Kidney Stones – Causes, Symptoms, Treatments

What are Kidney Stones?

Kidney stones are hard deposits that form in the kidneys. They are made of minerals and salts that are normally found in urine. When these substances become too concentrated, they can crystallize and form stones.

Globally, the prevalence of kidney stones appears to be on the rise.  Studies estimate that about one in ten people will develop a kidney stone during their lifetime according to the National Kidney Foundation. That translates to millions of people experiencing this painful condition each year in the United States alone. Men are more likely to develop kidney stones than women, with a prevalence of around 11% compared to 6%.

This trend is likely due to a combination of factors, including:

• Dietary Changes: Increased consumption of processed foods high in sodium, animal protein, and sugar might be contributing factors.
• Decreased Fluid Intake: Busy lifestyles and sugary beverages replacing water could be leading to dehydration, a major risk factor.
• Obesity Rates: The rise in obesity rates globally is another potential contributor.
• Improved Diagnostic Techniques: Advancements in medical imaging might also be playing a role, leading to the detection of more kidney stones that previously might have gone unnoticed.

Types of Kidney Stones

There are four main types of kidney stones, each with slightly different causes and compositions.

1. Calcium Oxalate Stones: These are the most common culprits, accounting for roughly 75-80% of all kidney stones. They form when calcium combines with oxalate, a substance found in certain foods (spinach, rhubarb, nuts) and even produced by the body. High levels of calcium or oxalate in the urine, or dehydration, can contribute to their development.
2. Uric Acid Stones: These form when uric acid, a waste product from the breakdown of purines (found in meat, seafood), builds up in the urine. Conditions like gout, a high-protein diet, or certain medications can increase uric acid levels and promote stone formation.
3. Struvite Stones: These are less common, arising from infections in the urinary tract. Bacteria that break down urea (another waste product) can release ammonia, leading to the formation of struvite stones.
4. Cystine Stones: The rarest of the bunch, cystine stones form due to a genetic disorder called cystinuria. This condition causes the excessive excretion of cystine, an amino acid, in the urine, leading to stone formation.

The development of kidney stones is a gradual process. Tiny crystals can form initially, and over time, they clump together and grow into larger stones. The size of kidney stones can vary greatly, ranging from a mere grain of sand to a large staghorn calculus, which resembles the antlers of a stag and fills the renal pelvis (the funnel-shaped area within the kidney that collects urine).

Shape also plays a role. While some stones may be smooth, others can be jagged or irregular.  This variation depends on the specific mineral composition and the pattern of crystal growth within the stone.

Texture-wise, kidney stones are generally hard and rough. However, struvite stones, due to their association with infection, can sometimes be softer and more crumbly.

Symptoms of Kidney Stones

Kidney stones often do not cause any impact until they move around within the urinary tract, causing a variety of uncomfortable and sometimes excruciating symptoms. Here’s a breakdown of the common signs you might experience:

Pain: This is the most prominent symptom and can be quite severe. The pain typically originates in the flank (the area on either side of your lower back, just below the ribs) and may radiate to the lower abdomen or groin. The intensity of the pain can fluctuate, often described as waves of sharp, cramping pain that can come and go.

Urinary Issues: Several issues with urination can indicate a kidney stone. You might experience a frequent urge to urinate, even if you only pass small amounts. Pain or burning sensation during urination can also occur. The urine itself might appear cloudy or bloody due to the presence of red blood cells released by irritation from the stone.

Nausea and Vomiting: The intense pain associated with kidney stones can often trigger nausea and vomiting. This can be a debilitating combination, adding to the overall discomfort.

Other Symptoms: Sometimes, additional symptoms like fever and chills might be present if an infection accompanies the kidney stone. Feeling restless and unable to find a comfortable position due to the pain are also common.

Causes of Kidney Stones

Several factors can contribute to the unwelcome formation of kidney stones. 

Inadequate fluid intake is a major risk factor. When you don’t drink enough fluids, your urine becomes more concentrated, creating an environment for minerals and salts to crystallize and form stones.

Certain dietary choices can influence kidney stone formation. Excessive salt intake can increase calcium excretion in the urine, promoting calcium oxalate stones. Diets rich in animal protein can increase uric acid levels, contributing to uric acid stones.

Vegetables high in oxalate, like spinach, rhubarb, and beets, can increase oxalate levels in some individuals, especially those prone to calcium oxalate stones. However, completely restricting these vegetables might not be necessary and can be discussed with a healthcare professional.

Sugary beverages, including sodas and fruit juices, have been linked to an increased risk of kidney stones, possibly due to their impact on metabolism and urine composition.

Certain medical conditions can predispose individuals to kidney stones. 

• Urinary tract infections (UTIs): Chronic UTIs can increase the risk of struvite stones.
• Gout: This condition, characterized by high uric acid levels, increases the risk of uric acid stones.
• Hyperparathyroidism: An overactive parathyroid gland can lead to high calcium levels in the blood and urine, promoting calcium stones.
• Cystinuria: This genetic disorder causes excessive cystine excretion in the urine, leading to cystine stones.

Certain medications, like diuretics and some weight-loss supplements, can alter urine composition and increase the risk of stone formation. Having a family member with kidney stones increases your own risk, suggesting a possible genetic predisposition in some cases.

Obesity is a risk factor for kidney stones, possibly due to changes in metabolism and urine composition. Additionally, some types of weight-loss surgery can increase the risk of kidney stones, particularly in the initial stages post-surgery.

Complications and Recurrence of Kidney Stones

While kidney stones themselves can be quite painful, the potential complications are what necessitate seeking medical attention.

• Pain and Discomfort: The main symptom of kidney stones is severe pain in the flank or lower abdomen that can radiate to the groin. This pain can be excruciating and debilitating, significantly impacting daily life.
• Urinary Tract Blockage: Kidney stones can lodge themselves in the ureter (the tube that carries urine from the kidney to the bladder), blocking the flow of urine. This blockage can cause pain, back up of urine in the kidney (potentially leading to damage), and increase the risk of infection.
• Infection: A blocked ureter due to a kidney stone can increase the risk of a urinary tract infection (UTI) as urine backs up and creates a breeding ground for bacteria. If left untreated, a UTI can progress to a kidney infection, which is a serious condition requiring prompt medical attention.
• Kidney Damage: Chronic or recurrent kidney stones can damage the kidneys over time.  If stones frequently block the flow of urine, it can lead to scarring and loss of kidney function. In severe cases, kidney failure might occur.
• Recurrence: Unfortunately, people who have had a kidney stone are more likely to experience them again. Studies suggest that the risk of recurrence can be as high as 50% within 10 years of the first episode.

Preventative Measures for Kidney Stones

Hydration is the cornerstone of kidney stone prevention. Aim for sufficient fluid intake throughout the day to dilute your urine and prevent mineral and salt concentration. Generally, healthcare professionals recommend 2-3 liters (around 8 glasses) of fluids daily.  However, this can vary depending on factors like climate, activity level, and overall health. Monitor your urine color – pale yellow is ideal, indicating adequate hydration.

While completely eliminating certain foods might not be necessary, some dietary modifications can be helpful:

• Reduce Sodium Intake: Excessive salt consumption can contribute to calcium excretion. Opt for a low-sodium diet and be mindful of hidden sodium in processed foods.
• Moderate Animal Protein: While protein is an essential nutrient, very high protein diets may increase uric acid levels and the risk of uric acid stones.
• Be Mindful of Certain Vegetables: If you’re prone to calcium oxalate stones, be moderate with oxalate-rich vegetables like spinach, rhubarb, and beets. However, consult a healthcare professional or registered dietitian for personalized advice, as completely restricting these vegetables might not be necessary and could deprive you of essential nutrients.
• Limit Sugary Drinks: Sugary beverages like sodas and fruit juices can contribute to stone formation. Opt for water, unsweetened teas, and diluted fruit juices instead.

Obesity is a risk factor for kidney stones. Maintaining a healthy weight through a balanced diet and regular exercise can help reduce the risk. Don’t skimp on fruits and vegetables. These are packed with vitamins, minerals, and fiber, which can promote overall health and potentially reduce kidney stone risk. Stay Active. Regular physical activity is essential for overall health and may help reduce the risk of kidney stones.

Additionally, consider using a Citrate Supplement. Citrate binds to calcium in the urine, preventing stone formation. However, consult with your doctor before taking any supplements to ensure it’s safe and appropriate for you. If you have a medical condition that contributes to kidney stones, following your doctor’s recommended medications can help prevent their formation. 

Address Underlying Conditions. If you have a medical condition like gout or UTIs that increase your risk of kidney stones, proper management of these conditions can be crucial for prevention.

How are Kidney Stones Diagnosed?

Doctors diagnose kidney stones using a combination of techniques to gather information and create a clear picture. 

The doctor will first discuss your symptoms, medical history, and any risk factors for kidney stones. A physical exam might be conducted to assess for tenderness or pain in the flank or abdomen.

Urinalysis is a basic but informative test that is often used. A urine sample is analyzed for the presence of blood, white blood cells, and stone-forming minerals. The presence of blood cells might indicate irritation from a stone, while high levels of certain minerals could suggest a predisposition to specific stone types.

Depending on the severity of your symptoms and the doctor’s initial assessment, imaging tests might be used to visualize the urinary tract and identify potential stones.

• Abdominal X-ray: This is a quick and relatively inexpensive test. While not the most detailed, it can detect some types of kidney stones, particularly those containing calcium.
• Ultrasound: This painless test uses sound waves to create images of your kidneys, ureters, and bladder. It’s helpful for detecting stones but might not be the best option for all types, especially those composed of uric acid. Ultrasound also offers the advantage of being safe for pregnant women.
• CT Scan (Computed Tomography): This non-invasive scan uses X-rays to create detailed cross-sectional images of your urinary tract. It’s considered the gold standard for diagnosing kidney stones and can detect most types, including uric acid stones. However, CT scans involve radiation exposure, so doctors might weigh the risks and benefits before using them, especially for younger patients or those with a lower likelihood of having stones.

In some cases, blood tests might be ordered to check for underlying conditions that could contribute to kidney stones, such as gout or hyperparathyroidism. Additionally, blood tests can assess your kidney function.

How are Kidney Stones Treated?

Several factors influence the treatment approach for kidney stones, and the options available can be categorized into conservative and interventional methods. Here’s a breakdown of the key influences and treatment options:

Factors Influencing Treatment:

• Size and Location of the Stone: Smaller stones (less than 5 mm) are more likely to pass on their own with conservative management. Larger stones or those lodged in a narrow part of the ureter might require intervention to facilitate passage or removal.
• Type of Stone: The stone’s composition can influence treatment choices. For example, medications to help pass the stone might be more effective for certain types like calcium oxalate stones.
• Severity of Symptoms: The intensity of pain and presence of complications like infection will influence treatment decisions. Severe pain might necessitate pain management medications or quicker intervention to remove the stone.
• Overall Health: Underlying medical conditions and your general health status are considered. For instance, someone with a bleeding disorder might not be a good candidate for certain procedures.

Treatment Options:

Conservative Management:

• Pain Management: This is often the first step, using medications like NSAIDs or stronger pain relievers to manage discomfort.
• Hydration: Increasing fluid intake is crucial to help flush out the stone. Doctors might recommend drinking plenty of water and possibly even intravenous fluids for severe dehydration.
• Medications to Help Pass the Stone: Alpha-blockers can relax the muscles in the ureter, allowing the stone to pass more easily. This might be an option for smaller stones.

Interventional Measures:

Lithotripsy is a non-invasive procedure that uses shock waves to break down larger stones into smaller fragments that can then pass through the urinary tract. There are different types of lithotripsy depending on the stone’s location and size. Shock wave lithotripsy (SWL) is the most common type, using shock waves from outside the body to fragment the stone. 

Another lithotripsy method is Ureteroscopy with laser lithotripsy. With this procedure, a thin scope is inserted through the urethra and bladder to reach the ureter and visualize the stone. Lasers can then be used to break down the stone.

If the stone is too large or doesn’t respond to other treatments, surgery might be necessary. Minimally invasive options include Percutaneous nephrolithotomy (PCNL). A thin instrument is inserted through a small incision in the back to reach the kidney and remove the stone. Although having a similar procedure to ureteroscopy with laser lithotripsy, regular ureteroscopy is used for larger stones that require removal instead of fragmentation. 

In rare cases, open surgery might be needed for complex situations where minimally invasive approaches are not suitable.

What Medications are Most Often Prescribed for Kidney Stones? 

The specific medications prescribed for kidney stones depend on the type of stone and the treatment plan. Here’s a breakdown of some commonly used medications:

1. Pain Management:
   • Nonsteroidal Anti-inflammatory Drugs (NSAIDs): These medications, like ibuprofen or naproxen, are often the first line of defense for managing pain associated with kidney stones.
2. Medications to Help Pass the Stone:
   1. Alpha-Blockers: Medications like tamsulosin (Flomax) can relax the muscles in the ureter, allowing the stone to pass more easily. This is typically used for smaller stones.
3. Medications to Prevent Stone Formation:
   • Potassium Citrate or Sodium Citrate: These medications bind to calcium in the urine, helping prevent calcium oxalate stones from forming or growing larger. They may also be helpful for preventing uric acid stones.
   • Thiazide Diuretics: Diuretics like hydrochlorothiazide (HCTZ) can help reduce the amount of calcium released into the urine. This might be beneficial for preventing calcium oxalate stones in people with high urinary calcium levels.
   • Allopurinol (Zyloprim): This medication is used to lower uric acid levels in the blood and urine, which can help prevent uric acid stones in people with gout or a high intake of animal protein.