Association of Antihypertensive Monotherapy With Serum Sodium and Potassium Levels in Chinese Patients

BACKGROUND International guidelines on management of hypertension recommend any major classes of antihypertensive drugs. However, the low prescribing rate of thiazides has been attributed to concerns about electrolyte disturbances and studies between anti hypertensive drug classes and hyponatremia/hypokalernia among Chinese patients were scarce. METHODS From clinical databases we included 2,759 patients who received their first-ever antihypertensive monotherapy from January 2004 to June 2007 in a large territory of Hong Kong.We studied the plasma sodium and potassium levels 8 weeks after prescriptions and factors associated with hyponatremia and hypokalemia by multivarriable regression analyses. RESULTS Among major anti hypertensive drug classes, thiazide users had the lowest sodium level (139.6 mEq/l, 95% confidence interval (CI) 139.3,140.0, P < 0.001) and patients-prescribed calcium channel blockers (CCBs; 3.92 mEq/l, 95% CI 3.89, 3.95) or thiazide diuretics (3.99 mEq/l, 95% CI 3,93,4.04) had the lowest potassium levels (P < 0.001). Multivariate analysis reported that advanced age (>= 70 years, odds ratio (OR) 7.49, 95% CI 2.84,19.8, P < 0.001), male gender (OR 2.38, 95% CI 1.45, 31.91, P < 0.001), and thiazide users (OR 2.42, 95% CI 1.29,4.56, P = 0.006) were significantly associated with hyponatremia, while renin-angiotensin system (RAS) (OR 0.31, 95% CI 0.13, 033, P = 0.008) and beta-blockers (BBs) (OR 0.35, 95% CI 0.23, 0.54, P < 0.001) users were less likely to present with hypokalemia. However, the proportions having normonatremic (95.1%) and normokalemic (89.4%) levels were high. CONCLUSIONS In view of the low prevalence of hyponatremia and hypokalemia associated with thiazides, physicians should not be deterred from prescribing thiazide diuretics as first-line