Kidney Stones: Causes, Symptoms, Treatment, and Prevention

21 October,2024

Kidney stones, aka nephrolithiasis, are a common painful condition affecting millions of people each year. If you've ever experienced them, you know how excruciating they can be. Despite their tiny size, they can cause immense discomfort and, if untreated, lead to serious complications. In this blog, we'll cover everything you need to know about kidney stones, from how they form and what causes them to prevention and treatment options. Our goal is to help you understand the issue in simple terms so you can take proactive steps to protect your health.

What are Kidney Stones?

Renal calculi, more commonly known as kidney stone, is a hard deposit of minerals in the kidneys. They can be as tiny as a salt granule or as large as a golf ball. While the stones may remain in the kidney unnoticed, they can travel through the urinary tract, causing severe pain, especially when they move through narrow tubes like the ureter (the tube that connects the kidney to the bladder).

Stones typically form when too much of certain minerals are in your urine. Uric acid and calcium oxalate are the most common composition of kidney stones, but other substances can also contribute. They tend to form when your urine becomes too concentrated—essentially when there isn't enough liquid to dissolve the substances. This results in the formation of crystals, which gradually grow into hard stones.

How are Kidney Stones Formed?

To understand how kidney stones are formed, it helps to know a little about how the kidneys work. Your kidneys act like filters for your blood, removing waste products and extra fluid to produce urine. When your kidneys filter blood, they also manage and regulate minerals like calcium, oxalate, phosphorus, and salts, which your body either uses or eliminates in urine.

Under normal conditions, your urine contains chemicals that prevent these minerals from clumping together. However, when the balance is off—due to dehydration, excess mineral content, or other factors—the minerals can begin to form crystals. These crystals stick together, forming a larger mass: the kidney stone.

Over time, the stone can grow in size. While some stones stay small enough to flow through the urinary tract unnoticed, bigger stones can cause significant pain and complications.

What are the Different Kinds of Kidney Stones?

Kidney stones can be differentiated based on the crystals they are made of. Not all kidney stones are similar, and knowing the type of stone helps reduce the risk of developing them in the future. The four major types of kidney stones are:

• Uric Acid Stones: These stones form when your urine is too acidic. Uric acid is a waste the body creates while breaking down purines—substances found in high amounts in certain meats, fish, and shellfish. Uric acid stones are more common in people with gout conditions or those with a high-protein diet.
• Calcium Stones: Calcium oxalate stones are one of the most common types of kidney stones. They form when the body's oxalate levels increase and combine with the calcium in the urine. Calcium phosphate stones are also possible in metabolic conditions such as renal acidosis. A diet high in calcium and low in oxalate can help you reduce your chances of developing calcium oxalate stones.
• Struvite Stones: These stones develop in response to an infection, especially urinary tract infections (UTIs). Bacteria responsible for these infections affect the pH balance of the urine, making it more alkaline. This environment allows struvite stones, composed of magnesium, ammonium, and phosphate, to form. Struvite stones can grow quickly and become large, sometimes causing serious kidney damage.
• Cystine Stones: This type of stone is the rarest and forms in people with a genetic disorder called cystinuria. It is a condition that causes the kidneys to excrete too much cystine, which clumps together and forms stones. People with cystinuria tend to develop recurrent stones starting in childhood or adolescence. It affects ~1 in 7,000 people globally. 

What Causes and Risk Factors of Kidney Stones?

A combination of dietary, genetic, and environmental factors can cause kidney stones. A few factors can increase your likelihood of developing kidney stones. Here are the most common reasons for kidney stones:

• Dehydration: Not drinking enough water is one of the leading causes of kidney stones. When dehydrated, your urine becomes more concentrated, making it easier for salts and minerals to crystallize and form stones.
• Diet: What you put inside your body plays a big role in stone formation. High sodium, protein, and oxalate levels in your diet can increase your risk of developing stones. A diet rich in animal protein, processed foods, and sugary drinks can also contribute to stone formation. For example, eating too much salt causes the kidneys to expel more calcium into the urine, which can lead to calcium stones.
• Obesity: Being obese or overweight significantly increases your risk of kidney stones. This is partly because obesity can lead to insulin resistance and changes in urinary pH, which create an environment conducive to stone formation.
• Medical Conditions: Certain medical conditions increase your risk of kidney stones. For instance, hyperparathyroidism can cause the body to produce too much calcium, forming calcium stones. People with gout are at higher risk for uric acid stones. Additionally, recurrent urinary tract infections can lead to struvite stones. People with inflammatory bowel diseases or who have undergone gastric bypass surgery are also at higher risk due to changes in how the body metabolizes minerals. 
• Family History: If someone in your family has had kidney stones, your chances of developing them increase. Genetics affects how your body processes minerals, particularly calcium and oxalates. Certain genetic conditions, like cystinuria, also predispose people to form stones.
• Certain Medications: Some medications and supplements can contribute to stone formation. For example, vitamin C, diuretics, topiramate (a medicine used to treat migraines or seizures), antibiotics, and calcium-containing antacids can increase your risk.

How Common are Kidney Stones?

Due to dietary habits, kidney stones are becoming increasingly common in urban populations. Men are at a higher risk of developing kidney stones than women. There were over 115 million worldwide cases of kidney stones in 2019. The diseases affect around 12% of the global population at some point in life. Kidney stones are responsible for over 500,000 emergency visits each year. The risk of the disease recurring is 10–23% per year, 50% within 5–10 years, and 75% within 20 years. 

What are the First Signs of Kidney Stones?

Kidney stones generally don't show signs until they start moving around within the kidney or pass into the ureter. The kidney stone symptoms depend on the location and size of the stone, but there are some common signs to watch out for:

• Severe Pain: The most common and noticeable symptom is intense pain in your back or side, typically just below the rib cage. The pain often radiates to the groin and lower abdomen as the stone flows through the urinary tract. The kidney stone pain can come in waves and fluctuate in intensity.
• Pain During Urination: If the stone moves into the ureter or reaches the bladder, you may feel sharp, stinging pain when you urinate.
• Blood in the Urine: Stones can irritate the urinary tract, causing the lining to bleed. As a result, your urine may appear pink, red, or brown.
• Nausea and Vomiting: The severe pain caused by kidney stones can lead to nausea and even vomiting.
• Frequent Need to Urinate: You may need to urinate more often but only pass small amounts of urine. This indicates that the stone may have moved into your bladder or urethra.
• Cloudy and Foul-smelling Urine: Kidney stones can sometimes lead to urinary tract infections (UTIs), which may cause your urine to appear cloudy or have a strong odor.

How are Kidney Stones Detected?

If you suspect you have a kidney stone, your doctor will perform a combination of diagnostic tests. These tests confirm the diagnosis and determine the location and size of the stone. Common methods of detecting kidney stones include:

1. Urine Tests: A 24-hour urine test can help determine whether your urine contains high levels of minerals that can form stones. This test is especially useful for identifying underlying issues that may be causing recurrent stones.
2. Blood Tests: Blood tests can reveal whether you have too much calcium or uric acid in your body, which could contribute to the formation of kidney stones. Blood tests also measure phosphorus, blood urea nitrogen (BUN), electrolytes, and creatinine levels to assess kidney functioning.
3. Imaging Tests:
   • CT Scans: A computed tomography (CT) scan is the most commonly used and accurate test for diagnosing kidney stones. It can detect the size, shape, and location of the stone.
   • Ultrasound: A noninvasive option is an ultrasound, which can also provide information about the size and location of the stone.
   • X-rays: In some cases, a simple X-ray of the abdomen may be used to locate certain types of stones, but it's not as reliable as a CT scan. Doctors order a KUB x-ray (kidney-ureter-bladder x-ray) to check if shock wave therapy is a kidney stone treatment option for you. An intravenous pyelogram (IVP) is also an option for diagnosing kidney stones. It is a special type of urinary system X-ray taken after injecting a dye.

What Happens if You Don't Get Kidney Stones Treated?

A common question among patients is whether their condition is serious. Are kidney stones dangerous? Well, here is the answer. Most kidney stones tend to pass on their own within three weeks and aren't usually life-threatening. You won't even notice smaller stones as they are mostly symptomless. However, bigger stones can become dangerous if not treated on time. Ignoring such stones can lead to serious complications. Here are the risks of leaving kidney stones untreated:

• Infections: If a stone blocks urine flow, it can create a bacteria buildup in the urinary tract, leading to infections. In a few cases, these infections can pass to the bloodstream, a condition known as sepsis, which is life-threatening.
• Kidney Damage: Stones that block the urinary tract for a prolonged period damage the kidneys. In severe cases, this results in kidney failure, especially if both kidneys are affected.
• Recurrent Stones: Once you've had a renal calculi, there is a 50% chance of developing another within 5 to 7 years if the underlying cause isn't addressed. Recurrent stones can lead to chronic kidney damage over time. 
• Urinary Retention: A large stone can block the urethra, making urinating difficult or impossible. This requires immediate medical attention to prevent damage to the bladder and kidneys.

What are the Treatment Options for Kidney Stones?

Kidney stone treatment depends on the size, type, and location of the stone, as well as your overall health. Generally, there are 4 methods for kidney stone removal. These include extracorporeal shock wave lithotripsy, ureteroscopy, percutaneous nephrolithotomy, and medicines. The treatment options are mentioned below based on the size of the kidney stones. 

Small Stones

80% of kidney stones usually get removed from the body without any treatment. However, small stones may still require some medications and dietary changes. These include.

• Drink Plenty of Water: If your stone is small (typically under 5mm), your doctor may recommend drinking lots of fluids to help flush it out of your system. Aim to drink at least 1.8-3.2 liters of water daily to encourage the stone to pass.
• Pain Relief: Over-the-counter kidney stone pain relievers like ibuprofen or acetaminophen help manage the discomfort while you wait for the stone to pass.
• Medical Expulsion Therapy: Sometimes, your doctor may prescribe kidney stone medicines, like alpha-blockers (tamsulosin), to relax the muscles in your ureter and help the stone pass more easily.

Larger Stones

If the stone is too large to pass on its own or is causing severe pain or complications, medical intervention may be needed.

• Extracorporeal Shock Wave Lithotripsy (ESWL): This noninvasive procedure uses shock waves to crack the stone into tiny pieces, which can then pass more easily in the urine.
• Ureteroscopy: The doctor passes a thin, flexible tube called a ureteroscope through the urethra to reach the stone. Using a laser, the doctor can remove or break the stone into smaller pieces.
• Percutaneous Nephrolithotomy (PCNL): Surgery may be required for large stones. PCNL involves making a small incision in the back to remove kidney stones.
• Parathyroid Surgery: Hyperthyroidism is a risk factor for kidney stones. It is a condition in which the parathyroid glands produce high levels of parathyroid hormone, which also increases the level of calcium. Treating conditions responsible for hyperthyroidism is necessary to remove kidney stones and prevent reoccurrence. 

Medication for Kidney Stones

Certain medications help manage kidney stones effectively. Doctors prescribe different kidney stone medicines depending on your type of stone. 

• Calcium Stones: For calcium stones, a thiazide diuretic or a phosphate-containing preparation may help reduce calcium levels in your urine.
• Uric Acid Stones: If you have uric acid stones, your doctor may prescribe allopurinol to lower the acid levels in your blood and urine. They may also prescribe an alkalizing agent (sodium bicarbonate) to keep your urine alkaline.
• Struvite Stones: Doctors recommend keeping urine free of infection-causing bacteria to treat struvite stones. You can achieve this by drinking fluids to maintain good urine flow and frequent voiding. In severe cases, antibiotics in small or intermittent doses may help achieve this goal. 
• Cystine Stones: In addition to suggesting a diet lower in salt and protein, your doctor may prescribe kidney stone medicines (potassium citrate, acetazolamide) that increase the solubility of cystine in your urine.

Can Kidney Stones Pass on Their Own?

Yes, small kidney stones (under 5mm) can often pass on their own within 1-2 weeks, though the process can be painful. Staying hydrated by drinking plenty of liquids helps the stone move through the urinary tract more quickly. In some cases, physicians may prescribe medicines to help relax the ureter and make passing the stone easier.

However, larger stones (greater than 5mm) are less likely to pass on their own and may require medical intervention. Stones larger than 10mm almost always need to be removed surgically or through other procedures like shock wave therapy.

Stones that move out of the body without requiring surgical intervention have a four-stage process. These stages are decided based on the location at which the stone is present.

• Stage 1: After a kidney stone forms, you may feel spasms as your kidneys try to push out the stone. This can cause severe back pain.
• Stage 2: During this stage, the stone moves into the ureter, the tube connecting the bladder and kidneys. Depending on the stone size, this stage can also cause pain and feeling of intense pressure.
• Stage 3: Most pain will subside once the stone reaches the bladder. However, you may feel an increased pressure in the bladder and a need to urinate more often.
• Stage 4: The final stage is when the stone reaches the urethra. During this stage, you need to push extra to pass the stone with the urine through the opening of the urethra. Most people can notice kidney stones in the toilet when they move out of the body. 

What Size of Kidney Stones Requires Surgery?

As discussed earlier, surgery is typically recommended when a kidney stone is larger than 10 mm and shows no signs of passing independently. Such stones may cause significant pain, blockages, or infections.

Kidney stones within the 5–8 mm size range, especially in the distal ureter, often pass with medical expulsive therapy (MET).

Doctors usually recommend a "wait-and-see" approach with increased fluid intake and pain management for stones under 5 mm. Further treatment may be necessary if the stone does not pass within a time period.

How to Prevent Kidney Stones?

Prevention is often the best treatment for not just kidney stones but for most diseases. Making simple lifestyle changes can remarkably reduce your risk of developing stones:

• Stay Hydrated: Drinking enough water is one of the most vital steps to prevent kidney stones. Aim for at least 2-3 liters of water per day. Staying hydrated helps dilute the substances in your urine that can form stones.
• Eat a Balanced Diet: Focus on a diet rich in fruits, vegetables, and whole grains. Limit foods that are high in oxalates, sodium, and animal proteins. Adding foods high in citrate (such as lemons and oranges) can help prevent stones from forming.
• Limit Sodium: Reducing your salt intake can help lower the amount of calcium in your urine. Aim at consuming less than 2,300 mg of sodium per day.
• Have Enough Calcium: While it is true that calcium and oxalates are responsible for most kidney stones, having a natural diet rich in calcium can help you prevent these stones, as calcium binds with oxalate before it reaches the kidneys. However, the same isn't true for calcium supplements, as they increase your risk for stones.
• Stay Active: Regular physical activity helps regulate your weight and improve kidney function, reducing your risk of stones.
• Monitor Medications: If you're taking medications that could contribute to kidney stone formation, consult your doctor. They may recommend adjustments to your medication or suggest alternative treatments to reduce your risk.
• Treat Underlying Conditions: Patients with a disorder that increases the risk of kidney stones should work with their doctors to manage the condition and reduce the likelihood of stones forming.

Food Items to Avoid if You Have Kidney Stones

Diet has a significant role in the development of kidney stones. If you've had kidney stones before or are at risk of developing them, it's important to avoid certain foods that can contribute to stone formation:

• Oxalate-rich Foods: Oxalates are compounds found in many foods that can bind with calcium to form kidney stones. Foods high in oxalates include nuts, chocolate, spinach, beets, and tea. Reducing the intake of such foods can help prevent calcium oxalate stones.
• High-sodium Foods: Too much sodium in your diet can cause your kidneys to excrete more amount of calcium into your urine, increasing the risk of stones. Avoid processed foods, canned soups, salted snacks, and fast foods.
• Sugary Drinks: Drinks that are high in sugar, especially sodas and energy drinks, can increase the risk of kidney stones. Cold drinks have a high amount of phosphates, a compound linked with kidney stone formation.
• Animal Protein: High-protein diets, especially those rich in red meat, poultry, and seafood, can increase uric acid levels in the body, leading to uric acid stones.
• Calcium Supplements: Low levels of calcium cause elevation in the body's oxalates level. This increases the risk of calcium oxalate stones. While calcium from natural sources is generally safe, taking high doses of calcium supplements can further increase your risk of kidney stones. If you take calcium supplements, be sure to consult with your treating doctor for the appropriate dosage.

Key Takeaway

Kidney stones may be small, but their impact on your health can be significant. Understanding what causes kidney stones, recognizing the symptoms, and knowing treatment options can help you manage the condition and avoid future stones. The best way to prevent kidney stones is to stay hydrated, eat a balanced diet, and address any underlying health issues.

If you experience symptoms of kidney stones, such as blood in the urine or severe pain, seek medical attention promptly. Early intervention can prevent complications and reduce your discomfort. With small lifestyle changes, you can reduce the risk of kidney stones and keep your kidneys healthy for the long term.