Kidney Stones: Types, Causes, Symptoms & Treatment 

Kidney stones (also called renal calculi, nephrolithiasis or urolithiasis) are hard deposits made of minerals and salts that form inside your kidneys.

Stone in your kidney simply means an irregularly-shaped solid mass or crystal that can be as small as a grain of sand up to the size of a golf ball. Depending on the size of your kidney stone (or stones), you may not even realize that you have one. Even small stones can cause extreme pain as they exit your body through your urinary tract. Drinking fluids may help the process, which can take as long as three weeks.

Diet, excess body weight, some medical conditions, and certain supplements and medications are among the many causes of kidney stones. Kidney stones can affect any part of your urinary tract — from your kidneys to your bladder. Often, stones form when the urine becomes concentrated, allowing minerals to crystallize and stick together.

When this happens, the stone can cause bleeding and keep urine from leaving your body. You may need surgery for a stone that can’t pass on its own.

Symptoms of kidney stones

Kidney stones can cause severe pain. Symptoms of kidney stones may not occur until the stone begins to move down the ureters. This severe pain is called renal colic. You may have pain on one side of your back or abdomen.

In men, pain may radiate to the groin area. The pain of renal colic comes and goes but can be intense. People with renal colic tend to be restless.

Other symptoms of kidney stones can include:

• blood in the urine (red, pink, or brown urine)
• vomiting
• nausea
• discolored or foul-smelling urine
• chills
• fever
• frequent need to urinate
• urinating small amounts of urine

In the case of a small kidney stone, you may not have any pain or symptoms as the stone passes through your urinary tract.

When to Seek immediate medical attention:

• Pain so severe that you can’t sit still or find a comfortable position
• Pain accompanied by nausea and vomiting
• Pain accompanied by fever and chills
• Blood in your urine
• Difficulty passing urine

Causes of kidney stones

Kidney stones are formed from substances in your urine. The substances that combine into stones normally pass through your urinary system. When they don’t, it’s because there isn’t enough urine volume, causing the substances to become highly concentrated and to crystalize. This is typically a result of not drinking enough water. The stone-forming substances are:

• Calcium.
• Oxalate.
• Uric acid.
• Phosphate.
• Cystine (rare).
• Xanthine (rare).

These and other chemicals are some of the waste products that exit your body.

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Types of kidney stones

Knowing the type of kidney stone you have will help determine its cause, and may give clues on how to reduce your risk of getting more kidney stones. If possible, try to save your kidney stone if you pass one so that you can bring it to your doctor for analysis.

Types of kidney stones include:

• Uric acid stones. Uric acid stones can form in people who lose too much fluid because of chronic diarrhea or malabsorption, those who eat a high-protein diet, and those with diabetes or metabolic syndrome. Certain genetic factors also may increase your risk of uric acid stones.
• Calcium stones. Most kidney stones are calcium stones, usually in the form of calcium oxalate. Oxalate is a substance made daily by your liver or absorbed from your diet. Certain fruits and vegetables, as well as nuts and chocolate, have high oxalate content. Dietary factors, high doses of vitamin D, intestinal bypass surgery and several metabolic disorders can increase the concentration of calcium or oxalate in urine. Calcium stones may also occur in the form of calcium phosphate. This type of stone is more common in metabolic conditions, such as renal tubular acidosis. It may also be associated with certain medications used to treat migraines or seizures, such as topiramate (Topamax, Trokendi XR, Qudexy XR).
• Struvite stones. Struvite stones form in response to a urinary tract infection. These stones can grow quickly and become quite large, sometimes with few symptoms or little warning.
• Cystine stones. These stones form in people with a hereditary disorder called cystinuria that causes the kidneys to excrete too much of a specific amino acid.

Risk factors of kidney stones

White men in their 30s and 40s are most likely to get kidney stones. However, anyone can develop kidney stones.

There are several risk factors for developing kidney stones. These include:

• Not drinking enough liquids.
• Having a diet that includes the substances that form the stones (phosphate, for example, is in meat, fish, beans and other protein-rich foods).
• Having a family history of kidney stones.
• Having a blockage in your urinary tract.

Some medications can increase your risk of developing a stone. These medications include:

• Diuretics (water pills).
• Calcium-based antacids (used to treat osteoporosis).
• Crixivan® (used to treat HIV infections).
• Topamax® and Dilantin® (used to treat seizures).
• Cipro® (ciprofloxacin, an antibiotic).
• Ceftriaxone (an antibiotic).

Certain foods can also place you at risk of a kidney stone. These foods include:

• Meats and poultry (animal proteins).
• Sodium (diets high in salt).
• Sugars (fructose, sucrose and corn syrup).

Certain medical conditions can also increase your risk of developing stones. This is because they may increase or decrease levels of the substances that make up a kidney stone. These conditions can include:

• Hypercalciuria (high calcium levels in your urine).
• High blood pressure.
• Diabetes.
• Obesity.
• Osteoporosis.
• Gout and cystic fibrosis.
• Kidney cysts.
• Parathyroid disease.
• Inflammatory bowel disease and chronic diarrhea.
• Some surgical procedures, including weight loss surgery or other stomach or intestine surgeries.

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Diagnosis of kidney stones

Diagnosis of kidney stones requires a complete health history assessment and a physical exam. Other tests include:

• blood tests for calcium, phosphorus, uric acid, and electrolytes
• blood urea nitrogen (BUN) and creatinine to assess kidney functioning
• urinalysis to check for crystals, bacteria, blood, and white cells
• examination of passed stones to determine their type

The following test can rule out obstruction:

• abdominal X-rays
• intravenous pyelogram (IVP)
• retrograde pyelogram
• ultrasound of the kidney (the preferred test)
• MRI scan of the abdomen and kidneys
• abdominal CT scan

The contrast dye used in the CT scan and the IVP can affect kidney function. However, in people with normal kidney function, this isn’t a concern.

There are some medications that can increase the potential for kidney damage in conjunction with the dye. Make sure your radiologist knows about any medications you’re taking.

Time to pass a kidney stone

The amount of time it can take for you to pass a kidney stone is different from another’s. A stone that’s smaller than 4 mm (millimeters) may pass within one to two weeks. A stone that’s larger than 4 mm could take about two to three weeks to completely pass.

Once the stone reaches the bladder, it typically passes within a few days, but may take longer, especially in an older man with a large prostate. However, pain may subside even if the stone is still in the ureter, so it’s important to follow up with your healthcare provider if you don’t pass the stone within four to six weeks.

Prevention of kidney stones

Prevention of kidney stones may include a combination of lifestyle changes and medications.

Lifestyle changes

You may reduce your risk of kidney stones if you:

• Drink water throughout the day. For people with a history of kidney stones, doctors usually recommend drinking enough fluids to pass about 2.1 quarts (2 liters) of urine a day. Your doctor may ask that you measure your urine output to make sure that you’re drinking enough water.If you live in a hot, dry climate or you exercise frequently, you may need to drink even more water to produce enough urine. If your urine is light and clear, you’re likely drinking enough water.
• Choose a diet low in salt and animal protein. Reduce the amount of salt you eat and choose nonanimal protein sources, such as legumes. Consider using a salt substitute, such as Mrs. Dash.
• Continue eating calcium-rich foods, but use caution with calcium supplements.Calcium in food doesn’t have an effect on your risk of kidney stones. Continue eating calcium-rich foods unless your doctor advises otherwise.Ask your doctor before taking calcium supplements, as these have been linked to increased risk of kidney stones. You may reduce the risk by taking supplements with meals. Diets low in calcium can increase kidney stone formation in some people.Ask your doctor for a referral to a dietitian who can help you develop an eating plan that reduces your risk of kidney stones.
• Eat fewer oxalate-rich foods. If you tend to form calcium oxalate stones, your doctor may recommend restricting foods rich in oxalates. These include rhubarb, beets, okra, spinach, Swiss chard, sweet potatoes, nuts, tea, chocolate, black pepper and soy products.

Medications to prevent kidney stones

Medications can control the amount of minerals and salts in the urine and may be helpful in people who form certain kinds of stones. The type of medication your doctor prescribes will depend on the kind of kidney stones you have. Here are some examples:

• Uric acid stones. Your doctor may prescribe allopurinol (Zyloprim, Aloprim) to reduce uric acid levels in your blood and urine and a medicine to keep your urine alkaline. In some cases, allopurinol and an alkalizing agent may dissolve the uric acid stones.
• Calcium stones. To help prevent calcium stones from forming, your doctor may prescribe a thiazide diuretic or a phosphate-containing preparation.
• Cystine stones. Along with suggesting a diet lower in salt and protein, your doctor may recommend that you drink more fluids so that you produce a lot more urine,. If that alone doesn’t help, your doctor may also prescribe a medication that increases the solubility of cystine in your urine.
• Struvite stones. To prevent struvite stones, your doctor may recommend strategies to keep your urine free of bacteria that cause infection, including drinking fluids to maintain good urine flow and frequent voiding. In rare cases long-term use of antibiotics in small or intermittent doses may help achieve this goal. For instance, your doctor may recommend an antibiotic before and for a while after surgery to treat your kidney stones.

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Treatment of kidney stones

Once diagnosed, your healthcare provider will first determine if you even need treatment. Some smaller kidney stones may leave your system when you urinate. This can be very painful. If your provider decides that you do need treatment, your options include medications and surgery.

Medications

Medications may be prescribed to:

• Decrease pain. Your healthcare provider may recommend that you take an over-the-counter medication like ibuprofen or, if you’re in the emergency room, an IV narcotic.
• Relax your ureter so that the stones pass. Commonly prescribed medicines include tamsulosin (Flomax®) and nifedipine (Adamant® or Procardia®).
• Manage nausea/vomiting. 

You should ask your healthcare provider before you take ibuprofen. This drug can increase the risk of kidney failure if taken while you’re having an acute attack of kidney stones — especially in those who have a history of kidney disease and associated illnesses such as diabetes, hypertension and obesity.

Surgery

There are four types of surgeries used to treat kidney stones. The first three are minimally invasive, meaning that the surgeon enters your body through a natural opening (like your urethra), or makes a small incision.

• Ureteroscopy: To perform this procedure, a small instrument called an ureteroscope is inserted in your urethra, through your bladder and into a ureter. This instrument shows the kidney stones and then retrieves them in a surgical “basket,” or breaks them apart using a laser. These smaller pieces of the kidney stones are then easily able to exit your body through your urinary tract.
• Shockwave lithotripsy: In this procedure, you’re placed on a special type of surgical table or tub. High-energy shockwaves are sent through water to the stone(s). The shockwaves break apart the stones, which are then more easily able to exit your body.
• Percutaneous nephrolithotomy: When kidney stones can’t be treated by the other procedures — either because there are too many stones, the stones are too large or heavy or because of their location — percutaneous nephrolithotomy is considered. In this procedure, a tube is inserted directly into your kidney through a small incision in your back. Stones are then disintegrated by an ultrasound probe and suctioned out so that you don’t have to pass any fragments. A urethral stent is placed after the procedure (an internal tube from the kidney to the bladder which is removed one week later). Patients are typically kept overnight for observation.
• Open stone surgery: A longer cut is used during this surgery. Compared to minimally invasive procedures, it’s rarely performed (0.3% to 0.7% of cases).

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