Lesson
Confirming True Resistant Hypertension
Resistance is a verified phenotype. Apparent resistance may still reflect inaccurate measurement, white-coat effect, incomplete exposure, inadequate doses, or a noncomplementary regimen.
- Apparent versus true resistance
- Controlled resistance
- Outside-office confirmation
- Optimized complementary regimen
Exclude technique and white-coat effect
Confirm complementary therapy and exposure
Find solvable causes before adding treatment
Use maximally tolerated complementary classes
Use the definition precisely
True resistant hypertension includes pressure above goal despite three complementary agents at maximum or maximally tolerated doses, commonly a long-acting dihydropyridine calcium-channel blocker, an ACE inhibitor or ARB, and a diuretic. Pressure controlled with at least four agents also represents a resistant phenotype.
Keep apparent resistance separate
When dose, adherence, or out-of-office pressure is missing, the correct term is apparent treatment-resistant hypertension. This distinction protects the patient from escalation before white-coat effect, nonuse, and inadequate treatment have been excluded.
Confirm usual pressure exposure
Use standardized office measurement plus validated home monitoring or ambulatory monitoring. Out-of-office data separate sustained uncontrolled pressure from a treated white-coat effect and can identify masked uncontrolled hypertension.
Verify the actual regimen
List each active ingredient, formulation, dose, schedule, duration, missed exposure, adverse effect, and refill barrier. Three medicines do not establish resistance when they duplicate a pathway, use inadequate doses, or lack an effective diuretic.
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Lesson
Contributors, Interference, and Pseudoresistance
A difficult pressure often reflects several interacting causes: sodium and volume, medicines that raise pressure, access, regimen burden, pain, sleep, alcohol, substances, or inconsistent exposure.
- Medication exposure
- Interfering medicines and substances
- Sodium and volume
- Access and regimen design
Verify long-acting DHP CCB, ACE inhibitor or ARB, and diuretic
Ask without blame
Match each exposure to its mechanism
Simplify and support before intensifying
Assess exposure without blame
Use open questions, refill history, pill and bottle review, adverse-effect history, and selected biochemical testing when justified. A presence assay can show recent exposure but cannot prove regular therapeutic use over time.
Find medicines that oppose control
Review NSAIDs, decongestants, prescription stimulants, MAO inhibitors, SNRIs, tricyclic antidepressants, selected hormonal therapies, calcineurin inhibitors, erythropoiesis-stimulating agents, glucocorticoids, some oncology therapies, supplements, nicotine, alcohol, and other substances. The timing of exposure and pressure change matters. Ask about abrupt clonidine or tizanidine withdrawal; coordinate medication changes with the prescriber rather than advising sudden discontinuation. Essential therapy may require continued use with better blood-pressure treatment.
Connect the exposure to its mechanism
Sympathomimetics can increase adrenergic tone, NSAIDs can promote sodium retention and blunt several antihypertensive pathways, estrogen-containing therapy can alter hepatic angiotensinogen, calcineurin inhibitors can increase renal and vascular resistance, erythropoiesis-stimulating therapy can raise pressure, and vascular endothelial growth factor pathway inhibition can injure endothelial regulation. The response should fit the indication, mechanism, alternatives, and risk of abrupt withdrawal.
Assess sodium and volume biology
Excess dietary sodium, kidney dysfunction, NSAID exposure, inadequate diuretic delivery, and aldosterone activity can expand volume and blunt other medicines. Use diet, weight, edema, orthostasis, kidney function, electrolytes, and diuretic response together.
Repair the treatment system
Simplify schedules, use appropriate single-pill combinations, synchronize refills, reduce cost, address language and literacy, and change intolerable therapy. Adding drugs to an inaccessible regimen usually adds harm rather than control.
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Lesson
Secondary Hypertension Screening Architecture
Secondary hypertension workup starts with the phenotype. Age of onset, tempo, potassium, kidney and urine data, sleep pattern, medicines, physical examination, and episodic symptoms determine the useful tests.
- Pretest probability
- Common causes
- Abrupt and severe phenotypes
- Actionable testing
Use renal, electrolyte, and renin-aldosterone data
Snoring, witnessed apnea, sleepiness, obesity
Abrupt change, flash edema, asymmetric disease
PA screening plus clue-directed testing for other causes
Build the phenotype first
Record age at onset, abrupt worsening, family history, pressure pattern, potassium, kidney function, urinalysis, albuminuria, pulse, body habitus, sleep symptoms, medication exposures, endocrine features, vascular examination, and target-organ injury.
Prioritize common and treatable causes
Primary aldosteronism, kidney parenchymal disease, obstructive sleep apnea, renovascular disease, and drug or substance effects account for much of the actionable work. Less common endocrine and structural causes require stronger clues.
Match the test to the clue
An aldosterone-renin screen, sleep study, kidney evaluation, vascular imaging, thyroid testing, metanephrine testing, cortisol testing, or aortic imaging each has distinct preparation, false-positive risks, and downstream decisions.
Avoid indiscriminate panels
Low-pretest-probability testing produces incidental and borderline results that can lead to repeated imaging or procedures. A focused workup is broader when onset is young, pressure is abrupt or severe, or true resistance and organ damage are present.
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Lesson
Primary Aldosteronism
Primary aldosteronism is an underdiagnosed spectrum of autonomous aldosterone production with suppressed renin, sodium retention, cardiovascular risk, and sometimes hypokalemia.
- Aldosterone and renin screening
- Potassium and medication effects
- Subtype evaluation
- Surgery versus MRA therapy
Measure potassium for interpretation
Posture, time, sodium, and laboratory method matter
Use expert confirmation and subtype evaluation
Match therapy to subtype and candidacy
Screen with aldosterone and renin
The 2025 Endocrine Society guideline conditionally suggests screening all individuals with hypertension when resources and capacity support it. Screening measures aldosterone and renin and calculates their ratio. Potassium is measured to support interpretation, not as the screening test itself.
Prepare and interpret the sample
Obtain aldosterone and renin in the morning with the patient seated; avoid dietary sodium restriction in the preceding few days. Measure potassium alongside them. Correct hypokalemia and repeat a negative screen when appropriate because low potassium can suppress aldosterone. Interpret the actual hormone values, ratio, assay, kidney function and clinical probability together.
Interpret potassium before dismissing a screen
Potassium does not screen for primary aldosteronism by itself. A normal result does not exclude disease, and low potassium can suppress aldosterone enough to hide an abnormal pattern. If screening is negative with hypokalemia, correct potassium to the laboratory reference range and repeat screening. Review medicines and diuretic exposure as part of the potassium evaluation; check magnesium when hypokalemia resists correction. Interpret the hormone results alongside testing conditions and clinical probability.
Choose a safe medication-testing strategy
The 2025 Endocrine Society guideline provides no-withdrawal and withdrawal approaches according to safety and feasibility. Under minimal withdrawal, MRAs and ENaC inhibitors such as amiloride or triamterene are stopped four weeks before testing; beta blockers and central alpha-2 agonists are stopped two weeks before testing. Arrange substitutions and any necessary taper with the prescriber; these testing intervals do not authorize abrupt clonidine or beta-blocker cessation.
Revisit a result affected by medicines
A negative screen during interfering treatment may need repetition when suspicion remains high. Beta blockers and central alpha-2 agonists can suppress renin and produce a false-positive ratio. Medication withdrawal is not a prerequisite for every initial screen; document the chosen strategy and interpretation limits.
Confirm and determine subtype
The need for suppression testing depends on the screening pattern and clinical setting. Patients pursuing surgery generally need expert subtype evaluation. Cross-sectional imaging identifies anatomy, but adrenal venous sampling is often required because incidental nodules do not establish laterality.
Treat the aldosterone source
Unilateral disease may be treated with adrenalectomy in a suitable surgical candidate. Bilateral disease or nonsurgical care uses a mineralocorticoid receptor antagonist. Monitor pressure, potassium, kidney function, and product-specific adverse effects.
Monitor receptor blockade early
Review baseline potassium, creatinine, blood pressure and volume before selecting an MRA. For spironolactone, check potassium within one week of initiation or titration and regularly thereafter. For eplerenone, measure potassium before starting, within the first week, and at one month after starting or changing the dose, then periodically. Kidney dysfunction and potassium-raising medicines can require more frequent monitoring. Eplerenone labeling also calls for potassium and creatinine checks within three to seven days after starting an ACE inhibitor, ARB, NSAID or moderate CYP3A inhibitor.
Match safeguards to the medicine and indication
Review pregnancy context, kidney function, baseline potassium, interacting medicines, potassium supplements and potassium-containing salt substitutes. Spironolactone can cause gynecomastia and is contraindicated with eplerenone. Eplerenone is contraindicated in all patients with starting potassium above 5.5 mEq/L, creatinine clearance at or below 30 mL/min or strong CYP3A inhibitors. Its hypertension exclusions additionally include creatinine clearance below 50 mL/min, type 2 diabetes with microalbuminuria, creatinine above 2.0 mg/dL in males or 1.8 mg/dL in females, and potassium supplements or other potassium-sparing diuretics. Use the restrictions for the actual indication; receptor selectivity does not remove hyperkalemia risk.
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Lesson
Renal, Sleep, Endocrine, and Structural Causes
Kidney disease, renovascular disease, sleep apnea, thyroid disease, cortisol excess, catecholamine-secreting tumors, and vascular anatomy produce different patterns and require different tests.
- Renal parenchymal and renovascular disease
- Obstructive sleep apnea
- Endocrine testing
- Coarctation and rare causes
Urine, kidney function, imaging when indicated
Sleep testing follows a compatible phenotype
Use clue-specific biochemical preparation
Examination and age of onset guide testing
Separate parenchymal from renovascular disease
Kidney function, urinalysis, albuminuria, structural history, and volume help define renal parenchymal disease. Abrupt worsening, flash pulmonary edema, asymmetric kidney findings, diffuse vascular disease, or a marked creatinine response to RAAS blockade can support renovascular imaging when the result would change care.
Recognize obstructive sleep apnea
Snoring, witnessed apnea, sleepiness, resistant pressure, obesity, and compatible anatomy support sleep evaluation. A screening score estimates probability but does not establish the diagnosis. Treatment addresses sleep, symptoms, safety, and cardiovascular risk alongside blood pressure therapy.
Prepare endocrine testing correctly
Thyroid testing follows thyroid clues. Metanephrine testing requires attention to posture, stress, medicines, and acute illness. Cortisol testing uses accepted circadian or suppression strategies rather than a random cortisol. Exogenous glucocorticoids must be identified before an endogenous workup. Hypercalcemia, kidney stones, bone disease, or compatible symptoms should prompt confirmation of calcium status and a parathyroid-focused evaluation rather than an indiscriminate hormone panel.
Select a metanephrine test deliberately
For suspected pheochromocytoma or paraganglioma, initial testing uses plasma free metanephrines or urinary fractionated metanephrines. For plasma sampling, use at least 30 minutes of supine rest and reference intervals matched to that posture. Review stress, acute illness and interfering medicines. A positive result requires follow-up based on its magnitude and the presentation; a borderline elevation alone does not establish a tumor.
Choose a suitable cortisol screen
After reviewing exogenous steroid exposure, options include at least two 24-hour urinary free cortisol measurements, two late-night salivary measurements, or an overnight 1-mg dexamethasone suppression test. Test choice matters: renal impairment can lower urinary cortisol, variable sleep schedules can undermine late-night sampling, and medicines can alter dexamethasone clearance. An abnormal screen needs endocrine follow-up rather than immediate tumor localization.
Use examination to find structural disease
Young onset, upper-lower extremity pressure differences, delayed femoral pulses, or a murmur can suggest coarctation. Other rare causes follow their own phenotypes. The physical examination remains a high-value localization tool.
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Lesson
Stepwise Resistant Hypertension Treatment
Treatment begins by optimizing the complementary three-drug base, sodium and volume management, and exposure. Mineralocorticoid receptor blockade is a common fourth step, while additional drugs and devices require careful selection.
- Optimized three-drug base
- Mineralocorticoid receptor antagonist
- Later add-on therapy
- Specialist and renal denervation evaluation
Use maximally tolerated doses
Monitor potassium, kidney function, and pregnancy
Match heart rate, volume, kidney, and comorbidity
Renal denervation requires team evaluation and shared decisions
Optimize the foundation
Use maximally tolerated complementary therapy, commonly a long-acting dihydropyridine calcium-channel blocker, an ACE inhibitor or ARB, and an effective diuretic. Long-acting thiazide-like therapy may strengthen the base when kidney function and safety permit.
Target aldosterone biology
The 2025 AHA/ACC recommendation to add an MRA after optimized ACE inhibitor or ARB, CCB and thiazide-like therapy specifies eGFR at least 45 mL/min/1.73 m2. Spironolactone is commonly used. Below this threshold, seek individualized specialist assessment rather than automatically applying the routine pathway or treating 45 as a universal contraindication. Check potassium, pregnancy context, interactions and product labeling; arrange early repeat laboratory monitoring.
Keep eplerenone restrictions indication specific
For hypertension, eplerenone is contraindicated with creatinine clearance below 50 mL/min, type 2 diabetes with microalbuminuria, creatinine above 2.0 mg/dL in males or 1.8 in females, or potassium supplements or other potassium-sparing diuretics. General exclusions also include starting potassium above 5.5 mEq/L, creatinine clearance at or below 30 and strong CYP3A inhibitors. Do not substitute an HFrEF eligibility threshold or eGFR value for these label criteria.
Individualize later therapy
Additional treatment may include agents selected by heart rate, sympathetic activity, volume, kidney function, heart failure, coronary disease, tolerability, and access. Aprocitentan provides a newer endothelin pathway but carries embryo-fetal toxicity and fluid-retention risks and does not replace standard optimization.
Use the labeled aprocitentan regimen
Tryvio is an adult add-on therapy: 12.5 mg orally once daily, with or without food. Swallow whole; skip a missed dose rather than doubling that day. Blood-pressure lowering is established, but its label reports no controlled trials demonstrating fewer cardiovascular events with Tryvio itself.
Apply reproductive precautions
Pregnancy and hypersensitivity are contraindications. Exclude pregnancy before starting; use effective contraception before, during and for one month after treatment. Stop promptly if pregnancy occurs. Advise against breastfeeding and discuss possible sperm-count effects.
Monitor beyond the pressure response
Check aminotransferases, bilirubin and hemoglobin before treatment and periodically afterward. Do not start with aminotransferases above three times the upper limit or moderate-to-severe hepatic impairment; severe anemia also argues against initiation. Suspected liver injury requires stopping and medical assessment. Monitor weight, edema and worsening heart failure. Use is not recommended with NYHA III to IV heart failure, unstable cardiac function or NT-proBNP at least 500 pg/mL. Significant fluid retention requires treatment and consideration of discontinuation.
Apply renal-denervation selection criteria
The 2025 AHA/ACC guideline says adjunctive renal denervation may be reasonable for selected patients with office systolic pressure 140 to 180 mm Hg, diastolic pressure at least 90 mm Hg and eGFR at least 40 mL/min/1.73 m2, with resistance despite optimal treatment or intolerable additional-drug adverse effects. This is a conditional option requiring expert assessment, not automatic eligibility.
Check the exact device exclusions
Paradise labeling excludes renal artery fibromuscular dysplasia, a stented artery, aneurysm, stenosis over 30 percent, or diameter outside 3 to 8 mm. Pregnancy, abnormal kidney or secreting adrenal tumors, and access-vessel stenosis preventing insertion also exclude use. These product-specific restrictions require anatomy and clinical review before a procedure.
Use specialists and devices deliberately
Persistent uncontrolled pressure warrants hypertension-specialist evaluation. Renal denervation is an adjunctive option for selected patients after multidisciplinary confirmation, secondary-cause evaluation, anatomy review, and shared discussion of expected benefit, uncertainty, procedural risk, medicines, and continued follow-up.
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Module practice
Check the connections.
Each attempt draws 10 questions from the complete 116 question bank.
Each attempt draws a fresh set and rearranges the answer choices.
References
Current clinical foundation.
Core source material was synthesized with the following contemporary guidance. Verify local policy and current guidance before applying clinical information.
- INSPRA prescribing information: indication-specific contraindications
- Endocrine Society. Pheochromocytoma and paraganglioma guideline: biochemical testing
- Endocrine Society. Diagnosis of Cushing syndrome: initial tests and limitations
- AHA and ACC. 2025 High Blood Pressure Guideline
- Endocrine Society. 2025 Primary Aldosteronism Guideline
- American Heart Association. Resistant Hypertension Scientific Statement
- FDA. Paradise Ultrasound Renal Denervation System
- DailyMed. Tryvio prescribing information, August 2026
- Pfizer. ALDACTONE prescribing information, revised November 2025
- RxPrep 2023 Course Book
Chapter 28, printed pages 434 and 442 (PDF pages 442 and 450), secondary hypertension and aldosterone context; Chapter 53, printed page 709 (PDF page 717), hypokalemia causes and magnesium-dependent correction.