Background: Salt sensitivity (SS) affects 50-60% of hypertensive patients and increases cardiovascular risk beyond blood pressure elevation alone. Mechanisms underlying individual variability in salt sensitivity remain incompletely understood.

Objective: To assess prevalence of salt sensitivity in essential hypertension patients, examine associated metabolic and renal factors, and evaluate blood pressure response to dietary sodium modification.

Methods: Prospective interventional study of 184 patients with untreated essential hypertension (mean age 54.7±8.9 years, 58% male) and 92 normotensive controls. Participants underwent standardized salt-loading (300 mmol/day sodium for 7 days) followed by salt-restriction (50 mmol/day for 7 days) protocols with 24-hour ambulatory blood pressure monitoring (ABPM). Salt sensitivity defined as mean arterial pressure (MAP) increase ≥5 mmHg from low-salt to high-salt diet. Plasma renin activity (PRA), aldosterone, urinary sodium excretion, and metabolic parameters were measured. Linear regression identified predictors of salt sensitivity magnitude.

Results: Among hypertensive patients, 106 (57.6%) were salt-sensitive (SS) versus 78 (42.4%) salt-resistant (SR). Controls showed 18.5% SS prevalence (p<0.001 vs. hypertensives). SS hypertensives demonstrated greater MAP increase during salt-loading (14.8±5.2 mmHg vs. 2.1±1.8 mmHg in SR, p<0.001) and larger decrease with restriction (12.6±4.8 mmHg vs. 2.4±1.6 mmHg, p<0.001). Baseline characteristics differing between SS and SR groups included: age (57.4±8.2 vs. 51.2±8.8 years, p<0.001), BMI (29.8±4.6 vs. 26.4±3.8 kg/m², p<0.001), fasting glucose (108.6±18.4 vs. 96.2±12.8 mg/dL, p<0.001), and insulin resistance (HOMA-IR: 4.2±2.1 vs. 2.4±1.2, p<0.001). SS patients showed suppressed PRA during high-salt (0.8±0.4 vs. 1.6±0.7 ng/mL/h in SR, p<0.001) and elevated aldosterone during low-salt (268±94 vs. 186±68 pg/mL, p<0.001). Urinary sodium excretion was paradoxically lower in SS patients during high-salt loading (242±68 vs. 284±52 mmol/24h, p=0.001), suggesting enhanced renal sodium retention. Multiple regression revealed independent predictors of SS magnitude: age (β=0.24, p=0.002), BMI (β=0.31, p<0.001), HOMA-IR (β=0.28, p=0.001), and baseline PRA (β=-0.22, p=0.006), explaining 48% of variance. African ancestry showed higher SS prevalence (72.3% vs. 51.2% in Europeans, p=0.008). During 6-month follow-up on low-sodium diet (<100 mmol/day), SS patients achieved greater BP reduction (-18.4/10.2 mmHg) than SR patients (-6.8/4.2 mmHg, p<0.001).

Conclusions: Salt sensitivity is prevalent in essential hypertension and strongly associates with obesity, insulin resistance, and renin-aldosterone dysregulation. Identifying SS individuals enables targeted dietary sodium restriction with enhanced therapeutic benefit. Findings support personalized approaches to hypertension management based on individual salt sensitivity status.

salt sensitivity, hypertension, dietary sodium, blood pressure, renin-angiotensin system, insulin resistance

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