Elevated urinary sodium thresholds in high-salt diet heart failure: implications for diuretic resistance diagnosis

Background: Urinary sodium has been widely validated as a biomarker for diagnosing diuretic resistance (DR) in heart failure (HF) patients in Western populations; however, its role in DR Diagnosis and HF management remains unclear in high-sodium dietary regions such as northern China. Methods: In this single-center, prospective cohort study, from November 2021 to March 2024, 285 consecutive patients with acute decompensated HF (ADHF) received intravenous furosemide >80 mg/day. DR was defined as persistent fluid retention despite adequate diuretic dosing (>80 mg/day IV furosemide or equivalent), inadequate urine output (<0.5-1 mL/kg/h), or insufficient weight loss (<0.5-1 kg/day). Their urinary sodium concentrations at baseline, and at 1, 2, and 3-6 h post-administration of a 40 mg intravenous furosemide bolus were recorded. Results: In total, 177 patients were with DR and 108 non-DR. Both DR and non-DR groups exhibited markedly elevated 24-hour urinary sodium compared to western populations (130.3 in DR and 161.46 mmol/24 h in non-DR). ROC analysis indicated optimal thresholds of spot urinary sodium <85.8 mmol/L (AUC=0.791) and 1-hour post-dose urinary sodium <98.7 mmol/L (AUC=0.915) for diagnosing DR, outperforming traditional metrics. Low urinary sodium levels (spot <55.2 mmol/L, 1-hour <87.3 mmol/L) independently predicted all-cause mortality (AUC: 0.656 and 0.654, respectively). Conclusions: In high dietary sodium regions, urinary sodium thresholds for diagnosing DR are significantly higher than the western population, emphasizing the need for region-specific urinary sodium thresholds in such population.