This study tests whether hydroxycitrate, a molecule closely related to citrate, can reduce calcium phosphate stone recurrence.
In this double-blind, placebo-controlled, randomized, crossover study, each participant will undergo 4 phases of study, with the order randomized by a blocked randomization scheme. The 4 phases will be Placebo, Super CitriMax (hydroxycitrate) OHCit low dose, OHCit standard dose, or Potassium Citrate. Randomization will be stratified based on sex, concomitant thiazide use, and concomitant alkali use. Each phase will be 1 week in duration, during which subjects will take assigned study medications. A minimum 1-week washout period will be imposed between phases. During the first 2 days of each phase, subjects will be instructed to adhere to a prescribed diet. On the last 5 days of each phase, subjects will be kept on a constant metabolic diet. Use of metabolic diet is essential to eliminate confounders that could occur from changes in dietary intake across phases. During the final two study days (days 6-7), two 24-hr urines will be collected for urine biochemistry and crystallization studies. Fasting blood will be obtained at the end of the last urine collection. Study Medications: Subjects will receive three tablets twice daily during each phase. These will consist of either placebo, Potassium Citrate (KCit), or Super CitriMax (OHCit). Study tablets will be prepared by a compounding pharmacy, with placebo tablets similar in appearance and size to the active medication tablets.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
QUADRUPLE
Enrollment
25
Hydroxycitrate Over-the-counter supplement, not FDA approved or regulated.
10 mEq Extended-release tablets for oral use
Placebo
UT Southwestern Medical Center
Dallas, Texas, United States
RECRUITINGFormation product (FP) for Calcium Phosphate
FP is obtained by adding increasing amounts of Calcium Chloride (CaCl2) to a series of urine aliquots maintained at constant pH for 2 hours, and is identified by the point at which calcium phosphate (CaP) precipitates as detected by an absorbance microplate reader. Calculated supersaturation using \[Calcium\] and \[Phosphate\] at that point represents FP.
Time frame: After 1 week of treatment
Crystal growth of Calcium Phosphate
We will assess crystal growth (CG) of CaP after seeding urine with a small amount of brushite (0.25 mg/ml urine) and incubating at 37°C for 3 hours (representing steady state) under constant stirring. A decrement in \[Calcium\]×\[Phosphate\] after seeding signifies crystal growth, while a \[Calcium\]×\[Phosphate\] increment represents crystal dissolution.
Time frame: After 1 week of treatment
Calcium Phosphate supersaturation
Supersaturation of calcium phosphate will be assessed by Joint Expert Speciation System (JESS).
Time frame: After 1 week of treatment
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
Hydroxycitrate Over-the-counter supplement, not FDA approved or regulated.