Kidney stones: symptoms, tests, treatment and prevention

What kidney stones are, the pain they cause, the scans that find them, how they are passed or removed, and how to stop new ones forming.

Also known as: Calculus of kidney; Calculus, kidney; Calculus, renal; Kidney calculi; Kidney stone; Nephrolith

What kidney stones are

Urine carries dissolved minerals and salts out of the body. When urine is concentrated, or contains too much of certain substances, these can form crystals that stick together into a hard stone. Stones form in the kidney and can range from the size of a grain of sand to larger than a marble.

A stone sitting quietly in the kidney may cause no trouble for years. Pain usually starts when a stone moves into the ureter, the narrow tube that carries urine from the kidney to the bladder, and blocks the flow. Most stones are made of calcium oxalate; others are made of uric acid, calcium phosphate, struvite (linked to infection) or, rarely, cystine. Knowing the type helps prevent new ones.

Many people who have had one stone will form another within some years, so treatment is only half the job. Prevention is the other half.

Symptoms

• Severe pain in the side or back, below the ribs, that comes in waves and may spread to the lower abdomen or groin — often called renal colic
• Restlessness: unlike many types of pain, people with renal colic often cannot find a comfortable position
• Blood in the urine — pink, red or brown, or seen only on a urine test
• Nausea and vomiting
• Burning when passing urine, or a frequent urge to pass urine as the stone nears the bladder

Fever or shivering with stone pain is a warning sign of infection behind a blocked kidney, which needs urgent treatment.

Causes and who is at risk in India

The most important single factor is not drinking enough fluid, especially in a hot climate. People who work outdoors, travel long hours, or avoid drinking water because toilets are not available are at particular risk. Other factors include:

• A previous stone, or a family history of stones
• A diet high in salt, animal protein or sugary drinks
• Excess weight, diabetes and gout
• Repeated urine infections
• Bowel conditions or surgery that affect absorption
• Some medicines and supplements — ask your doctor before taking high-dose calcium or vitamin C supplements, but do not stop a prescribed medicine on your own
• Rare inherited conditions, particularly in children with stones

Cutting out dietary calcium, a common instinct, usually backfires: normal amounts of calcium in food bind oxalate in the gut and may lower the risk of calcium oxalate stones.

How it is diagnosed

• Urine test — looks for blood, crystals and infection.
• Ultrasound — no radiation, widely available, and often the first scan, especially in pregnancy and children. It can miss small stones in the ureter.
• Non-contrast CT scan — often called a CT KUB. It is the most accurate scan for showing the size and position of a stone, and is used when the diagnosis or treatment plan depends on detail.
• Kidney function blood test — checks that the kidneys are working well, and guides treatment.
• Stone analysis — if you pass a stone, strain your urine and keep it; the laboratory can tell you what it is made of.

If you have formed more than one stone, or have a strong family history, your doctor may arrange blood tests for calcium and uric acid and a urine collection over a day to look for the reason.

Which doctor to see

Stone pain is often first treated in an emergency department or by a general physician. A urologist treats stones that do not pass, are large, cause blockage or infection, or keep coming back. A nephrologist helps when stones are recurrent, linked to a metabolic problem, or affect kidney function.

You can find urologists in Bengaluru or nephrologists in Bengaluru on The Doctor Index, each with a registration you can check.

Treatment

Waiting for a small stone to pass

Many small stones pass by themselves within days to weeks. Watchful waiting with pain relief, anti-sickness medicine and enough fluid is reasonable if the pain is controlled, there is no infection and the kidney is working. Medical expulsive therapy uses a medicine (an alpha blocker) that relaxes the ureter and can help some stones pass. Your doctor will set a time limit and arrange a repeat scan.

Procedures to remove or break stones

If a stone is too large to pass, does not move, causes infection or blockage, or the pain cannot be controlled, a procedure is needed. The choice depends on the size, position, hardness and type of stone, and on your general health.

• Shock wave lithotripsy — sound waves from outside the body break the stone into fragments that are then passed in the urine. No cut is made.
• Ureteroscopy — a thin telescope is passed through the urethra and bladder into the ureter or kidney, and the stone is broken with a laser and removed.
• Percutaneous nephrolithotomy — for large kidney stones, a small cut in the back gives direct access to the kidney to break up and remove the stone.

A thin tube called a stent is sometimes left in the ureter for a short time afterwards. It must be removed or changed as planned — a forgotten stent can cause serious problems, so keep a note of when it is due.

Preventing new stones

• Drink enough fluid through the day that your urine stays pale; more in hot weather or when sweating
• Cut down on salt, including in pickles, papads, packaged snacks and restaurant food
• Keep normal amounts of dairy and other calcium-rich food in your diet
• Limit sugary and cola drinks and large portions of meat
• If your stones are of a particular type, your doctor or a dietitian will give specific advice, and sometimes medicines to reduce the risk

Beer, home remedies and 'stone-dissolving' products are not a substitute for assessment. Alcohol dehydrates you, and delaying treatment of a blocking stone can damage the kidney.

When it is an emergency

Call 112 or 108, or go to the nearest emergency department, for:

• Stone pain with fever, chills or shivering
• Pain that is not controlled by the treatment you have been given
• Vomiting so much that you cannot keep fluids down
• Passing little or no urine
• Stone symptoms if you have only one kidney, a kidney transplant, or are pregnant

Questions to ask at your appointment

• How big is the stone, where is it, and is it likely to pass?
• How long should we wait before treating it?
• Which procedure suits my stone, and why?
• Will I have a stent, and when must it come out?
• What is my stone made of, and what should I change to prevent another?

Common questions

All urology conditions →

Sources

• MedlinePlus, US National Library of Medicine — Kidney Stones
• Urology Care Foundation (American Urological Association) — Kidney Stones
• MedlinePlus, National Library of Medicine — Kidney Stones — Public-domain health-topic summary
• MedlinePlus Genetics — Kidney stones — Public-domain Genetics summary

Kidney stones: symptoms, tests, treatment and prevention is original text by The Doctor Index; the compiled source draft was used for research. Source: MedlinePlus, National Library of Medicine. Orphadata Science: Free access data from Orphanet. © INSERM 1999; July 2026 data, CC BY 4.0. This product uses the Human Phenotype Ontology (hp/releases/2026-09-01). Only sources listed for this article apply. Source material has been selected and arranged; HPO definitions are reproduced without alteration. No source organisation endorses this compilation. Köhler S et al. The Human Phenotype Ontology project: linking molecular biology and disease through phenotype data. Nucleic Acids Research 2014;42(D1):D966–D974. doi:10.1093/nar/gkt1026.

General information, not advice about your situation. Errors can be reported through the corrections process. Reference TDI-C-1363.