5
  1. Department of Medicine, Monash University, Clayton, VIC, Australia
  2. Endocrinology, Monash Health, Clayton, Victoria, Australia
  3. Department of Epidemiology and Preventive Medicine, Monash University, Clayton, Victoria, Australia
  4. University Hospital Geelong, Barwon Health, Geelong, Victoria, Australia
  5. Endocrine Hypertension Group, Hudson Institute of Medical Research, Clayton, VIC, Australia
  6. Pathology, Monash Health, Clayton, Victoria, Australia

Background: The aldosterone/renin ratio (ARR) is the standard screening test for primary aldosteronism (PA), a treatable disease causing ~10 – 20% of hypertension. Current guidelines define ARR>70 (pmol/L)/(mIU/L) as positive regardless of age or sex. However, research suggest that fluctuations in female hormones over the menstrual cycle influence the ARR.

Objective: To characterise variations in the ARR according to age and sex.

Methods: A retrospective analysis of 466 clinically indicated ARRs at Monash Health from December 2016 – June 2018 was conducted.  Patients who were on spironolactone, oral contraceptive pill, pregnant or had a known adrenal condition (including untreated PA) were excluded.

Results: Among patients aged 20-39 years (N=74), females had significantly higher median aldosterone (373.5 vs 231 pmol/L, p=0.017), lower median renin (16.5 vs 23.5 mIU/L, p=0.004), and higher median ARR (20.75 vs 10.49, p<0.001) than males. However, females had lower median systolic (135 vs 145 mmHg, p=0.021) and diastolic (89 vs 96.5 mmHg, p=0.007) blood pressure (BP) than males. These sex differences were not observed in the 40 – 59 years (n=161) or 60 – 79 years (n=157) age groups.

Females were then divided into pre- and post-menopausal groups with an arbitrary cut-off at age 45.  Women ≤45 years had significantly higher median aldosterone levels (364 vs 273 pmol/L, p=0.047), lower systolic BP (139 vs 148 mmHg, p=0.002), but higher diastolic BP (89.5 vs 80 mmHg, p=0.001) than those aged >45.

Conclusion: The ARR is significantly higher in pre-menopausal women but not associated with higher systolic BP, suggesting the potential for false positive results if a single ARR reference range is applied to both sexes at all ages. Our findings highlight the need for age- and sex-specific ARR reference ranges, particularly for premenopausal women, to increase the specificity of the ARR when screening for PA.