title: Hyperkalemia in hospitalized patients treated with trimethoprim-sulfamethoxazole.
abstract: OBJECTIVE
  To determine the effect of standard-dose trimethoprim-sulfamethoxazole on serum potassium concentration in hospitalized patients.
  
  
  METHODS
  Prospective chart review.
  
  
  METHODS
  Community-based teaching hospital.
  
  
  METHODS
  105 patients with various infections were hospitalized and treated. Eighty patients treated with standard-dose trimethoprim-sulfamethoxazole (trimethoprim, < or = 320 mg/d; sulfamethoxazole, < or = 1600 mg/d) composed the treatment group; 25 patients treated with other antibiotic agents served as the control group.
  
  
  METHODS
  Serum sodium, potassium, and chloride concentrations; serum carbon dioxide content; anion gap; blood urea nitrogen level; and serum creatinine level.
  
  
  RESULTS
  The serum potassium concentration in the treatment group (mean +/- SD) was 3.89 +/- 0.46 mmol/L (95% CI, 3.79 to 3.99 mmol/L), and it increased by 1.21 mmol/L (CI, 1.09 to 1.32 mmol/L) 4.6 +/- 2.2 days after trimethoprim-sulfamethoxazole therapy was initiated. Blood urea nitrogen levels increased from 7.92 +/- 5.7 mmol/L (CI, 6.67 to 9.16 mmol/L) to 9.2 +/- 5.8 mmol/L (CI, 7.9 to 10.5 mmol/L), and serum creatinine levels increased from 102.5 +/- 49.5 mumol/L (CI, 91.4 to 113.6 mumol/L) to 126.1 +/- 70.7 mumol/L (CI, 110.3 to 141.9 mumol/L). Patients with a serum creatinine level of 106 mumol/L (1.2 mg/dL) or more developed a higher peak potassium concentration (5.37 +/- 0.59 mmol/L [CI, 5.15 to 5.59 mmol/L]) than patients with a serum creatinine level of less than 106 mumol/L (4.95 +/- 0.48 mmol/L [CI, 4.80 to 5.08 mmol/L]). Patients with diabetes had a slightly higher peak potassium concentration (5.14 +/- 0.45 mmol/L [CI, 4.93 to 5.39 mmol/L]) than did patients without diabetes (5.08 +/- 0.59 mmol/L [CI, 4.93 to 5.23 mmol/L]), but the difference was not statistically significant. The serum potassium concentration in the control group was 4.33 +/- 0.45 mmol/L (CI, 4.15 to 4.51 mmol/L), and it decreased nonsignificantly over 5 days of therapy.
  
  
  CONCLUSIONS
  Standard-dose trimethoprim-sulfamethoxazole therapy used to treat various infections leads to an increase in serum potassium concentration. A peak serum potassium concentration greater than 5.0 mmol/L developed in 62.5% of patients; severe hyperkalemia (peak serum potassium concentration > or = 5.5 mmol/L) occurred in 21.2% of patients. Patients treated with standard-dose trimethoprim-sulfamethoxazole should be monitored closely for the development of hyperkalemia, especially if they have concurrent renal insufficiency (serum creatinine level > or = 106 mumol/L).
authors.affiliation: Yale Primary Care Program, Department of Medicine, St. Mary's Hospital, Waterbury, CT 06706, USA.
authors.forename: R
authors.initials: R
authors.lastname: Alappan
authors.forename: M A
authors.initials: MA
authors.lastname: Perazella
authors.forename: G K
authors.initials: GK
authors.lastname: Buller
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000892:Anti-Infective Agents, Urinary / Q000009:adverse effects*; D001806:Blood Urea Nitrogen; D003404:Creatinine / Q000097:blood; D005260:Female; D006760:Hospitalization; D006801:Humans; D006947:Hyperkalemia / Q000139:chemically induced*; D007239:Infections / Q000097:blood / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000009:adverse effects*
chemical_list: D000892:Anti-Infective Agents, Urinary; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D003404:Creatinine