Kidney Stones: Symptoms, Causes, Treatment, and Prevention

Overview

Kidney stones, also known as renal calculi, are hard deposits made of minerals and salts that form inside your kidneys. They 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.

Kidney stones are a common condition, affecting about 1 in 11 people in the United States at some point in their lives, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Men are more likely to develop kidney stones than women, and the risk increases with age. Most kidney stones pass on their own, but some can cause severe pain and may require medical intervention.

Symptoms

Kidney stones may not cause symptoms until they move around within your kidney or pass into your ureter — the tube connecting the kidney and bladder. When this happens, you may experience:

• Severe pain in the side and back, below the ribs. This pain can radiate to the lower abdomen and groin. The pain often comes in waves and can fluctuate in intensity.
• Pain or burning sensation during urination.
• Pink, red, or brown urine, which indicates the presence of blood.
• Cloudy or foul-smelling urine, a sign of infection.
• Nausea and vomiting, often due to the severe pain.
• Persistent need to urinate, urinating more often than usual, or urinating in small amounts.
• Fever and chills, which may indicate an infection.

The pain caused by kidney stones has been described as one of the strongest pain sensations known. It often begins suddenly and can be debilitating.

Causes and Risk Factors

Kidney stones form when your urine contains more crystal-forming substances — such as calcium, oxalate, and uric acid — than the fluid in your urine can dilute. At the same time, your urine may lack substances that prevent crystals from sticking together, creating an ideal environment for kidney stones to form.

Types of Kidney Stones

Knowing the type of kidney stone you have helps determine its cause and may give clues on how to reduce your risk of getting more. Types include:

• Calcium stones: The most common type, usually in the form of calcium oxalate. Oxalate is a substance found in certain foods, such as nuts, chocolate, and some fruits and vegetables.
• Struvite stones: Form in response to a urinary tract infection. These stones can grow quickly and become quite large.
• Uric acid stones: 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.
• Cystine stones: Form in people with a hereditary disorder called cystinuria, which causes the kidneys to excrete too much of a specific amino acid.

Risk Factors

Several factors can increase your risk of developing kidney stones:

• Family or personal history: If someone in your family has had kidney stones, you're more likely to develop them. If you've already had one or more kidney stones, you're at increased risk of developing another.
• Dehydration: Not drinking enough water each day can increase your risk. People who live in warm climates and those who sweat a lot may be at higher risk than others.
• Certain diets: Eating a diet that's high in protein, sodium (salt), and sugar may increase your risk of some types of kidney stones.
• Obesity: High body mass index (BMI), large waist size, and weight gain have been linked to an increased risk of kidney stones.
• Digestive diseases and surgery: Gastric bypass surgery, inflammatory bowel disease, or chronic diarrhea can cause changes in the digestive process that affect your absorption of calcium and water, increasing the levels of stone-forming substances in your urine.
• Other medical conditions: Diseases and conditions that may increase your risk of kidney stones include renal tubular acidosis, cystinuria, hyperparathyroidism, and repeated urinary tract infections.
• Certain supplements and medications: Vitamin C, dietary supplements, laxatives (when used excessively), calcium-based antacids, and certain medications used to treat migraines or depression can increase your risk of kidney stones.

Diagnosis

If your doctor suspects you have a kidney stone, you may have diagnostic tests and procedures, such as:

• Blood tests: These can reveal too much calcium or uric acid in your blood, helping to monitor the health of your kidneys.
• Urine tests: A 24-hour urine collection test may show that you're excreting too many stone-forming minerals or too few stone-preventing substances.
• Imaging tests: Imaging tests may show kidney stones in your urinary tract. Options range from simple abdominal X-rays to high-speed or dual-energy computerized tomography (CT) scans.
• Analysis of passed stones: If you pass a kidney stone, your doctor may ask you to try to catch it by urinating through a strainer. Lab analysis will reveal the makeup of your kidney stone, which helps determine the cause and may give clues on how to reduce your risk of more stones.

According to the Mayo Clinic, imaging tests are crucial for confirming the diagnosis and determining the size and location of the kidney stone, which influences treatment decisions.

Treatment Options

Treatment for kidney stones varies, depending on the type of stone and the cause. Small stones with minimal symptoms may not require invasive treatment. You may be able to pass a small stone by:

• Drinking water. Drinking as much as 2 to 3 quarts (1.9 to 2.8 liters) a day may help flush out your urinary system.
• Pain relievers. Your doctor may recommend over-the-counter pain relievers to help with the discomfort.
• Medical therapy. Your doctor may give you a medication to help pass your kidney stone. This type of medication, known as an alpha blocker, relaxes the muscles in your ureter, helping you pass the kidney stone more quickly and with less pain.

Large Stones and Those That Cause Symptoms

Kidney stones that are too large to pass on their own or cause bleeding, kidney damage, or ongoing urinary tract infections may require more-extensive treatment. Procedures may include:

• Using sound waves to break up stones: Known as extracorporeal shock wave lithotripsy (ESWL), this procedure uses sound waves to create strong vibrations that break the stones into tiny pieces that can be passed in your urine.
• Surgery to remove very large stones: A procedure called percutaneous nephrolithotomy involves surgically removing a kidney stone using small telescopes and instruments inserted through a small incision in your back.
• Using a scope to remove stones: Your doctor may pass a thin tube (ureteroscope) equipped with a camera through your urethra and bladder to your ureter. Once the stone is located, special tools can snare the stone or break it into pieces that will pass in your urine.
• Parathyroid gland surgery: Some calcium phosphate stones are caused by overactive parathyroid glands, which are located on the four corners of your thyroid gland, just below your Adam's apple. When these glands produce too much parathyroid hormone, your calcium levels can become too high, leading to the formation of kidney stones.

Living with Kidney Stones

If you've had a kidney stone, you're at risk of developing another. To reduce this risk and manage your condition, consider the following tips:

• Stay hydrated: Drink enough fluids, mainly water, to produce at least 2.5 liters of urine a day. This helps flush away the substances that form stones.
• Eat fewer oxalate-rich foods: If you tend to form calcium oxalate stones, your doctor may recommend restricting foods rich in oxalates, such as rhubarb, beets, okra, spinach, Swiss chard, sweet potatoes, nuts, tea, chocolate, and soy products.
• Choose a diet low in salt and animal protein: Reduce the amount of salt you eat and choose non-animal protein sources, such as legumes.
• Continue eating calcium-rich foods: Calcium in food doesn't have an effect on your risk of kidney stones. Continue eating calcium-rich foods unless your doctor advises otherwise.
• Use medications with caution: Calcium-based antacids can increase your risk of forming stones. If you take other medications, ask your doctor if they increase your risk of kidney stones.

Regular follow-ups with your healthcare provider are essential to monitor your kidney health and adjust your prevention plan as needed.

Prevention

Preventing kidney stones means preventing the conditions that support their formation. Here are some strategies to help reduce your risk:

• Drink plenty of water: Aim for about 2.5 liters of urine output per day. This may mean drinking up to 3 liters of fluid daily, depending on your activity level and climate.
• Eat a balanced diet: Include a variety of fruits and vegetables, limit salt and animal protein, and ensure you're getting enough calcium from food sources.
• Maintain a healthy weight: Obesity is a risk factor for kidney stones. Work with your doctor to create a weight loss plan if needed.
• Limit sodium and sugar: High sodium intake increases the amount of calcium in your urine. Similarly, high sugar intake, especially from fructose, can increase your risk of kidney stones.
• Monitor your medication and supplement use: Some medications and supplements, like vitamin C and certain antacids, can increase your risk. Always consult your doctor before starting new medications or supplements.

According to the National Kidney Foundation, making these lifestyle changes can significantly reduce your risk of developing kidney stones.

Complications

Kidney stones don't always stay in the kidney. They can travel down the urinary tract, causing complications such as:

• Urinary tract infections: Stones can cause blockages that lead to infections.
• Kidney damage: If stones block the flow of urine out of both kidneys or if you have only one kidney, this can lead to kidney damage or even kidney failure.
• Recurrent stone formation: People who have had one kidney stone are at increased risk of developing another.
• Chronic kidney disease: Repeated bouts of kidney stones can contribute to the development of chronic kidney disease.

Early diagnosis and treatment can help prevent these complications. Regular monitoring and follow-up care are crucial for individuals with a history of kidney stones.

When to Seek Emergency Care