Kidney Stones: What They Are, What Causes Them, and How They Move

Kidney stones are hard deposits made of minerals and salts that form in the kidneys and may travel through the urinary tract. They can range from silent and small to very painful, but most cases can be managed effectively with timely medical care.

Overview

Kidney stones are solid, pebble-like deposits that form when certain substances in the urine become concentrated and crystallize. These crystals can grow over time inside the kidney and may stay there or move into other parts of the urinary tract. The urinary tract includes the kidneys, ureters, bladder, and urethra.

A kidney stone may be as small as a grain of sand or much larger. Small stones can sometimes pass out of the body without being noticed. Larger stones may become stuck, especially in the ureter, which is the narrow tube that carries urine from the kidney to the bladder. This is often when symptoms begin.

Kidney stones are common and can affect adults of many ages. Although the pain can be intense, the condition is usually treatable. Understanding how stones form, what causes them, and how they move can help people recognize symptoms early and seek appropriate care.

Symptoms and How Kidney Stones Move

Many kidney stones do not cause symptoms while they remain inside the kidney. Symptoms often start when a stone leaves the kidney and enters the ureter. As the stone moves, it can irritate the lining of the urinary tract and partially or completely block the flow of urine. This blockage can cause the kidney to swell and the ureter to spasm, leading to pain.

The classic symptom is sudden, severe pain in the side or back, often just below the ribs. The pain may move toward the lower abdomen or groin as the stone travels downward. It often comes in waves and may change in intensity. Some people also feel restless and unable to find a comfortable position.

Other possible symptoms include:

• Blood in the urine, which may make urine look pink, red, or brown
• Pain or burning during urination
• Frequent urination or an urgent need to urinate
• Nausea and vomiting
• Cloudy or foul-smelling urine
• Reduced urine output if there is significant blockage

If a stone is accompanied by a urinary tract infection, fever and chills may occur. This combination needs prompt medical attention because infection plus blockage can become serious quickly.

Causes, Stone Types, and Risk Factors

Kidney stones form when urine contains more crystal-forming substances than the fluid can dilute. At the same time, urine may lack enough natural substances that help prevent crystals from sticking together. This creates the conditions for stone formation. In many people, more than one factor is involved.

There are several main types of kidney stones. Calcium stones are the most common, often in the form of calcium oxalate. Uric acid stones may develop in people who lose a lot of fluid, eat a high-purine diet, or have certain metabolic conditions. Struvite stones can form after some urinary infections. Cystine stones are rare and usually linked to an inherited condition.

Risk factors include not drinking enough fluids, a diet high in salt, obesity, digestive diseases that affect absorption, and a personal or family history of stones. Some medical conditions and medications can also increase risk. People who have had one stone are more likely to develop another in the future, so prevention is an important part of care.

Kidney stones may also be linked with other urinary conditions. In some cases, doctors may look for related problems such as urinary tract infection or evaluate whether an enlarged prostate or other structural issue is affecting urine flow.

Diagnosis

Diagnosis begins with a medical history and physical examination. A doctor will ask about the pattern of pain, previous stones, family history, fluid intake, diet, and any signs of infection. Urine and blood tests are commonly used to look for blood in the urine, signs of infection, kidney function changes, and substances that may promote stone formation.

Imaging tests help confirm the diagnosis and show the stone’s size and location. Ultrasound is often used, especially in situations where minimizing radiation is important. Computed tomography, commonly called CT, can provide very detailed images and is widely used when symptoms are severe or the diagnosis is uncertain. Some patients may also have plain X-rays, depending on the suspected stone type.

If a stone passes, the patient may be asked to collect it for analysis. Knowing the stone’s composition can help guide prevention. In people with repeated stones, doctors may recommend additional metabolic testing, such as a 24-hour urine collection, to identify treatable risk factors and reduce the likelihood of recurrence.

When more detailed evaluation is needed, imaging and specialist assessment may be part of a broader urology care plan, especially for recurrent stones or complicated cases.

Treatment Options

Treatment depends on several factors, including the stone’s size, type, location, the severity of symptoms, and whether there is blockage or infection. Small stones often pass on their own with time, fluids, pain relief, and careful follow-up. Doctors may also prescribe medication to help relax the ureter and make passage easier in selected cases.

Larger stones or stones causing persistent pain, infection, kidney function problems, or inability to pass urine may need a procedure. One common option is lithotripsy, which uses shock waves to break a stone into smaller pieces that can pass more easily. Another option is ureteroscopy, in which a thin instrument is passed through the urinary tract to remove or break the stone.

For very large or complex stones, especially those still in the kidney, a doctor may recommend percutaneous nephrolithotomy. This procedure removes the stone through a small incision in the back. In urgent situations, such as an infected blocked kidney, immediate drainage may be needed before definitive stone treatment.

After treatment, follow-up is important to make sure the stone has passed or been fully removed and that the kidneys are draining properly. Patients with repeated stones may need longer-term prevention planning based on stone analysis and metabolic evaluation.

Prevention and Self-care

Prevention is often possible, especially after the type of stone and personal risk factors are understood. The most widely recommended step is to drink enough fluids so the urine stays relatively dilute. For many people, this means increasing water intake throughout the day, though individual needs vary based on climate, activity, and medical conditions.

Dietary changes may also help. Depending on the stone type, a doctor may advise limiting excess salt, moderating animal protein, and adjusting intake of oxalate-rich foods. It is important not to make major dietary restrictions without guidance, because overly limiting calcium, for example, may not be helpful and can sometimes increase risk in certain people.

Maintaining a healthy weight and managing underlying conditions can also reduce recurrence. People who have repeated stones may benefit from targeted medication, but this depends on the stone type and laboratory findings. Self-care should focus on steady hydration, following the care plan, and attending follow-up appointments.

For international patients who need diagnosis or treatment, Acibadem International’s multidisciplinary specialists at JCI-accredited hospitals evaluate kidney stones and plan care based on the stone type, symptoms, and overall health needs.

When to See a Doctor

Medical assessment is important for anyone with severe side or back pain, blood in the urine, or pain that comes in waves and spreads toward the groin. While some small stones pass on their own, symptoms can overlap with other conditions, so a correct diagnosis matters.

Urgent care is needed if pain is accompanied by fever, chills, vomiting that prevents fluid intake, reduced urination, or difficulty passing urine. These signs may suggest infection, significant obstruction, or dehydration. Prompt treatment helps protect kidney function and lowers the risk of complications.

People with a history of stones should also seek medical advice if symptoms return, even if they seem familiar. Recurrent stones may require prevention strategies tailored to the stone type and personal risk factors. Early evaluation often makes treatment more straightforward and can improve comfort and recovery.

Frequently asked questions

What exactly is a kidney stone?

A kidney stone is a hard deposit made from minerals and salts that crystallize in the urine. It can form in the kidney and then stay there or move into the ureter, bladder, or urethra.

Why do kidney stones hurt so much when they move?

Pain usually begins when a stone enters the ureter and blocks urine flow. This can stretch the kidney, trigger muscle spasms in the ureter, and irritate the lining of the urinary tract, all of which can cause intense pain.

Can a kidney stone pass on its own?

Yes, many small stones can pass naturally, especially if they are not causing major blockage or infection. Whether this is likely depends on the stone’s size, location, and the person’s symptoms, so medical guidance is still important.

How long does it take for a kidney stone to pass?

The time varies widely. Some small stones pass within days, while others may take weeks or may not pass without treatment. A doctor can estimate the likelihood of passage based on imaging results.

Are all kidney stones made of calcium?

No. Calcium stones are the most common, but kidney stones can also be made of uric acid, struvite, or cystine. Identifying the type helps guide treatment and prevention.

Can drinking more water prevent kidney stones?

For many people, yes, better hydration lowers the risk because it helps dilute the urine and reduces crystal formation. However, prevention may also require diet changes or medication depending on the stone type and other risk factors.

When is a kidney stone an emergency?

A kidney stone needs urgent medical attention if there is fever, chills, severe uncontrolled pain, vomiting, very little urine, or trouble urinating. These symptoms can suggest infection, dehydration, or a dangerous blockage that should be treated promptly.

References

• National Institute of Diabetes and Digestive and Kidney Diseases
• National Kidney Foundation
• American Urological Association
• European Association of Urology
• Mayo Clinic

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.