Rates of abnormal aldosterone/renin ratio in African-origin compared to European-origin patients: A retrospective study

How common is primary aldosteronism?

PURPOSE OF REVIEW

Primary aldosteronism, characterized by renin-independent aldosterone secretion from one or both adrenal glands, is the most common and modifiable form of secondary hypertension. The prevalence of primary aldosteronism is increasingly recognized to be much higher than previously thought with many cases still undetected.

RECENT FINDINGS

Prior prevalence studies on primary aldosteronism have reported a wide range of estimates due to heterogeneity of both disease definitions and study populations such that it is difficult to claim a single point estimate. More recent evidence demonstrates that primary aldosteronism, as defined by conventional biochemical diagnostic criteria, is highly prevalent within populations where it is not typically considered such as mild-to-moderate hypertension, prehypertension, and even normotension. Yet, our current screening approach fails to capture many cases. Furthermore, there is mounting evidence that renin-independent aldosteronism exists as a continuum of disease that extends below the current biochemical diagnostic thresholds used to define primary aldosteronsim and has clinically relevant treatment and outcome implications for a much broader patient population. Indeed, much of what we current label as 'essential hypertension' is, in fact, renin-independent aldosterone-mediated hypertension.

SUMMARY

Primary aldosteronism and milder forms of renin-independent aldosteronism are highly prevalent, yet vastly under-recognized, in the general population.

Clinical presentation and surgical outcomes in primary aldosteronism differ by race

BACKGROUND

Primary aldosteronism (PA) is the most common cause of secondary hypertension; early diagnosis and intervention correlate with outcomes. We hypothesized that race may influence clinical presentation and outcomes.

METHODS

We conducted a retrospective analysis of patients with PA (1997-2017) who underwent adrenal vein sampling (AVS). Patients were classified by self-reported race as black or non-black. Improvement was defined as postoperative decrease in mean arterial pressure (MAP), antihypertensive medications (AHM), or both.

RESULTS

Among patients undergoing AVS (n = 443), 287 underwent adrenalectomy. Black patients (28.2%) had higher body mass index (33.9 vs 31.8 kg/m² ; P = .01), longer median duration of hypertension (12 vs 10 years; P = .003), higher modified Elixhauser comorbidity index (2 vs 1; P = .004), and lower median income ($47 134 vs $78 280; P < .001). Black patients had similar aldosterone:renin ratios (150 vs 135.6 [ng/dL]/[ng·mL·^-1 hr^-1 ]; P = .23) compared to non-blacks. At long-term follow-up, black patients had a similar requirement for AHM (1 vs 0; P = .13) but higher MAP (100.6 vs 95.3 mm Hg; P = .004).

CONCLUSION

Black patients present with longer duration of hypertension and more comorbidities. They are equally likely to lateralize on AVS, suggesting similar disease phenotype. However, black patients demonstrate less improvement with adrenalectomy; this may reflect a delay in diagnosis or concomitant essential hypertension.

The aldosterone to renin ratio in the diagnosis of primary aldosteronism: Promises and challenges

The complexity of evaluating patients for secondary treatable causes of hypertension is underappreciated. Primary aldosteronism (PA) is the most prevalent cause of secondary hypertension (3%-32% of hypertensive patients). The recent endocrine society clinical practice guideline (ESCPG), "The Management of Primary Aldosteronism: Case Detection, Diagnosis, and Treatment", differs from the previous version in the explicit recognition of PA as a major public health issue. Despite this, PA is underdiagnosed. The guidelines call on physicians to substantially ramp up the screening of hypertensive patients at risk of PA. Further, it recommends the plasma aldosterone to renin ratio (ARR), as the test of choice for screening for PA. However, the ARR is a highly variable test with reported diagnostic sensitivities and specificities ranging from 66% to 100% and 61% to 100%, respectively. Variability of the ARR can be attributed to the high degree of within-subject variation, differences in sampling protocols, laboratory assays, reporting units, the effect of medications and the population characteristics used to establish the decision thresholds. These factors render the possibility of false positive and false negative results-which have the potential to adversely impact patients. The limitations and caveats to the use of the ARR necessitate an effective clinic-laboratory interface, with specialist physician and clinical scientist collaboration for ARR result interpretation. Improvement in the diagnostic sensitivity and specificity of the ARR is predicated on harmonisation of pretesting patient preparation criteria, knowledge of the analytical methods used to derive the ratio and the method-specific threshold for PA.