title: Association of antihypertensive monotherapy with serum sodium and potassium levels in Chinese patients.
abstract: 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 antihypertensive drug classes and hyponatremia/hypokalemia 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 multivariable regression analyses.
  
  
  RESULTS
  Among major antihypertensive 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 (> or =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, 3.91, 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, 0.73, 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 antihypertensive agents as recommended by most international guidelines.
authors.affiliation: School of Public Health, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong SAR, The People's Republic of China.
authors.forename: Johnny Y
authors.initials: JY
authors.lastname: Jiang
authors.forename: Martin C S
authors.initials: MC
authors.lastname: Wong
authors.forename: Mohammed K
authors.initials: MK
authors.lastname: Ali
authors.forename: Sian M
authors.initials: SM
authors.lastname: Griffiths
authors.forename: Stewart W
authors.initials: SW
authors.lastname: Mercer
mesh_terms: D000367:Age Factors; D000368:Aged; D000959:Antihypertensive Agents / Q000009:adverse effects* / Q000145:classification / Q000627:therapeutic use; D002681:China / Q000453:epidemiology; D016208:Databases, Factual; D004305:Dose-Response Relationship, Drug; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000150:complications* / Q000188:drug therapy; D007008:Hypokalemia / Q000139:chemically induced / Q000453:epidemiology; D007010:Hyponatremia / Q000139:chemically induced / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000097:blood*; D012964:Sodium / Q000097:blood*; D016896:Treatment Outcome; D014883:Water-Electrolyte Imbalance / Q000139:chemically induced*
chemical_list: D000959:Antihypertensive Agents; D012964:Sodium; D011188:Potassium