What are Kidney Stones or Nephrolithiasis? Causes, Symptoms, and Treatments Explained

Kidney stones, medically referred to as nephrolithiasis, are hard mineral and salt deposits that form inside the kidneys. Although small, these stone-like formations can cause severe pain and discomfort, especially when passing through the urinary tract. Kidney stones are a common health problem that affects people across all age groups, and their incidence is increasing around the world. Understanding how kidney stones develop, what symptoms to look out for, and the available treatment and prevention methods can help reduce the risk of complications and improve quality of life for those affected.

Kidney stones are small, hard clumps that form in the kidneys when certain substances in the urine—like calcium, oxalate, and uric acid—get too concentrated. Over time, these substances can stick together and crystallize, forming stones that vary in size from a grain of sand to the size of a small pebble or even larger. Image Credit: Jehsomwang via Canva.com.

What Are Kidney Stones?

Kidney stones form when substances like calcium, oxalate, uric acid, or cystine become too concentrated in the urine and begin to crystallize. Over time, these crystals stick together and grow into solid stones that can range in size from a grain of sand to several centimeters across. Some stones stay in the kidneys and cause little to no symptoms, while others move into the ureters, the narrow tubes that carry urine from the kidneys to the bladder.

When a stone becomes lodged in a ureter, it can block the flow of urine and cause intense pain. Not all stones are made of the same substances, and identifying the type of stone can help guide treatment and prevention strategies.

Types of Kidney Stones

There are several types of kidney stones, and each type forms for different reasons. The most common type is the calcium oxalate stone, which develops when calcium combines with oxalate in the urine. Calcium phosphate stones are less common and tend to form in people with certain metabolic conditions or urinary tract abnormalities. Uric acid stones form when urine becomes too acidic, often due to high purine intake from foods such as red meat or shellfish.

Struvite stones are associated with urinary tract infections and tend to grow rapidly, sometimes forming large, branching stones known as staghorn calculi. Cystine stones are rare and occur in people with a hereditary disorder that causes cystine to leak into the urine.

What Causes Kidney Stones?

Kidney stones are caused by a combination of factors that influence the concentration and balance of minerals in the urine. One of the most common causes is not drinking enough water, which leads to low urine volume and makes it easier for crystals to form. A diet high in sodium, protein, or oxalate-rich foods can also increase the risk. Medical conditions such as hyperparathyroidism, inflammatory bowel disease, and chronic urinary tract infections may make stone formation more likely.

Certain medications, including some diuretics and calcium-based antacids, can contribute to stone formation in susceptible individuals. Genetics can also play a role, with some people inheriting a tendency to form stones. Although kidney stones can affect anyone, individuals with a family history of stones or those who have had stones before are at higher risk of recurrence.

Risk Factors for Developing Kidney Stones

Several risk factors make a person more likely to develop kidney stones. Dehydration is one of the leading contributors, as low fluid intake reduces urine output and increases the concentration of stone-forming substances. People who live in hot climates or who sweat excessively without adequate fluid replacement may be more susceptible. Dietary habits also matter.

Diets high in animal protein, sodium, or processed foods can alter the balance of chemicals in the urine and promote stone formation. Obesity, metabolic syndrome, and conditions like gout can further raise the risk by changing how the kidneys process waste. Certain digestive conditions, such as Crohn’s disease or a history of bariatric surgery, may also affect how the body absorbs calcium and other minerals, increasing the risk of stone formation.

Symptoms of Kidney Stones

The symptoms of kidney stones vary depending on the size and location of the stone. When a stone remains in the kidney and does not block urine flow, it may not cause any noticeable symptoms. However, when a stone moves into the ureter, it can lead to sharp, cramping pain in the back or side, often radiating to the lower abdomen or groin. This type of pain is commonly referred to as renal colic and may come in waves.

Other symptoms can include blood in the urine, which may appear pink or reddish, nausea, vomiting, a persistent urge to urinate, or pain during urination. If a stone causes a urinary tract infection, symptoms like fever, chills, and cloudy or foul-smelling urine may occur. In some cases, the pain can be so severe that emergency care is required.

How Kidney Stones Are Diagnosed

Doctors typically begin the diagnostic process by reviewing the patient’s medical history and conducting a physical examination. Urinalysis can help detect blood, infection, or crystals that suggest the presence of a stone. Blood tests may be used to check kidney function and identify elevated levels of calcium, uric acid, or other substances associated with stone formation. Imaging tests are essential for confirming the diagnosis and determining the size and location of the stone. 

A non-contrast helical computed tomography (CT) scan is considered the most accurate method for detecting kidney stones. In some cases, an ultrasound may be used as a first step, particularly in pregnant individuals or those needing less radiation exposure. An X-ray called a KUB (kidney, ureter, bladder) may also be used to track certain types of stones over time. These diagnostic tools help guide treatment and determine whether surgical intervention is needed.

Treatment Options for Kidney Stones

Treatment for kidney stones depends on the size, location, and type of stone, as well as the severity of symptoms. Small stones often pass on their own with increased fluid intake and pain management. Drinking two to three liters of water daily (roughly 68 to 101 ounces) helps flush the urinary tract and may help small stones pass more easily. Over-the-counter or prescription medications such as nonsteroidal anti-inflammatory drugs can relieve pain.

Alpha-blockers may be prescribed to relax the muscles in the ureter and make it easier for stones to pass. Larger stones or those causing severe symptoms may require more active treatment. Extracorporeal shock wave lithotripsy (ESWL) uses sound waves to break stones into smaller pieces that can be passed naturally. Ureteroscopy involves inserting a thin tube through the urethra and bladder to reach and remove or break the stone. In some cases, percutaneous nephrolithotomy, a surgical procedure performed through a small incision in the back, is needed for very large or complex stones.

Home Remedies and Natural Ways to Pass Stones

For small stones that are likely to pass on their own, home remedies can support the process. Staying well-hydrated is the most important step, as it increases urine volume and helps flush out small stones. Drinking citrus-based fluids like lemonade or orange juice may also help because citrate can prevent crystal formation. Some people use herbal remedies like chanca piedra, also known as the “stone breaker” plant, although scientific evidence supporting its effectiveness is limited.

Applying heat to the affected area may ease pain, while walking or light activity may encourage stone movement. It is important to note that home remedies are best used for temporary comfort and should not replace medical treatment. Consulting a doctor is essential before trying any home treatment, especially for those with a history of complications or other medical conditions.

Can Kidney Stones Go Away on Their Own?

Many kidney stones, particularly those smaller than 5 millimeters (about 0.2 inches), can pass on their own without the need for surgery. The time it takes for a stone to pass can vary from a few days to several weeks. Drinking plenty of fluids and using pain medication can help manage symptoms and support the body’s natural process.

Stones larger than 6 millimeters (around 0.24 inches) are less likely to pass without intervention and may cause obstruction or infection. Even when stones do pass naturally, it is important to follow up with a healthcare provider to analyze the stone, identify its composition, and develop a plan to prevent future episodes. Leaving a stone untreated, even a small one, can increase the risk of repeated episodes or damage to the kidneys over time.

Preventing Kidney Stones

Preventing kidney stones is often possible through changes in diet, lifestyle, and fluid intake. Drinking enough water to produce at least two liters (about half a gallon) of urine per day is the cornerstone of prevention. People who have had stones before may need to drink even more. Reducing salt intake helps lower calcium levels in the urine, while limiting foods high in oxalate, such as spinach, beets, and nuts, may prevent calcium oxalate stones from forming.

A balanced intake of calcium through food—not supplements—can actually help reduce stone risk by binding with oxalate in the digestive tract. Those with uric acid stones may benefit from reducing purine-rich foods like red meat, organ meats, and shellfish. For people with recurrent stones, doctors may recommend medications that alter urine composition and reduce stone-forming substances. Regular follow-up with a healthcare provider, urine testing, and sometimes imaging studies are all important for monitoring and preventing recurrence.

Complications of Untreated Kidney Stones

When kidney stones are not diagnosed or treated appropriately, they can lead to a range of complications. Obstruction of the urinary tract can cause swelling in the kidney, a condition known as hydronephrosis, which may lead to permanent kidney damage if not relieved. Persistent obstruction increases the risk of infection, which can spread to the bloodstream and cause sepsis—a medical emergency.

In some cases, stones can erode or injure the lining of the urinary tract, leading to bleeding or scarring. Recurrent stones can also reduce overall kidney function over time and may contribute to chronic kidney disease. Early diagnosis, regular follow-up, and appropriate treatment are key to avoiding these complications and preserving long-term kidney health.

Myths and Misunderstandings About Kidney Stones

There are several common misconceptions about kidney stones that can lead to confusion or delayed treatment. One myth is that only men get kidney stones. While men are slightly more likely to develop them, women are also affected, and their risk increases with certain conditions like urinary tract infections or pregnancy. Another misconception is that drinking milk or consuming calcium-rich foods causes stones. In fact, moderate calcium intake from food can help prevent stones by reducing oxalate absorption.

Some believe that once a stone passes, the problem is solved. However, having one stone significantly increases the risk of having another, so ongoing prevention strategies are crucial. Lastly, many assume that drinking large amounts of soda or tea causes kidney stones. While excessive consumption of sugar-sweetened or high-oxalate beverages may increase risk, they are not the sole cause. Balance and moderation, along with proper hydration, are key to reducing the likelihood of stone formation.

Conclusion

Kidney stones are a common and often painful condition, but they are also manageable and preventable with the right knowledge and care. Understanding the causes, recognizing symptoms early, and seeking timely treatment can help reduce the risk of complications and improve outcomes. Whether you are passing a stone naturally, undergoing a medical procedure, or trying to prevent future episodes, making informed choices about hydration, diet, and follow-up care is essential. With medical advances and greater awareness, most people affected by kidney stones can return to normal activities and protect their long-term kidney health. Staying alert to symptoms and adopting preventive habits can make a lasting difference in reducing the burden of this increasingly common condition.

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