Abstract
Background Salt sensitivity is associated with an increased cardiovascular risk, but the gold standard method (diet cycles) requires 24-h urine samples and has poor patient compliance. Objectives Test the hypothesis that oral fludrocortisone (0.4 mg per day for 7 days) is a good alternative in identifying salt-sensitive patients. Methodology We conducted a randomized crossover study with 30 hypertensive individuals comprising the following steps: (1) washout; (2) phase A (low- and high-sodium diet cycles); (3) washout 2; (4) phase B (fludrocortisone test). Phase A and B steps were performed in a random way. Consistent with the literature, we found that 53.3% were salt-sensitive according to the reference test. Using the ROC curve, the fludrocortisone test defined salt sensitivity by a median blood pressure increase of ≥3 mmHg. A good accuracy of fludrocortisone in detecting salt sensitivity was observed (AUC: 0.732±0.065; p<0.001), with 80% sensitivity and 53% specificity. Conclusion The fludrocortisone test is a good option for screening salt sensitivity in hypertensive patients. However, the low specificity prevents this test from being an ideal substitute to the labor-intensive diet cycles exam in the definition of salt sensitivity. This clinical trial is registered with NCT01453959.
Highlights
Salt sensitivity, defined by a significant blood pressure (BP) increase in response to salt consumption, is a potential major health problem
The current technique used for evaluating salt sensitivity comprises long diet cycles, good patient compliance with low- and highsodium intake, significant costs associated with the formulation of standardized meals, and two 24-h samples for urine sodium [12,13,14]
The mean sodium excretion, a measure of salt intake, during fludrocortisone administration was 187±84 mEq/vol During the fludrocortisone test stage, there was a significant reduction in renin, aldosterone, potassium, hemoglobin, and hematocrit on both the fourth and seventh days of administration, whereas sodium remained stable (Tables 2 and 3)
Summary
Salt sensitivity, defined by a significant blood pressure (BP) increase in response to salt consumption, is a potential major health problem. Previous studies revealed that approximately 51% of hypertensive and 26% of normotensive individuals are salt sensitive [5, 6] This condition is associated with target-organ damage [6,7,8,9], impaired glucose metabolism [10], and higher rate of fatal and nonfatal cardiovascular events [11]. We conducted a randomized crossover study with 30 hypertensive individuals comprising the following steps: (1) washout; (2) phase A (low- and high-sodium diet cycles); (3) washout 2; (4) phase B (fludrocortisone test). The low specificity prevents this test from being an ideal substitute to the labor-intensive diet cycles exam in the definition of salt sensitivity This clinical trial is registered with NCT01453959
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