Decoding Hyponatremia: A Systematic Review of Diagnostic Pathways and Therapeutic Approaches Applied When Correction Fails.

Hyponatremia is the most common electrolyte disorder encountered in clinical practice. Conventional management strategies, including fluid restriction, hypertonic saline, and solute supplementation, often fail to achieve sustained correction, particularly in the syndrome of inappropriate antidiuretic hormone secretion (SIADH), resulting in refractory cases. A systematic search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Eligible studies included randomized controlled trials, cohort studies, guideline syntheses, and mechanistic research, with risk of bias carefully evaluated. Seven studies met inclusion criteria. Tolvaptan consistently improved serum sodium concentrations in patients with SIADH and heart failure, though its use was limited by high cost and the potential for overly rapid correction. Oral urea emerged as a safe, inexpensive, and reliable option for gradual, sustained normalization of sodium levels. Vasopressin receptor antagonists (vaptans) demonstrated superiority over fluid restriction in oncology-associated hyponatremia, although relapse was frequently observed following discontinuation. Demeclocycline exhibited mechanistic efficacy but remains limited by nephrotoxicity risk. Guideline-based analyses emphasized improved diagnostic precision but revealed inconsistencies in correction thresholds and recommendations for second-line therapy. When standard correction measures fail, clinicians should reassess the underlying etiology and escalate treatment accordingly. Vaptans offer rapid correction, urea ensures safe long-term management, and demeclocycline serves as a last-line therapeutic option.