title: Potassium citrate decreases urine calcium excretion in patients with hypocitraturic calcium oxalate nephrolithiasis.
abstract: Two previous studies (<10 patients each) have demonstrated that alkali therapy may reduce urine calcium excretion in patients with calcium oxalate nephrolithiasis. The hypothesized mechanisms are (1) a decrease in bone turnover due to systemic alkalinization by the medications; (2) binding of calcium by citrate in the gastrointestinal tract; (3) direct effects on TRPV5 activity in the distal tubule. We performed a retrospective review of patients on potassium citrate therapy to evaluate the effects of this medication on urinary calcium excretion. A retrospective review was performed of a metabolic stone database at a tertiary care academic hospital. Patients were identified with a history of calcium oxalate nephrolithiasis and hypocitraturia who were on potassium citrate therapy for a minimum of 3 months. 24-h urine composition was assessed prior to the initiation of potassium citrate therapy and after 3 months of therapy. Patients received 30-60 mEq potassium citrate by mouth daily. Inclusion criterion was a change in urine potassium of 20 mEq/day or greater, which suggests compliance with potassium citrate therapy. Paired t test was used to compare therapeutic effect. Twenty-two patients were evaluated. Mean age was 58.8 years (SD 14.0), mean BMI was 29.6 kg/m(2) (SD 5.9), and gender prevalence was 36.4% female:63.6% male. Mean pre-treatment 24-h urine values were as follows: citrate 280.0 mg/day, potassium 58.7 mEq/day, calcium 216.0 mg/day, pH 5.87. Potassium citrate therapy was associated with statistically significant changes in each of these parameters-citrate increased to 548.4 mg/day (p < 0.0001), potassium increased to 94.1 mEq/day (p < 0.0001), calcium decreased to 156.5 mg/day (p = 0.04), pH increased to 6.47 (p = 0.001). Urine sodium excretion was not different pre- and post-therapy (175 mEq/day pre-therapy versus 201 mEq/day post-therapy, p = NS). Urinary calcium excretion decreased by a mean of 60 mg/day on potassium citrate therapy-a nearly 30 % decrease in urine calcium excretion. These data lend support to the hypothesis that alkali therapy reduces urine calcium excretion.
authors.affiliation: Department of Urology, ShengJing Hospital of China, Medical University, Shenyang, 110004, Liaoning, People's Republic of China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Song
authors.affiliation: Department of Urology, Harvard Medical School, Massachusetts General Hospital, 55 Fruit Street, GRB 1102, Boston, MA, 02114, USA.
authors.forename: Natalia
authors.initials: N
authors.lastname: Hernandez
authors.affiliation: Department of Urology, Weill Cornell Medical College, New York Presbyterian Hospital, New York, NY, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Shoag
authors.affiliation: New York University Langone Medical Center Section of Nephrology, New York Harbor Veterans Affairs Healthcare System, New York, NY, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Goldfarb
authors.affiliation: Department of Urology, Harvard Medical School, Massachusetts General Hospital, 55 Fruit Street, GRB 1102, Boston, MA, 02114, USA. beisner@partners.org.
authors.forename: Brian H
authors.initials: BH
authors.lastname: Eisner
mesh_terms: D000328:Adult; D000368:Aged; D000863:Antacids / Q000008:administration & dosage / Q000627:therapeutic use*; D002118:Calcium / Q000652:urine*; D019343:Citric Acid / Q000652:urine*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D053040:Nephrolithiasis / Q000188:drug therapy* / Q000652:urine; D011188:Potassium / Q000652:urine; D019357:Potassium Citrate / Q000008:administration & dosage / Q000627:therapeutic use*; D012189:Retrospective Studies; D012964:Sodium / Q000652:urine; D062606:Tertiary Care Centers / Q000706:statistics & numerical data
chemical_list: D000863:Antacids; D019343:Citric Acid; D012964:Sodium; D019357:Potassium Citrate; D011188:Potassium; D002118:Calcium
keywords: Kidney stone; Potassium citrate; Urine calcium