Kidney Stones

What is kidney stones?

Kidney stones, known medically as renal calculi or nephrolithiasis, are hard deposits of minerals and salts that form inside the kidneys. The kidneys filter waste products from the blood and pass them into the urine. When urine contains more crystal-forming substances — such as calcium, oxalate, and uric acid — than the fluid in the urine can dilute, these substances can stick together and gradually build into a solid stone. Stones can range in size from a grain of sand to, in rare cases, a stone large enough to fill part of the kidney’s internal drainage system.

So, what is kidney stones as a diagnosis? The ICD-10 code N20.0 refers specifically to a calculus (stone) of the kidney itself. Stones can stay in the kidney without causing problems, or they can travel down the ureter — the narrow tube that carries urine from the kidney to the bladder. It is often during this journey that stones cause intense pain and other symptoms.

Kidney stones are a common condition worldwide. They can affect people of any age, including children, but are most often diagnosed in adults between their 30s and 60s. Men have historically been affected more often than women, although the gap has narrowed in many populations. People who have had one kidney stone have a meaningfully higher chance of forming another one later in life, which is why prevention is an important part of care.

There are several types of kidney stones, and the type influences both cause and treatment:

• Calcium stones — the most common type, usually made of calcium oxalate and sometimes calcium phosphate.
• Uric acid stones — more likely in people who lose too much fluid, eat a diet high in animal protein, or have conditions such as gout (a form of arthritis caused by uric acid crystals).
• Struvite stones — linked to certain urinary tract infections; they can grow quickly and become large.
• Cystine stones — rare, caused by an inherited disorder called cystinuria in which the kidneys leak a specific amino acid into the urine.

Symptoms

Kidney stones symptoms vary widely depending on the size of the stone and, most importantly, where it is located. A stone that sits quietly inside the kidney may cause no symptoms at all and may only be discovered by chance on an imaging scan done for another reason. Symptoms usually begin when a stone moves within the kidney or enters the ureter, where it can block the flow of urine and cause the kidney to swell and the ureter to spasm.

Common symptoms include:

• Severe, cramping pain in the side and back, below the ribs — often called renal colic. The pain frequently comes in waves and can shift as the stone moves.
• Pain radiating to the lower abdomen and groin.
• Pain or burning during urination, especially once the stone reaches the lower ureter or bladder.
• Blood in the urine — the urine may look pink, red, or brown, or blood may only be visible under a microscope.
• Cloudy or foul-smelling urine, which can suggest an accompanying infection.
• A frequent or urgent need to urinate, or passing only small amounts of urine at a time.
• Nausea and vomiting, which often accompany severe kidney pain.
• Fever and chills — a warning sign that an infection may be present.

Symptoms can also differ by stage. Early on, when a stone is still forming or resting in the kidney, many people feel nothing. As a stone begins to move, pain typically starts suddenly and can be extremely intense — many patients describe it as the worst pain they have experienced. When the stone travels lower in the ureter, urinary symptoms such as burning, urgency, and frequency tend to become more noticeable. Once a small stone passes into the bladder and then out of the body, symptoms often resolve quickly.

The type of stone can also matter. Struvite stones related to infection may cause fewer classic pain episodes but more infection-related symptoms, while uric acid and cystine stones can behave much like calcium stones. It is not possible to know the type of stone from symptoms alone, which is one reason medical evaluation is important.

Causes and risk factors

Kidney stones causes usually come down to an imbalance in the urine: either too many stone-forming substances, too little urine volume to keep them dissolved, or a shortage of natural substances in the urine that prevent crystals from sticking together. Often, no single cause is identified; instead, several factors combine.

Common risk factors include:

• Not drinking enough fluids. Low fluid intake produces concentrated urine, which makes crystal formation more likely. People who live in hot climates or who sweat heavily are at greater risk.
• Diet. Diets very high in salt (sodium), animal protein, or oxalate-rich foods (such as spinach, nuts, and certain teas) can raise the risk of some stone types. Excessive added sugar may also contribute.
• Personal or family history. Having had a stone before, or having close relatives with stones, increases the likelihood of forming one.
• Obesity. Higher body weight and related metabolic changes are associated with stone formation.
• Certain medical conditions. These include gout, hyperparathyroidism (overactivity of the parathyroid glands, which regulate calcium), recurrent urinary tract infections, inflammatory bowel disease, and conditions or surgeries that affect how the intestines absorb nutrients, such as gastric bypass.
• Certain medications and supplements. Some diuretics (water pills), calcium-based antacids taken in excess, high-dose vitamin C or vitamin D supplements, and a few other medicines may raise the risk in some people. Never stop a prescribed medicine on your own; discuss concerns with your doctor.
• Structural kidney problems. Anatomical variations that slow urine drainage can allow crystals to settle and grow.

Importantly, most people who form calcium stones do not need to avoid dietary calcium. In many cases, normal calcium intake with meals actually helps bind oxalate in the gut so that less of it reaches the urine. Dietary advice should always be individualized by a healthcare professional, ideally guided by the type of stone involved.

Diagnosis

Kidney stones diagnosis usually starts with a description of your symptoms and a physical examination. Because the classic pain of renal colic can resemble other conditions — such as appendicitis, gallbladder disease, or gynecological problems — doctors rely on tests to confirm that a stone is present, determine its size and location, and check for complications.

Tests your doctor may use include:

• Urine tests (urinalysis). A urine sample is checked for blood, crystals, and signs of infection. In people with recurrent stones, a 24-hour urine collection may be requested to measure the levels of calcium, oxalate, uric acid, citrate, and other substances over a full day.
• Blood tests. These can measure kidney function and check calcium, uric acid, and other values that may point to an underlying cause.
• CT scan (computed tomography). A low-dose non-contrast CT of the abdomen is widely considered the most accurate imaging test for detecting kidney and ureteral stones. It shows the stone’s exact size and position and can reveal swelling of the kidney caused by blockage.
• Ultrasound. This uses sound waves rather than radiation and is often the first choice for pregnant women, children, and situations where radiation should be minimized. It is very good at detecting kidney swelling, though small stones in the ureter can sometimes be missed.
• Plain X-ray. Some stones are visible on a standard abdominal X-ray, which can be useful for follow-up, but uric acid stones typically do not show up on plain films.
• Stone analysis. If you pass a stone, your doctor may ask you to catch it using a strainer so its chemical composition can be analyzed in a laboratory. Knowing the stone type guides prevention.

Based on these results, your care team assesses how large the stone is, whether it is likely to pass on its own, whether the kidney is blocked, and whether infection or reduced kidney function is present. These factors determine the treatment plan.

Treatment options

Kidney stones treatment depends on the stone’s size, location, and composition, the severity of symptoms, and whether complications such as infection or kidney blockage are present. In many hospitals, including Acibadem facilities, this condition is managed primarily by the urology department — the specialty focused on the urinary tract — often working alongside nephrology (kidney medicine) for prevention in people with recurrent stones.

Watchful waiting and supportive care

Small stones — generally those a few millimeters in size — often pass on their own through the urinary tract. If your doctor judges that the stone is likely to pass and there are no signs of infection or kidney damage, treatment may consist of drinking plenty of fluids, taking pain relievers such as nonsteroidal anti-inflammatory drugs (NSAIDs) when appropriate, and monitoring. Passing a stone can take days to several weeks, and your doctor will usually set a time limit after which further intervention is considered.

Medications

Doctors may prescribe a medicine called an alpha-blocker, which relaxes the muscles of the ureter and may help certain stones pass more easily; this approach is sometimes called medical expulsive therapy. For specific stone types, targeted medication can help: uric acid stones may sometimes be dissolved by making the urine less acidic with potassium citrate, and medicines such as allopurinol may be used to lower uric acid levels in selected patients. Antibiotics are used when a urinary infection is present. For long-term prevention, thiazide diuretics, citrate supplements, or other medicines may be recommended depending on the results of urine studies.

Procedures

When a stone is too large to pass, is causing ongoing blockage, or is associated with uncontrolled pain or infection, a procedure is usually needed. Common options include:

• Shock wave lithotripsy (SWL). Focused sound waves delivered from outside the body break the stone into small fragments that can then pass in the urine. It is noninvasive, though more than one session is sometimes needed and it works less well for very hard or very large stones.
• Ureteroscopy. A thin telescope is passed through the urethra and bladder into the ureter or kidney, with no incision. The stone is broken up, often with a laser, and fragments are removed. A temporary internal tube called a stent is sometimes left in place to keep urine flowing while the ureter heals.
• Percutaneous nephrolithotomy (PCNL). For large or complex kidney stones, the surgeon makes a small incision in the back and passes instruments directly into the kidney to fragment and remove the stone. This is done under general anesthesia and typically involves a short hospital stay.
• Emergency drainage. If a stone blocks the kidney and infection develops, urgent drainage with a stent or a tube placed through the skin (nephrostomy) may be required before the stone itself is treated, because an infected, blocked kidney can become life-threatening.

Surgery

Traditional open surgery for kidney stones is rarely needed today, because minimally invasive techniques handle the vast majority of cases. It may still be considered in unusual anatomical situations or when other approaches have not succeeded. Your urologist will explain which option fits your specific stone and overall health, along with the benefits and risks of each.

Living with kidney stones / outlook

For most people, the outlook after a kidney stone is good. Small stones often pass without lasting harm, and modern procedures remove or break up larger stones effectively in most cases. However, kidney stones have a well-known tendency to come back: a significant proportion of people who form one stone will form another within the following years. Because of this, long-term care focuses heavily on prevention.

General measures that doctors commonly recommend include:

• Drinking enough fluid throughout the day so that urine stays pale and dilute. Many doctors suggest aiming for roughly two to three liters of urine output daily, adjusted for your health conditions and climate.
• Reducing salt intake, since high sodium increases the amount of calcium in urine.
• Moderating animal protein, particularly for people with uric acid or calcium stones.
• Maintaining normal calcium intake from food rather than restricting it, unless a doctor advises otherwise.
• Managing weight and underlying conditions such as gout, diabetes, or high blood pressure.
• Taking preventive medication when prescribed, based on stone analysis and urine studies.

People with recurrent stones, a solitary kidney, reduced kidney function, or inherited stone disorders usually benefit from ongoing follow-up with a urologist or nephrologist, including periodic imaging and urine testing. While no plan can guarantee that stones will never return, consistent prevention meaningfully lowers the risk for many patients.

Frequently asked questions

What is kidney stones and how do they form?

Kidney stones are hard clumps of minerals and salts that form when urine becomes too concentrated, allowing substances such as calcium, oxalate, or uric acid to crystallize and stick together. They form inside the kidneys and may stay there or travel into the ureter, the tube leading to the bladder. Low fluid intake, diet, genetics, and certain medical conditions all influence how likely stones are to form.

Can kidney stones go away on their own?

Small stones often pass out of the body naturally in the urine, especially with good hydration and appropriate pain control. Larger stones are less likely to pass by themselves and may need a procedure. Some uric acid stones can be dissolved with medication that changes the acidity of the urine. Your doctor can estimate the chance of natural passage based on the stone’s size and position on imaging.

How serious are kidney stones?

Many kidney stones cause severe pain but no permanent damage once they pass or are removed. However, a stone that completely blocks urine flow can harm the kidney over time, and a blocked kidney combined with infection is a medical emergency. This is why stones that cause fever, persistent blockage, or uncontrollable symptoms need prompt treatment rather than watchful waiting.

What do kidney stones symptoms feel like?

The classic symptom is sudden, severe, cramping pain in the side or back below the ribs, often moving toward the lower abdomen and groin as the stone travels. Pain frequently comes in waves and may be accompanied by nausea, blood in the urine, burning during urination, or a frequent urge to urinate. Some stones cause no symptoms at all until they move.

How long does it take to recover after kidney stone treatment?

Recovery depends on the treatment used. After passing a stone naturally, most people feel better within days. Shock wave lithotripsy and ureteroscopy are usually outpatient or short-stay procedures, and many patients return to normal activities within days to a week or two, though a temporary stent can cause some discomfort. Percutaneous surgery for large stones typically involves a short hospital stay and a somewhat longer recovery. Your care team will give guidance tailored to your situation.

Will kidney stones come back after treatment?

Recurrence is common: many people who have had one stone will eventually form another. The risk can be reduced — though not eliminated — by drinking plenty of fluids, limiting salt, following individualized dietary advice, and taking preventive medication when prescribed. Analyzing a passed or removed stone helps doctors target prevention to your specific stone type.

What foods should I avoid if I have kidney stones?

There is no single diet for all stone types, so recommendations should come from your doctor or a dietitian. In general, limiting salt and very high amounts of animal protein helps many patients, and people with calcium oxalate stones may be advised to moderate high-oxalate foods such as spinach and nuts while keeping normal calcium intake from meals. Adequate fluid intake is the most consistently helpful measure for nearly all stone types.

When to see a doctor

Anyone with symptoms suggesting a kidney stone should be evaluated by a doctor, because proper diagnosis requires testing and imaging. Seek urgent or emergency medical care if you experience any of the following red-flag warning signs:

• Severe pain that makes it impossible to sit still, find a comfortable position, or function normally.
• Pain accompanied by fever or chills, which may indicate an infected, blocked kidney — a potentially life-threatening emergency.
• Persistent nausea and vomiting that prevents you from keeping fluids down.
• Visible blood in the urine, especially with pain.
• Inability to urinate or a marked drop in urine output.
• Pain in someone with a single kidney, a kidney transplant, or known reduced kidney function.
• Symptoms during pregnancy, which always warrant prompt medical assessment.

Even if your pain settles on its own, it is wise to follow up with a doctor. A stone may still be present, and identifying why it formed gives you the best chance of preventing the next one.