Overview

Renal calculi, commonly known as kidney stones, are hard deposits made of minerals and salts that form inside your kidneys. These 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.

Who Does It Affect?

Kidney stones can affect anyone, but certain groups are at higher risk:

• Men are more likely to develop kidney stones than women, with a lifetime risk of about 19% in men and 9% in women (NIH).
• Adults aged 20-50 are most commonly affected, though stones can occur at any age.
• People with a family or personal history of kidney stones.
• Individuals who are dehydrated or live in hot climates.
• Those with certain medical conditions, such as obesity, diabetes, or gout.

Prevalence

Kidney stones are a common medical problem. In the United States alone, kidney stones send more than 500,000 people to emergency rooms each year (Urology Care Foundation). The prevalence of kidney stones has been increasing worldwide, likely due to dietary factors and lifestyle changes.

Symptoms

Kidney stones often don’t cause symptoms until they move around within your kidney or pass into your ureter (the tube connecting the kidney and bladder). When this happens, the symptoms can be severe. Common symptoms include:

Primary Symptoms

• 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 fluctuates in intensity.
• Painful urination: A burning sensation or sharp pain when you urinate.
• Pink, red, or brown urine: This indicates the presence of blood in the urine (hematuria).
• Cloudy or foul-smelling urine: A sign of infection or the presence of minerals.
• Nausea and vomiting: Often accompany the severe pain.
• Persistent need to urinate: You may feel the urge to urinate more frequently than usual.
• Urinating small amounts: You might find yourself passing only small quantities of urine despite the urgency.
• Fever and chills: If an infection is present, you may experience fever and chills.

When Symptoms Require Immediate Attention

If you experience any of the following, seek medical help immediately:

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

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 spinach, nuts, and chocolate. Liver disease or dietary factors can increase oxalate levels in your urine.
• Struvite stones: Form in response to a urinary tract infection (UTI). These stones can grow quickly and become quite large.
• Uric acid stones: Form in people who lose too much fluid (dehydration), eat a high-protein diet, or have gout. Certain genetic factors also may increase your risk of uric acid stones.
• 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:

• Dehydration: Not drinking enough water is a major risk factor. People who live in warm climates and those who sweat a lot may be at higher risk.
• Diet: Eating a diet high in protein, sodium (salt), and sugar may increase your risk. High oxalate foods (like spinach, beets, and nuts) can also contribute.
• 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 such as renal tubular acidosis, cystinuria, hyperparathyroidism, and certain urinary tract infections can increase your risk.
• 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.

Diagnosis

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

Imaging Tests

• CT scan: A CT scan of your abdomen can reveal even tiny stones. This is the most common test for diagnosing kidney stones.
• Ultrasound: A non-invasive test that can help identify stones in the kidney or ureter. It’s often used for pregnant women or children to avoid radiation exposure.
• X-ray: An abdominal X-ray can miss small kidney stones but may be used to monitor the progress of treatment.

Lab Tests

• Urine testing: A 24-hour urine collection test may show that you're excreting too many stone-forming minerals or too few stone-preventing substances.
• Blood testing: Blood tests can reveal too much calcium or uric acid in your blood, which can lead to kidney stones.
• Analysis of passed stones: If you pass a stone, your doctor may ask you to collect it by urinating through a strainer. Lab analysis will reveal the makeup of your kidney stone, which helps determine the cause and can guide prevention strategies.

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:

Home Care

• Drinking water: Drinking as much as 2-3 liters (about 8-12 cups) of water a day may help flush out your urinary system. Unless your doctor tells you otherwise, drink enough fluid to produce clear or nearly clear urine.
• Pain relievers: Over-the-counter pain medications, such as ibuprofen (Advil, Motrin IB) or acetaminophen (Tylenol), can help relieve mild pain.
• 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 stone more quickly and with less pain.

Medical Procedures

If your stone is too large to pass on its own or causes bleeding, severe pain, or urinary tract infections, you may need more invasive treatment. Options include:

• 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. ESWL takes about 45-60 minutes and can cause moderate pain, so you may be under sedation or light anesthesia.
• Percutaneous Nephrolithotomy: This involves surgically removing a kidney stone using small telescopes and instruments inserted through a small incision in your back. You'll receive general anesthesia during the surgery and stay in the hospital for one to two days while you recover.
• Ureteroscopy: A thin tube (ureteroscope) equipped with a camera is passed 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 (hyperparathyroidism), your calcium levels can become too high, leading to kidney stones. Surgery to remove the growth from your gland stops the formation of kidney stones.

Living with Renal Calculi (Kidney Stones)

If you’ve had a kidney stone, you’re at risk of developing another. Here are some tips to help manage your condition and reduce the risk of recurrence:

Dietary Changes

• Stay hydrated: Drink plenty of water throughout the day. Aim for at least 2-3 liters daily unless your doctor advises otherwise.
• Reduce sodium: A high-sodium diet can increase calcium in your urine, raising your risk of stones. Limit processed foods, canned soups, and salty snacks.
• Limit animal protein: Eating too much animal protein (red meat, poultry, eggs, and seafood) can increase uric acid levels, leading to stones. Aim to limit your daily intake.
• Get enough calcium: Despite what you might think, getting too little calcium in your diet can increase your risk of kidney stones. Aim to get the recommended daily amount (1,000 mg for adults) from food or supplements.
• Avoid stone-forming foods: If you tend to form oxalate stones, limit foods rich in oxalates, such as spinach, rhubarb, nuts, and wheat bran.

Lifestyle Adjustments

• Maintain a healthy weight: Obesity can increase your risk of kidney stones. Work with your doctor to create a weight-loss plan if needed.
• Stay active: Regular physical activity can help prevent kidney stones by keeping your weight in check and reducing high blood pressure.
• Monitor your urine: Pay attention to the color and volume of your urine. Dark urine or urinating small amounts can be a sign of dehydration.

Medication Management

If you’re prone to certain types of stones, your doctor may prescribe medications to control the amount of minerals in your urine. For example:

• Thiazide diuretics to prevent calcium stones.
• Allopurinol to reduce uric acid levels.
• Antibiotics to treat struvite stones caused by infections.

Prevention

Preventing kidney stones means preventing the conditions that support their formation. Here are key strategies:

Hydration

Drinking plenty of water is the most important step in preventing kidney stones. Water dilutes the substances in urine that lead to stones. Strive to drink enough fluids to pass about 2.5 liters of urine a day. Include citrus beverages like lemonade and orange juice, which contain citrate that may prevent stone formation.

Dietary Recommendations

• Eat fewer oxalate-rich foods: If you tend to form calcium oxalate stones, restrict foods rich in oxalates. These include spinach, beets, okra, 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.

Medications

If you’re at high risk of recurring kidney stones, your doctor may recommend medications to control the levels of minerals and salts in your urine. The type of medication prescribed will depend on the type of kidney stones you have.

Regular Check-ups

If you’ve had kidney stones in the past, regular follow-ups with your doctor can help monitor your condition and adjust your prevention plan as needed. Your doctor may recommend periodic urine tests, blood tests, or imaging to check for new stone formation.

Complications

Kidney stones don’t usually cause permanent damage if recognized and treated promptly. However, complications can occur if stones are left untreated or if they recur frequently. Potential complications include:

Urinary Tract Infections (UTIs)

Stones can cause urinary tract infections by blocking the flow of urine, which allows bacteria to grow. UTIs can be serious if they spread to the kidneys or bloodstream.

Kidney Damage

Recurrent or large kidney stones can damage kidney tissue, leading to chronic kidney disease or kidney failure in severe cases.

Ureteral Obstruction

A stone lodged in the ureter can block the flow of urine, causing severe pain and potentially leading to kidney swelling (hydronephrosis) and damage.

Sepsis

In rare cases, an untreated urinary tract infection caused by a kidney stone can lead to sepsis, a life-threatening infection that spreads through the bloodstream.

Recurrence

People who have had one kidney stone are at increased risk of developing another. Without preventive measures, the recurrence rate can be as high as 50% within five years (NIH).

When to Seek Emergency Care

Conclusion

Kidney stones are a painful but treatable condition. By understanding the causes, recognizing the symptoms, and taking preventive measures, you can reduce your risk of developing stones or experiencing recurrences. If you suspect you have a kidney stone, consult your healthcare provider for a proper diagnosis and treatment plan. Early intervention can help you avoid complications and get back to your daily life quickly.

Additional Resources

• Mayo Clinic: Kidney Stones
• National Kidney Foundation: Kidney Stones
• Urology Care Foundation: Kidney Stones
• NIH: Kidney Stones