We demystify primary aldosteronism, MRAs (mineralocorticoid receptor antagonists), non-steroidal MRAs, and how to recognize and treat renovascular hypertension with nephrologist/hypertension expert, Dr. Matt Luther (@DrJMLuther) as part of the NephMadness PodCrawl 2023. Fill out a bracket for NephMadness and check out all eight NephMadness PodCrawl participants at NephMadness.com/podcrawl (list below) and the MRA region write-up by Micah Schub (@AcidBassMD).
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PA is a common reason for resistant hypertension in Dr. Luther’s hypertension clinic. It’s caused by the inappropriate production of aldosterone by the adrenal gland which makes the kidneys reabsorb salt and excrete potassium. About half the time it’s due to a nodule that can be removed surgically and about half the time it is treated with medications.
Testing for PA is recommended for all patients with resistant hypertension. Further, some experts recommend testing all patients with primary hypertension (HTN) at least once for primary aldosteronism (Young, 2019). Check an early morning plasma aldosterone concentration (PAC), and plasma renin activity (PRA) or plasma renin concentration (PRC). Hypertension, intermediate or elevated aldosterone levels, and suppressed renin are suggestive of primary aldosteronism (Young, 2019). Further, suppressed renin in a patient on a thiazide diuretic, and ACEI/ARB is suspicious for primary aldosteronism (PA).
Spontaneous or provoked hypokalemia is not always present in primary aldosteronism (Young, 2019).
Dr. Luther performs the following investigations when primary aldosteronism is suspected.
Aldosterone excess causes glomerular hyperfiltration (Young, 2019). Thus, patients with PA often have underlying renal dysfunction that is not reflected by their pretreatment creatinine. Once aldosterone is adequately suppressed and hyperfiltration goes away, patients will have a rise in serum creatinine as their renal dysfunction is “unmasked” (Young, 2019). In the long run, this is a good thing, but patients and clinicians should be prepared for eGFR to drop (Utsumi, 2017) and for creatinine to settle at a new, higher baseline. Utsumi and colleagues developed nomograms to predict patients who will experience a >25% postoperative decrease in eGFR or new eGFR <45 ml/min.
Dr. Luther notes patients should still get first-line hypertension agents (Calcium channel blocker, ACEI/ARB, and a diuretic) before adding spironolactone.
Spironolactone can be started at 12.5 mg daily, and a metabolic panel should be checked in about 1-2 weeks to monitor creatinine and potassium (Young, 2019). Dr. Luther’s practice includes checking renin, which will rise once a patient is successfully treated with an MRA. He notes that spironolactone doses in CKD are limited by hyperkalemia, but in patients without CKD doses of 100-200 mg per day are commonly reached.
Due to its short half-life, eplerenone should be dosed twice daily and is typically started at 25 mg twice daily (Young, 2019). It is only about half as potent as spironolactone and doses of 200-300 mg daily may be needed. Eplerenone has less binding affinity at androgen receptors and is less likely to cause gynecomastia (Young, 2019). Dr. Luther recommends allowing spironolactone to “wash out” for a few days before starting eplerenone (expert opinion). Dr. Luther has run into issues with pharmacies not wanting to fill higher doses because it’s only FDA-approved for 100 mg per day, and/or due to high cost.
Kashlak Pearl: Trimethoprim-sulfamethoxazole can cause severe hyperkalemia if combined with spironolactone (Antoniou, 2015), amiloride, or other agents that raise potassium. Warn your patients and proceed with caution!
Finerenone is the first non-steroidal approved for use in patients with diabetes, CKD, and proteinuria based on FIDELIO (Bakris, 2020) and FIGARO (Pitt, 2021). It has not been approved for PA, and as of this writing, no trials are registered at clinicaltrials.gov. Finerenone has less hyperkalemia, but also less blood pressure lowering effect (Agarwal, 2023) than spironolactone (Agarwal (AMBER), 2019).
We must be selective about who we work-up for renovascular hypertension because revascularization is not more effective than medical therapy in most patients (ACC/AHA guidelines by Bhalla, 2022). First, treat medically. Don’t look for renovascular hypertension unless patients can’t be controlled medically or exhibit certain clinical syndromes (Bhalla, 2022) e.g. fibromuscular dysplasia (FMD) with hypertension, hypertensive encephalopathy, flash pulmonary edema or suspicion for bilateral renal artery stenosis* with worsening renal function.
*Kashlak Pearl: Dr. Luther suspects bilateral renal artery stenosis in a patient with severe hypertension who develops a decline in renal function once blood pressure is reduced followed by another rise in blood pressure followed by another decline in renal function when the blood pressure is controlled. This cycle repeats over time.
A stenosis from renovascular disease must be severe (often >70% stenosis) to cause ischemic injury to the kidney (Bhalla, 2022 figure 2). Dr. Luther looks at a patient’s prior imaging for a discrepancy in kidney size**. He prefers CT angiogram to ultrasound or MRI when looking for renovascular disease (expert opinion). In Dr. Luther’s opinion renal duplex ultrasound can be misleading and should be interpreted by experienced radiologists. He often repeats imaging because in his experience an ischemic kidney can change in size over the course of months. In the case of FMD, patients might require invasive angiography for proper hemodynamic assessment to assess the need for angioplasty (Bhalla, 2022).
**Kashlak Pearl: Dr. Luther points out that kidney size discrepancy can be caused by things other than renovascular disease e.g. prior infection, stone disease, or congenital diseases including sickle cell or thalassemia (Davran, 2014). Suspect renovascular disease in patients with traditional vascular risk factors such as vascular disease in other territories (e.g. low ankle-brachial index).
Fibromuscular dysplasia can present later in life, but the classic patient is a younger woman with early-onset, accelerated, malignant, or resistant hypertension, a small kidney without uropathy, or arterial bruit on exam (abdomen, flank, or neck, or FMD in another vascular territory) –(Bhalla, 2022).
Renovascular hypertension is a cardiovascular risk equivalent (Wollenweber, 1968; Weber, 2014) and should be treated with aggressive risk reduction (lipid-lowering, smoking cessation, lifestyle changes, etc.). The approach to blood pressure treatment is similar to that in patients without renovascular hypertension. Renal function should be monitored closely (Bhalla, 2022).
ASTRAL and CORAL were negative trials of revascularization for renal artery stenosis. Invasive treatment is reserved for highly selected patients and may include stenting, angioplasty, or open bypass (Bhalla, 2022).
Hypertension Secrets (book) by EV Lerma, JM Luther, S Hiremath
Listeners will discuss primary aldosteronism, MRAs, and renovascular hypertension
After listening to this episode listeners will…
Dr. Luther reports the following disclosures – Mineralys: membership on advisory committees or review panels, board membership, etc (relationship has not ended); Bayer: honoraria (relationship has ended); American Heart Association: membership on advisory committees or review panels, board membership, etc (relationship has not ended); Elsevier – Hypertension Secrets: royalties or patent beneficiary (relationship has not ended). The Curbsiders report no relevant financial disclosures.
Watto MF, Luther JM, Williams PN. “#386 Primary Aldosteronism, MRAs, and Renovascular Hypertension: NephMadness Pod Crawl 2023”. The Curbsiders Internal Medicine Podcast. https://thecurbsiders.com/episode-list Final publishing date March 20, 2023.
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