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

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

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School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.



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.


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.


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.


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.

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