Over-the-Counter Alkali Agents to Raise Urine pH and Citrate Excretion: A Prospective Crossover Study in Healthy Adults

Urology. 2022 Oct;168:72-78. doi: 10.1016/j.urology.2022.05.049. Epub 2022 Jul 16.


Objective: To assess the effect of 2 over-the-counter alkalizing agents on 24 hour urinary parameters.

Materials and methods: Ten healthy volunteers without a history of kidney stones were recruited to complete a baseline 24 hour urinalysis with a 4 day diet inventory. Participants then maintained the same diet on either LithoLyte (20 mEq 2 times per day) or KSPtabs (1 tablet 2 times per day) and submitted another 24 hour urinalysis. The process was repeated with the other supplement. Urinary alkali parameters were compared to baseline, and side effects were elicited with a questionnaire.

Results: LithoLyte intake resulted in a non-significant increase in citrate (597-758 mg/day, P =.058, an increase in urine pH (6.46-6.66, P =.028), and a decrease in urine ammonium (41-36 mmol/day, P =.005) compared to baseline. KSPtabs resulted in an increase in citrate (597-797 mg/day, P =.037) and urine pH (6.46-6.86, P =.037), with a non-significant decrease in ammonium (41-34 mmol/day, P =.059). No significant differences were seen comparing urinary analytes between LithoLyte and KSPtabs. With Litholyte, no side effects, mild, moderate, and severe side effects were seen in 50%, 40%, 10%, and 0%, respectively. With KSPtabs, rates were 60%, 20%, 10%, and 10%, respectively.

Conclusion: In healthy participants without a history of kidney stones, LithoLyte and KSPtabs are effective over-the-counter alkali supplements, with a similar side effect profile to prescription potassium citrate.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Alkalies
  • Ammonium Compounds*
  • Citrates
  • Citric Acid / adverse effects
  • Citric Acid / urine
  • Cross-Over Studies
  • Humans
  • Hydrogen-Ion Concentration
  • Kidney Calculi* / drug therapy
  • Potassium Citrate / therapeutic use
  • Prospective Studies


  • Potassium Citrate
  • Citric Acid
  • Citrates
  • Alkalies
  • Ammonium Compounds