Ask the Doctors Patient Care

Ask the Doctors: Kidney Stones

Alana Desai, MD

Kidney stones are exceptionally common and affect nearly one in ten Americans. Those who have suffered from stones understand that kidney stones can be incredibly painful when they begin to pass.

Washington University Urology offers advanced care for the treatment and prevention of kidney stones. In order to help the public know more about this condition, Alana Desai, MD, Assistant Professor of Surgery, answered frequently asked questions about kidney stones.

Kidney Stones: Frequently Asked Questions

What are kidney stones?

A kidney stone is a solid, pebble-like object made of minerals and salts, which can form in one or both of your kidneys when high levels of minerals are present in your urine. Kidney stones start small but can grow larger in sign, even filling the inner hollow structure of the kidney. Some stones stay in the kidney, are dissolved naturally by the organ and may not cause any problems. Sometimes, stones travel down the ureter, the tube between the kidney and the bladder. If the stone reaches the bladder, it can be passed out of the body in urine. If the stone becomes lodged in the ureter, it blocks the urine flow from that kidney and causes pain.

What causes kidney stones?

The most important contributing factor is dehydration, which is common among working adults. Potential stone-forming particles are typically dissolved in your urine. But, when you get dehydrated, your urine is not able to dissolve as many particles, and stone crystals can form. There are a number of other dietary factors. There can also be problems with your metabolism that may make you more likely to develop stones.

What do kidney stones feel like?

If you have a very small kidney stone that moves easily through your urinary tract, you may not have any symptoms, and may never know that you have a kidney stone.

If you have a larger kidney stone, you may notice symptoms like pain while urinating, blood in your urine, sharp pain in your back or lower abdomen, as well as nausea and vomiting.

Other signs of a kidney stone may include feelings of intense need to urinate and urinating more frequently, a fever and chills. Fever is often a sign of infection, and in combination with a kidney stone, can be potentially life threatening, requiring immediate evaluation and treatment. Generally, the larger the kidney stone, the more noticeable are the symptoms. Passing kidney stones can be quite painful, but the stones usually cause no permanent damage if they are recognized in a timely fashion

What are kidney stones made of?

The most common stones are made of calcium. Other compounds include struvite, which is associated with infections, and uric acid, which is the same material that produces gout attacks.

Can you prevent kidney stones?

Diets high in sodium can contribute to kidney stone disease. Keep in mind that fast foods, restaurant foods, canned foods, deli meats, even condiments such as soy sauce and ketchup contain high amounts of sodium and should be avoided or consumed in moderation. Additionally, you should talk to your doctor about your sodium intake and protein consumption as high amounts of protein and sodium can cause certain types of kidney stones.

You should avoid sugary drinks such as those containing sucrose or fructose. Water is the best fluid to drink.

How long does it take to pass a kidney stone?

With medical expulsive therapy, most small stones (less than 5 or 6 millimeters) will typically pass within a few days to a few weeks. Provided you are in good health, you can try for up to 6 weeks to pass a stone, although most patients elect for earlier intervention.

Can you force a kidney stone to pass?

To help smaller stones pass naturally, it is recommended you drink plenty of water, avoid fizzy drinks, and reduce your salt intake. Over-the-counter pain medications like acetaminophen, ibuprofen or naproxen can help relieve discomfort until the stones pass. Your doctor may also prescribe an alpha blocker which relaxes the muscles in your ureter and helps to pass the stone quicker and with less pain. This process may take a few days to a week or more.

If your stones are larger and are associated with more severe symptoms, you may require surgical treatment. 

How do you know if you have kidney stones?

Kidney stones can be diagnosed with tests and procedures ordered by your physician. These tests include blood tests to reveal any excess calcium or uric acid in your blood, urine testing to show if you are excreting too many stone-forming minerals or stone-preventing substances, and CT scans to reveal any stones in your urinary tract.

What can help with kidney stones?

If you have been diagnosed with a kidney stone and are waiting for it to pass naturally, it is important to drink plenty of water to prevent new stones from forming and move the stones through your urinary tract.

If your kidney stones are suspected to be caused by excessive calcium, you may add freshly squeezed lemon juice to your water. Lemons contain citrate, a chemical that prevents calcium stones from forming and assists in breaking up small stones to help them pass easier.

You may also take over-the-counter pain relievers like acetaminophen, ibuprofen or naproxen to help sooth your discomfort. 

Is cranberry juice good for kidney stones or is this a myth?

This is a common misconception shared by many people. There is little evidence to suggest that cranberry offers protection from urinary tract infections. But, more importantly, cranberry juices and extracts contain oxalates and are associated with a significant increase in the risk for kidney stones! So, if you are a stone former, you should avoid cranberry juice.

You should also avoid grapefruit juice. One glass of grapefruit juice can nearly double your risk of forming a stone.

Who can help me with kidney stones?

If you have been diagnosed with a kidney stone, call (314) 362-8200 to schedule an appointment with a Washington University urologist for evaluation and treatment. You may be directed to the emergency department for rapid evaluation if you are experiencing extreme pain, nausea, fever, or vomiting.

The stone experts at Washington University Urology also offer clinical consultations and treatments for kidney stones at Barnes-Jewish Hospital, Barnes-Jewish West County Hospital and Christian Hospital locations.