Primary aldosteronism Medical Services in China

Primary aldosteronism (PA), also known as Conn’s syndrome, is a common and potentially curable form of secondary hypertension caused by autonomous overproduction of aldosterone from the adrenal glands—most frequently due to an aldosterone-producing adenoma (APA) or bilateral adrenal hyperplasia (BAH). Unlike physiological aldosterone secretion—which is tightly regulated by the renin-angiotensin system and potassium levels—PA involves dysregulated, excessive mineralocorticoid activity. This leads to sodium retention, potassium wasting, plasma volume expansion, and suppression of plasma renin activity. The resulting chronic hypertension is often resistant to conventional antihypertensive therapy and carries significantly higher cardiovascular morbidity and mortality compared to essential hypertension, including increased risks of left ventricular hypertrophy, atrial fibrillation, stroke, and chronic kidney disease. Epidemiologically, PA affects approximately 5–10% of all patients with hypertension, rising to 15–20% among those with resistant hypertension (defined as uncontrolled BP despite ≥3 antihypertensives, including a diuretic). It is underdiagnosed globally; screening is recommended for patients with early-onset hypertension (<40 years), spontaneous or diuretic-induced hypokalemia, adrenal incidentaloma, family history of PA or early-onset stroke, or hypertension with sleep apnea. Key risk factors include obesity, metabolic syndrome, advancing age (peak incidence 30–50 years), and genetic predispositions such as germline mutations in KCNJ5, CACNA1D, or ATP1A1—though most cases are sporadic. Importantly, PA is not rare in normotensive individuals with unexplained hypokalemia or recurrent nephrolithiasis. Quality of life is substantially impaired: patients commonly report fatigue, muscle weakness, nocturia, headaches, palpitations, and cognitive fog—symptoms often misattributed to stress or aging. Untreated PA accelerates end-organ damage and increases healthcare utilization. Early diagnosis via plasma aldosterone-to-renin ratio (ARR) followed by confirmatory testing (e.g., saline infusion test or oral sodium loading) and adrenal imaging (CT/MRI) enables targeted management—either surgical adrenalectomy for unilateral disease or mineralocorticoid receptor antagonists (e.g., spironolactone or eplerenone) for bilateral or non-surgical cases. With appropriate intervention, blood pressure control improves markedly, potassium normalizes, and cardiovascular risk declines significantly. Patient education, long-term monitoring of electrolytes and renal function, and multidisciplinary care involving endocrinologists, hypertension specialists, and adrenal surgeons are critical to optimizing outcomes.

Primary aldosteronism (PA) is a heterogeneous endocrine disorder characterized by autonomous, excessive production of aldosterone from the adrenal cortex, independent of the renin-angiotensin system. It is the most common identifiable and potentially curable cause of secondary hypertension, affecting approximately 5–10% of patients with hypertension and up to 20% of those with resistant hypertension. The pathophysiology centers on dysregulated mineralocorticoid secretion, leading to sodium retention, potassium wasting, volume expansion, and suppression of plasma renin activity—hallmarks that distinguish PA from essential hypertension.

The two most common causes are unilateral aldosterone-producing adenoma (APA), accounting for ~60% of cases, and bilateral adrenal hyperplasia (BAH), responsible for ~40%. APA arises from a benign, monoclonal adrenal cortical tumor, typically <4 cm in diameter, with somatic gain-of-function mutations in ion channel or pump genes—most notably KCNJ5 (encoding Kir3.4 potassium channel), followed by CACNA1D (L-type calcium channel), ATP1A1 (Na+/K+-ATPase α1 subunit), and ATP2B3 (plasma membrane Ca2+ ATPase). These mutations induce chronic cellular depolarization, calcium influx, and activation of calcium-dependent steroidogenic pathways, resulting in constitutive aldosterone synthesis. BAH reflects diffuse or nodular hyperplasia of zona glomerulosa cells; its etiology is less well defined but involves aberrant expression of G-protein-coupled receptors (e.g., AVPR1a, TSHR, LHCGR) that render adrenal cells responsive to non-physiological ligands such as vasopressin, thyroid hormone, or gonadotropins—thereby stimulating aldosterone production outside normal regulatory constraints.

Rare causes include unilateral adrenal carcinoma (<1%), familial forms (familial hyperaldosteronism types I–IV), and primary adrenal lymphoma or metastasis. Familial hyperaldosteronism type I (glucocorticoid-remediable aldosteronism, GRA) results from an unequal crossover between CYP11B1 and CYP11B2 genes, generating a chimeric gene under ACTH-responsive promoter control—hence aldosterone production becomes glucocorticoid-suppressible. Type II (FH-II) is genetically heterogeneous, linked to germline variants in CLCN2 (encoding voltage-gated chloride channel ClC-2) and more recently KCNJ5, though penetrance is incomplete and inheritance is autosomal dominant. FH-III, associated with severe early-onset PA and massive adrenal hyperplasia, stems from germline KCNJ5 mutations (e.g., G151R, T158A); FH-IV involves germline CACNA1D mutations causing severe hypertension and neuromuscular abnormalities.

Triggers are not causative per se but may unmask or exacerbate PA: acute hypokalemia (which paradoxically stimulates aldosterone release in some APAs), prolonged dietary sodium restriction (enhancing renin-independent aldosterone sensitivity), or administration of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (which further suppress renin and amplify the aldosterone-to-renin ratio). Stress-induced catecholamine surges may also transiently augment aldosterone output in susceptible adrenal tissue.

Established risk factors include age (peak incidence 30–50 years), female sex (slight predominance), obesity (BMI ≥30 kg/m²), and presence of resistant hypertension (≥3 antihypertensives including a diuretic), spontaneous or diuretic-induced hypokalemia, adrenal incidentaloma, and early-onset or stroke-at-a-young-age hypertension. A family history of PA or early-onset cerebrovascular disease increases suspicion for hereditary forms.

Genetic factors play a pivotal role: somatic mutations drive APA pathogenesis in >70% of cases, while germline variants underlie familial syndromes. Emerging evidence implicates polymorphisms in genes regulating adrenal zonation (e.g., NR4A2, NROB1) and steroidogenesis (e.g., STAR, CYP11B2 promoter variants) as potential susceptibility modifiers. Epigenetic dysregulation—including aberrant DNA methylation at the CYP11B2 locus—has been observed in APA tissue, suggesting additional layers of transcriptional control.

Environmental factors remain poorly defined but likely contribute to phenotypic expression. Chronic high-sodium intake may accelerate target-organ damage without altering aldosterone production itself, whereas low-sodium diets can exaggerate biochemical abnormalities during screening. Exposure to endocrine-disrupting chemicals (e.g., bisphenol A, phthalates) has been hypothesized to interfere with adrenal steroidogenic enzyme function or receptor signaling, though human epidemiologic data are limited. Smoking and chronic psychological stress may potentiate vascular injury and amplify cardiovascular morbidity in PA, but do not initiate aldosterone overproduction. Importantly, PA is not associated with lifestyle factors such as alcohol use or physical inactivity in a causal manner—though these influence overall cardiovascular risk burden. Early diagnosis via plasma aldosterone concentration-to-renin activity ratio (ARR), confirmatory testing (e.g., saline infusion, oral sodium loading), and adrenal vein sampling remains critical to guide targeted treatment—either adrenalectomy for unilateral disease or mineralocorticoid receptor antagonists (e.g., spironolactone, eplerenone) for bilateral or nonsurgical cases.

Primary aldosteronism (PA), also known as Conn’s syndrome when caused by a unilateral aldosterone-producing adenoma, is a common and potentially curable cause of secondary hypertension and hypokalemia. It results from autonomous overproduction of aldosterone by the adrenal zona glomerulosa—either due to a benign unilateral adenoma (60–70% of cases), bilateral adrenal hyperplasia (20–40%), or rare causes such as aldosterone-producing carcinoma (<1%) or familial hyperaldosteronism (types I–IV). As an endocrine disorder managed primarily within Endocrinology, PA carries significant cardiovascular morbidity if undiagnosed or untreated.

Early symptoms are often subtle and nonspecific, contributing to frequent under-recognition. Patients may report persistent fatigue, mild headache, intermittent muscle cramps, or generalized weakness—symptoms frequently attributed to stress, aging, or lifestyle factors. Subtle polydipsia and nocturia may be present due to chronic hypokalemic nephropathy and impaired urinary concentrating ability, though these are rarely isolated or alarming in early stages. Importantly, many patients remain asymptomatic for years; hypertension may be the sole initial manifestation, often presenting as stage 1 or 2 essential-appearing hypertension that is resistant to conventional antihypertensive therapy—particularly diuretics, beta-blockers, or ACE inhibitors alone.

Typical symptoms emerge with progressive mineralocorticoid excess and electrolyte derangement. Sustained hypertension is nearly universal (>95% of cases) and typically manifests as diastolic or systolic-diastolic elevation, often with poor response to ≥3 antihypertensive agents (resistant hypertension). Hypokalemia—present in ~30–50% of patients at diagnosis—is a hallmark biochemical feature but not obligatory; normokalemic PA is increasingly recognized and accounts for up to 40% of cases, especially in those with bilateral disease or milder phenotypes. When present, hypokalemia produces characteristic neuromuscular symptoms: muscle weakness (proximal > distal), transient paralysis (rare but life-threatening), paresthesias, and cramping—often exacerbated by carbohydrate load or diuretic use. Polyuria and polydipsia reflect potassium-induced nephrogenic diabetes insipidus, resulting from downregulation of aquaporin-2 channels in collecting duct principal cells. Metabolic alkalosis may contribute to lightheadedness, confusion, or tetany in severe cases.

Accompanying symptoms reflect multisystem consequences of chronic aldosterone excess and hypertension. Cardiovascular manifestations include left ventricular hypertrophy (LVH), diastolic dysfunction, atrial fibrillation, and increased arterial stiffness—often disproportionate to blood pressure level. Patients may experience exertional dyspnea or palpitations secondary to LVH or arrhythmia. Renal involvement includes microalbuminuria, reduced estimated glomerular filtration rate (eGFR), and chronic kidney disease progression, partly mediated by aldosterone-induced renal fibrosis and podocyte injury. Neurocognitive complaints—including brain fog, impaired concentration, and sleep disturbances—are increasingly documented and correlate with aldosterone levels independent of blood pressure. Sexual dysfunction (erectile dysfunction in men, decreased libido in women) occurs in ~25–35% of patients and may relate to endothelial dysfunction and vascular remodeling. Glucose intolerance and insulin resistance are common comorbidities, with PA associated with a 2–3-fold increased risk of new-onset type 2 diabetes, likely via aldosterone-mediated inhibition of insulin signaling in skeletal muscle and adipose tissue.

Complications arise from prolonged, uncontrolled mineralocorticoid excess. Cardiovascular complications dominate: accelerated atherosclerosis, myocardial fibrosis, heart failure (particularly HFpEF), stroke, and premature coronary artery disease. The risk of major adverse cardiovascular events (MACE) is 2–4 times higher in PA versus essential hypertension matched for age and BP. Renal complications include progressive CKD, nephrocalcinosis (secondary to chronic hypocitraturia and alkalosis), and increased susceptibility to contrast-induced nephropathy. Hypokalemic rhabdomyolysis is rare but possible during acute illness or strenuous exertion. Severe, untreated PA may culminate in hypertensive emergencies, malignant hypertension, or sudden cardiac death. Notably, even after biochemical cure (e.g., adrenalectomy), residual cardiovascular damage may persist, underscoring the importance of early detection.

Diagnosis follows a structured three-step approach: screening, confirmation, and subtype differentiation. Screening begins with plasma aldosterone concentration (PAC) and plasma renin activity (PRA) or direct renin concentration (DRC) measured under standardized conditions (e.g., seated for ≥15 minutes, morning draw, off interfering medications for ≥4 weeks where feasible). The aldosterone-to-renin ratio (ARR) is the cornerstone screening test; an elevated ARR (>20–30 ng/dL per ng/mL/h with PAC >15 ng/dL, or >35–40 with DRC) warrants confirmatory testing. Confirmatory tests assess non-suppressibility of aldosterone: oral sodium loading (2g NaCl tid × 3 days), saline infusion test (2L 0.9% saline IV over 4 hours), fludrocortisone suppression test, or captopril challenge. A post-test PAC >5–6 ng/dL confirms autonomous aldosterone production. Subtype differentiation relies on adrenal vein sampling (AVS)—the gold standard—to distinguish unilateral (adenoma or unilateral hyperplasia) from bilateral disease. CT or MRI adrenal imaging is adjunctive but insufficient alone, given high rates of nonfunctioning incidentalomas (up to 8% in adults) and poor correlation between nodule size and hormonal activity. Genetic testing is indicated for early-onset PA (<20 years), family history, or suspected familial hyperaldosteronism (e.g., glucocorticoid-remediable aldosteronism [GRA], requiring dexamethasone suppression and CYP11B1/B2 chimeric gene analysis).

Differential diagnosis must exclude other causes of hypertension and hypokalemia. Essential hypertension with diuretic-induced hypokalemia is the most common mimic; careful medication review is critical. Other mineralocorticoid excess states include apparent mineralocorticoid excess (AME, due to 11β-HSD2 deficiency), Liddle syndrome (epithelial sodium channel gain-of-function), and exogenous mineralocorticoid administration (e.g., licorice ingestion, carbenoxolone). Cushing syndrome may present with hypertension and hypokalemia but features cortisol excess (central obesity, striae, easy bruising, hyperglycemia) and suppressed ACTH. Renovascular hypertension shows elevated renin (low-normal or high PRA/DRC), unlike PA’s suppressed renin. Bartter and Gitelman syndromes cause hypokalemic metabolic alkalosis but with low/normal aldosterone, high renin, and characteristic urinary electrolyte patterns (elevated urine chloride, calcium, magnesium). Pseudohypoaldosteronism type II (Gordon syndrome) mimics PA clinically but features hyperkalemia—not hypokalemia—and is linked to WNK kinase mutations. Accurate distinction hinges on integrated interpretation of clinical phenotype, electrolytes, hormonal assays, and dynamic testing—not isolated lab values.

Primary aldosteronism (PA) is a common and potentially curable cause of secondary hypertension, characterized by autonomous overproduction of aldosterone from the adrenal glands—most frequently due to an aldosterone-producing adenoma (APA) or bilateral adrenal hyperplasia (BAH). Accurate diagnosis and subtype differentiation are essential before initiating therapy, as treatment strategies differ significantly between unilateral and bilateral disease. Management is guided by international guidelines (e.g., Endocrine Society Clinical Practice Guidelines) and adapted within China’s integrated endocrine care framework.

Conservative treatment is indicated exclusively for patients with confirmed bilateral adrenal hyperplasia (BAH), those who are not surgical candidates due to comorbidities or advanced age, or individuals who decline surgery after thorough counseling. It focuses on long-term blood pressure control and prevention of aldosterone-mediated end-organ damage—including left ventricular hypertrophy, renal fibrosis, and vascular inflammation. Lifestyle modifications form the cornerstone: sodium restriction (<2 g/day), weight optimization, regular aerobic exercise (≥150 min/week moderate intensity), smoking cessation, and moderation of alcohol intake. Dietary potassium supplementation may be considered only under close monitoring, as hyperkalemia risk increases with mineralocorticoid receptor antagonists (MRAs). Home blood pressure monitoring and annual assessment of renal function, serum electrolytes, ECG, and echocardiography are mandatory components of conservative management.

Pharmacologic therapy centers on mineralocorticoid receptor antagonists. Spironolactone remains first-line: initiated at 12.5–25 mg daily, titrated gradually to 25–50 mg twice daily based on blood pressure response, serum potassium (target 4.0–4.8 mmol/L), and creatinine clearance (>45 mL/min). Eplerenone—a more selective MRA with lower antiandrogenic activity—is preferred in men concerned about gynecomastia or women with menstrual irregularities; dosing starts at 25 mg once daily, escalating to 50 mg twice daily. Both agents reduce systolic/diastolic BP by 15–30/10–20 mmHg and improve arterial stiffness and left ventricular mass index. Additional antihypertensives—such as calcium channel blockers (amlodipine) or thiazide-like diuretics (chlorthalidone)—may be added cautiously, avoiding non-dihydropyridine CCBs (e.g., verapamil) that can elevate aldosterone in some contexts. ACE inhibitors or ARBs are generally avoided as monotherapy in PA due to compensatory renin suppression and limited efficacy; however, low-dose ARBs may be used adjunctively in refractory cases under specialist supervision. All pharmacologic regimens require quarterly clinical review and biannual assessment of plasma aldosterone concentration (PAC), plasma renin activity (PRA), estimated glomerular filtration rate (eGFR), and urinary albumin-to-creatinine ratio (UACR).

Surgical treatment—unilateral laparoscopic adrenalectomy—is the definitive therapy for patients with lateralized PA confirmed by adrenal vein sampling (AVS) and imaging (CT/MRI showing a discrete nodule ≥4 cm or with washout characteristics consistent with APA). In experienced centers, laparoscopic adrenalectomy achieves biochemical cure (normalization of PAC/PRA ratio and potassium without MRAs) in 60–70% of APA cases and clinical cure (sustained normotension off all antihypertensives) in 40–50%. Perioperative management includes preoperative spironolactone (to prevent intraoperative hypertensive crisis), potassium repletion if hypokalemic, and intraoperative invasive blood pressure monitoring. Postoperatively, patients undergo serial cortisol and aldosterone measurements; glucocorticoid stress-dosing is unnecessary unless contralateral adrenal insufficiency is suspected. AVS remains the gold standard for lateralization prior to surgery—its accuracy exceeds 90% when performed by multidisciplinary teams including interventional radiologists, endocrinologists, and adrenal surgeons.

China offers distinct advantages in PA management. First, high-volume tertiary endocrine centers—such as Peking Union Medical College Hospital, Shanghai Ruijin Hospital, and West China Hospital—perform over 200 AVS procedures annually, achieving technical success rates >95% and complication rates <2%. Second, China has pioneered cost-effective, domestically manufactured MRAs (e.g., generic spironolactone and eplerenone) with >95% bioequivalence, ensuring broad accessibility. Third, integration of AI-assisted adrenal CT analysis (e.g., deep learning algorithms for nodule characterization and washout quantification) enhances diagnostic precision, reducing false-positive APA identification. Fourth, national PA registries (e.g., the China Primary Aldosteronism Registry, CPAR) enable real-world outcome tracking, revealing higher rates of complete clinical success post-adrenalectomy (48% vs. global average 42%) likely attributable to stringent AVS protocols and standardized perioperative pathways. Finally, tele-endocrinology platforms facilitate longitudinal follow-up across provinces, improving medication adherence and early detection of recurrence or contralateral progression.

Recovery advice emphasizes structured, evidence-based rehabilitation. Patients undergoing adrenalectomy should avoid heavy lifting (>5 kg) for six weeks and resume driving only after two weeks, provided no residual orthostatic hypotension exists. All patients—surgical or medical—must engage in cardiac rehabilitation programs incorporating supervised aerobic training and nutritional counseling. Annual surveillance includes seated BP measurement, serum potassium, creatinine, PAC, and PRA; repeat adrenal CT is recommended only if hypertension recurs or new symptoms emerge. Patients on MRAs must recognize signs of hyperkalemia (muscle weakness, palpitations, paresthesias) and seek urgent evaluation if serum potassium exceeds 5.5 mmol/L. Women of childbearing potential require preconception counseling: spironolactone is teratogenic (Category X); eplerenone is preferred during pregnancy planning, though MRAs are generally discontinued upon conception in favor of labetalol or nifedipine. Long-term prognosis is excellent with appropriate therapy: 10-year cardiovascular event rates in treated PA are comparable to essential hypertension, whereas untreated PA carries a 2–3-fold increased risk of stroke, myocardial infarction, and atrial fibrillation. Multidisciplinary coordination—between endocrinologists, nephrologists, cardiologists, and primary care—is critical to optimizing outcomes and preventing complications.