Primary Hyperaldosteronism: Epidemiology, Diagnosis, and Clinical Associations

Background/Objectives: Primary aldosteronism (PA), the leading cause of secondary hypertension, results from autonomous aldosterone hypersecretion. It is characterized by increased extracellular volume, elevated cardiac output, and greater arterial stiffness compared with essential hypertension, reflecting aldosterone-mediated hemodynamic dysregulation. The prevalence and morbidity of PA are increasingly acknowledged; however, PA continues to be underdiagnosed because of limited screening and diagnostic complexity. Methods: A narrative review was conducted using PubMed (2015–2025), with terms targeting PA epidemiology, excluding treatment-focused studies. From 971 articles, 133 relevant studies (original research studies, reviews, meta-analyses) were included, addressing prevalence, risk factors, comorbidities, genetics, and diagnostic issues. Results: PA prevalence in hypertensive populations is 5–10%, rising to 17.8% in young-onset and 20–30% in resistant hypertension. Screening indications include resistant/severe hypertension, hypokalemia, adrenal incidentaloma, young-onset disease, obstructive sleep apnea (59.8% comorbidity in hypertensive PA), and familial history, while a link may exist with papillary thyroid cancer. The aldosterone–renin ratio (ARR) is the primary screening tool, limited by assay variability and confounders (e.g., sodium intake). Confirmatory testing (such as with the saline infusion test) is often challenging to perform in routine practice. Adrenal venous sampling (AVS) is useful for subtyping unilateral (aldosterone-producing adenoma; APA; ~35–50%) vs. bilateral (idiopathic hyperaldosteronism; IHA) disease, despite technical challenges. Somatic mutations (e.g., KCNJ5, more frequent in Asians) and rare familial forms drive PA. Complications include cardiovascular events (Major Adverse Cardiovascular Events; MACE: 13.6% at 5.8 years), stroke, renal impairment (decreased eGFR, proteinuria), metabolic disorders (diabetes, obesity), and novel associations (vertebral fractures, renal stones, normal-tension glaucoma). Psychiatric comorbidities (depression/anxiety in 30–70% of patients) have been associated with central mineralocorticoid receptor effects, with sleep disturbances being prominent in females. Subclinical PA predicts hypertension and arterial stiffness. Conclusion: Improved screening protocols, standardized ARR cutoffs, and advanced imaging and genetic analyses are needed to enhance PA detection. Future research should validate cost-effective screening and clarify psychiatric-metabolic links for optimized management.