It is not cost effective to screen everyone for secondary hypertension
However, we should consider screening when:
1. Age <30 in non-obese with no family history
2. Acute rise compared to previously stable
3. Severe or resistant HTN
4. Associated with electrolyte abnormalities
5. Signs of end-organ damage from accelerated HTN
When considering secondary HTN – verify blood pressures with home BP monitoring, evaluate medications that can cause HTN (NSAIDS, OCP, Steroids).
Top 3 causes of secondary HTN are renovascular disease, primary hyperaldosteronism, OSA.
Additional considerations are renal parenchymal disease, thyroid disorders, pheochromocytoma, Cushing disease, aortic coarctation, and genetic disorders.
Several mechanisms of HTN tie back into the RAS system. PATHWAY – 2 trial showed efficacy of mineralocorticoid receptor antagonists for resistant HTN. Some suggest MRAs should have greater role in BP management overall.
Suspect if patient has diffuse atherosclerosis, renal asymmetry, recurrent flash pulmonary edema, or an acute rise in creatinine >30% after starting a RAS inhibitor.
Two trials have influenced our current thinking: ASTRAL (2009) and CORAL (2014)
Randomized medical therapy vs stenting + medical therapy and there was no improvement in mortality or kidney/CV outcomes.
Now, we consider further screening only if it will impact our approach. Typically, this is a patient who has failed medical therapy and has had recurrent episodes of acute pulmonary edema.
Screening can be done with US, CTA, MRA
Medical therapy consists of ACE/ARB (increase in creatinine <30%, can continue therapy)
Surgical therapy is done with percutaneous angioplasty with stenting
Possible that new techniques have improved outcomes from surgery, however no major trials have been done to recommend this. (no touch technique, embolic protection devices)
Thought of as a “rare” disease by many clinicians, however it is likely that we are just not very good at screening for this.
Classic triad is HTN, hypokalemia, metabolic alkalosis. However, can be normokalemic.
Testing consists of morning renin and aldosterone. Can screen using ratio of >20:1 or using paired testing looking for renin activity <1 and aldosterone >10.
Some suggest that the ratio >20 is an arbitrarily high number and not an effective screen for hyperaldo.
Need to consider their medications when pursuing testing – some will affect measurement. (RASi, MRA)
May consider confirmatory testing if lab results are equivocal.
Subtype analysis uses a CT to look at the consistency of adrenals. Attempts to delineate between adrenal adenoma, bilateral hyperplasia (most common), and possible carcinoma.
Further testing with adrenal vein sampling can be pursued to identify unilateral vs bilateral disease.
Unilateral can potentially undergo laparoscopic adrenalectomy for curative intent.
Bilateral disease is controlled with MRA
Brown, JM et al (2020). The Unrecognized Prevalence of Primary Aldosteronism: A Cross-sectional Study. Annals of Internal Medicine.
Muntner, P et al (2018). Potential US population impact of the 2017 ACC/AHA high blood pressure guideline. Journal of the American College of Cardiology, 71(2), 109-118.
Cooper, CJ et al (2014). Stenting and medical therapy for atherosclerotic renal-artery stenosis. New England Journal of Medicine, 370(1), 13-22.
Astral Investigators. (2009). Revascularization versus medical therapy for renal-artery stenosis. New England Journal of Medicine, 361(20), 1953-1962.
Prince, M., Tafur, J. D., & White, C. J. (2019). When and how should we revascularize patients with atherosclerotic renal artery stenosis?. JACC: Cardiovascular Interventions, 12(6), 505-517.
Young, WF et al (2020). Diagnosis of primary aldosteronism. UpToDate. Post TW, ed. Waltham, MA: UpToDate Inc. http://www.uptodate.com (Accessed on December 31, 2020.)
Textor, S et al (2020). Evaluation of secondary hypertension. UpToDate. Post TW, ed. Waltham, MA: UpToDate Inc. http://www.uptodate.com (Accessed on December 31, 2020.)
Textor, S et al (2020). Establishing the diagnosis of renovascular hypertension. UpToDate. Post TW, ed. Waltham, MA: UpToDate Inc. http://www.uptodate.com (Accessed on December 31, 2020.)