Increased sodium intake correlates with greater use of antihypertensive agents by subjects with chronic kidney disease

Background: Hypertension is a common disease in patients with chronic kidney disease (CKD) and predisposes to heart disease, stroke, and progression of renal failure. In the general population, sodium restriction has been shown to improve blood pressure (BP) control, but this is not widely recommended in CKD patients. The aim of this study was to assess the sodium balance in a CKD clinic and its effect on BP management. Methods: We retrospectively reviewed charts from June 1998 through to June 2003 and included all patients with an estimated glomerular filtration rate (GFR) of < 30 mL/min who completed a 24-h urine collection for sodium. Patients were divided into tertiles based upon their 24-h sodium excretion and analyzed by ANOVA. Results: We included 141 CKD patients who had a mean (+/- SE) sodium excretion of 145.7 +/- 4.7 mmol/day. There were a significantly greater number of antihypertensive agents used with increasing sodium excretion (2.00 0.16, 2.61 +/- 0.20, and 2.77 +/- 0.19 medications, respectively for each fertile; P = .01). This difference was even more prominent when only those patients with a GFR <= 15 mL/min (n = 77) were examined (1.69 +/- 0.19, 2.52 +/- 0.27, and 3.08 +/- 0.26 medications, respectively; P = .001). Control of BP was equivalent in all groups. Multivariable analysis revealed sodium excretion (P = .00005) and age (P = .007) to be significantly associated with use of antihypertensive medication. Conclusions: We have demonstrated that increased sodium intake is associated with an increased number of antihypertensive medications to achieve comparable BP control in a population with CKD.