The incidence and prevalence of kidney stone disease has continually increased in both
developed and underdeveloped countries. With the surge in cases, the cost of treatment
has also increased substantially. In 2014, it has been reported that treatment of kidney
stones cost a total of 2.81 billion USD, and this is projected to increase by 1.24
billion USD per year. Although there has been great technological advancement in surgical
treatment of kidney stones, such as minimally invasive surgery, the rate of recurrence is
unfortunately high among stone formers, upwards of 50 percent at 5-10 years. Recurring
stone disease results in more frequent surgical interventions and further expense. Thus,
there is an increasing need for primary stone prevention.
Kidney stones have varying compositions with the most common being calcium oxalate. Uric
acid stones are the third most common type of stone and account for 10 percent of all
stone formers. One of the common abnormalities for patients with calcium oxalate stones,
is low citrate levels in the urine. Citrate is the primary inhibitor of calcium oxalate
crystal formation, growth, and aggregation. As such, regimens to increase urinary citrate
have been undertaken. The most common drug used in this regard is potassium citrate
(i.e., Urocit K). While effective, the drug remains costly with prescription costs
ranging as high as $450/month. With regard to uric acid stone formation, a prerequisite
is an acidic urine given that the pKa for uric acid is a pH of 5.5; once the pH is above
6.0, uric acid stones do not form. Indeed, the uric acid stone is the only one that can
be dissolved if one is able to raise the pH to 6.5 -7.0.
Current medical therapy for hypocitraturia in patients with calcium oxalate stones, is
the use of a slow-release tablet of potassium citrate (e.g., UrocitK). Current medical
therapy for uric acid stone formers is likewise potassium citrate as it will raise the
urine pH. A prescription of potassium citrate with the typical dosage of 30 meq twice a
day can cost the patient upwards of $450/month. Additionally, potassium citrate tablets
are associated with adverse effects such as nausea and diarrhea with additional concerns
with respect to the potassium load among patients with poor renal function. Furthermore,
the wax matrix tablets are large in size and difficult to swallow.
Pinheiro et al. in a prior study demonstrated that sodium bicarbonate in tablet form at a
dose of 60 milliequivalent (mEq) per day was comparable to Urocit-K in increasing urinary
pH and urinary citrate levels in calcium stone forming hypocitriuric patients. The study
was limited by a small sample size (n=16) and short duration of therapy (3 days). Despite
these favorable results, over the ensuing decade, there has been minimal interest in the
use of sodium bicarbonate as a preventative treatment in stone formers who are
hypocitriuric or uric acid stone formers.
Baking soda is a common household item and is openly available throughout the world in
most grocery stores. The main component of baking soda is sodium bicarbonate. Various
studies have shown that a teaspoon of baking soda (4.8g) has an equivalent of 59 mEq of
sodium bicarbonate. A pound of baking soda, or 96 teaspoons, costs $1 which reduces the
cost of a daily dosage of 60 mEq to less than a penny. The cost of 60 mEq (seven 650 mg
Pills) of Sodium Bicarbonate in pill form is 15 cents.
Investigators hypothesize that the use of baking soda in stone formers with calcium
oxalate associated hypocitraturia or with uric acid stones will increase urinary citrate
and increase urine pH to the benefit of both patient groups. If proven effective, this
approach could markedly lower the risk of stone formation in calcium oxalate and uric
acid stone formers, while providing an inexpensive solution on a global level to an
otherwise very expensive and debilitating ailment.
