The Best Treatment Option to Pass a Uric Acid Kidney Stone

Kidney doctors work closely with urologists to help prevent and treat kidney stones. Not only does a patient want to pass troublesome stones, but they also want to avoid future kidney stones. If a patient suffers from a specific type of kidney stone called uric acid kidney stones, the best medical treatment we can offer the patient is a medication called potassium citrate.

Calcium oxalate stone is revealed and uric acid stone is revealed.

First, when a urologist makes a treatment decision whether a patient will get surgery or medical therapy for a sudden onset kidney stone, please appreciate that larger stones are harder to pass than smaller ones. If a stone is 6 millimeters or greater, the chance of spontaneous passage is 50 percent. If a stone is 10 millimeters or greater, the chance of spontaneous passage is almost zero and an intervention by a skilled urologist is important. Calcium stones are unique and the treatment of these stones may differ from the treatment of uric acid stones. Even though they look similar and they block tubes, the treatment options may differ. If you have a uric acid stone, it is possible to shrink the size of the stone by using a medication called potassium citrate. The citrate alkalinizes or lowers the amount of acid in the urine and shrinks the stone. Said another way, uric acid stones thrive in acid urine. If we change the composition of the urine, the uric acid stone is less likely to grow and may even shrink in size and pass into the urine. The dose of potassium citrate we usually prescribe is 40 to 80 milliequivalents total per day. We divide the total so the patient is taking the medication two or three times a day in order to keep the urine alkaline (not acidic). Once shrunk down, the stone can pass from the kidney down the ureter and into the bladder. As it continues to shrink, the uric acid stone will pass into the toilet.

Cartoon demonstrating the anatomy of the urinary system showing the connections from the kidney to the ureter to the bladder to the urethra.

The first and best step in the treatment of uric acid stones is urinary alkalinization. Other options include increasing the fluid intake so that a patient makes 2.5 liters of urine daily. In order to produce that much urine, you need to drink at least 2500 milliliters of water a day. The equivalent is 84 ounces or 10 cups of water. Another option that providers sometimes try is allopurinol. That medication decreases the uric acid level. Another medication that urologists sometimes try that is not as effective in this setting as potassium citrate is tamsulosin. The medication is safe and many specialists will recommend the use of tamsulosin. They may ask patients to take both tamsulosin and potassium citrate based on the size of the stone and the particular situation. Please remember that if the urologist determines the kidney stone is unlikely to pass, or potassium citrate is deemed to be ineffective, the patient may require a surgical intervention. We call one such surgical option lithotripsy.

Lithotripsy in action.

After the stone has passed, the kidney provider or urologist may suggest a metabolic workup to further analyze next steps regarding the evaluation and prevention of kidney stone disease. We commonly address the acute situation first: the stone that is causing a problem needs to be dealt with. Next, we focus on preventing future stones or ridding the body of stones that have already formed. If your urologist refers you to a kidney specialist, this metabolic workup and possible medication change is the expected plan. So if your provider suggests that you have uric acid stones, do not be surprised if we suggest potassium citrate as a therapy. Potassium citrate is extremely effective at shrinking uric acid stones.