Empiric use of potassium citrate reduces kidney-stone incidence with the ketogenic diet

Pediatrics. 2009 Aug;124(2):e300-4. doi: 10.1542/peds.2009-0217. Epub 2009 Jul 13.


Objective: Kidney stones are an adverse event with the ketogenic diet (KD), occurring in approximately 6% of children who are started on this therapy for intractable epilepsy. Potassium citrate (Polycitra K) is a daily oral supplement that alkalinizes the urine and solubilizes urine calcium, theoretically reducing the risk for kidney stones.

Methods: Children who started the KD from 2000 to 2008 at Johns Hopkins Hospital, with at least 1 month of follow-up, were evaluated (N = 313). From 2000 to 2005, children were treated with daily Polycitra K at 2 mEq/kg per day only in the setting of identified hypercalciuria, whereas, since 2006, it has been started for all children empirically at KD onset.

Results: Polycitra K was administered to 198 children preventatively overall, 4 (2.0%) of whom developed kidney stones, compared with 11 (10.5%) of 105 who did not receive Polycitra K (P = .003). Two children since 2006 refused Polycitra K, 1 of whom developed a kidney stone. Successful empiric administration of Polycitra K at KD onset resulted in a kidney-stone incidence of 0.9% (1 of 106) compared with administration only because of hypercalciuria, 6.7% (13 of 195; P = .02). Polycitra K resulted in less acidic urine (mean pH: 6.8 vs 6.2; P = .002) but not reduced serum acidosis. No adverse effects of oral citrates were reported.

Conclusions: Oral potassium citrate is an effective preventive supplement against kidney stones in children who receive the KD, achieving its goal of urine alkalinization. Universal supplementation is warranted.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Baltimore
  • Child
  • Child, Preschool
  • Cohort Studies
  • Cross-Sectional Studies
  • Diet, Ketogenic / adverse effects*
  • Dietary Supplements*
  • Epilepsy / diet therapy*
  • Female
  • Follow-Up Studies
  • Hospitals, University
  • Humans
  • Incidence
  • Infant
  • Kidney Calculi / epidemiology
  • Kidney Calculi / etiology
  • Kidney Calculi / prevention & control*
  • Male
  • Potassium Citrate / administration & dosage*
  • Retrospective Studies


  • Potassium Citrate