Condition guide
Kidney Stones
Also known as: Nephrolithiasis, Urolithiasis, Renal calculi, Ureteric stones
In brief
Kidney stones are hard deposits of minerals and salts that form inside the kidney. Small stones often pass on their own, but stones that block the flow of urine can cause severe pain, infection or kidney damage and may need treatment by a urologist.
Medically reviewed by Dr. Atip Chatsudthipong, MD on
Written by Editorial teamPublished Updated
What are kidney stones?
Kidney stones form when substances in the urine — such as calcium, oxalate, uric acid and phosphate — become too concentrated and crystallise. Over time the crystals can grow into stones ranging from the size of a grain of sand to, occasionally, several centimetres.
A stone can stay in the kidney without causing symptoms for a long time. Problems usually begin when a stone moves into the ureter, the narrow tube that carries urine from the kidney to the bladder, and partly or completely blocks the flow of urine.
Types of kidney stone
| Stone type | How common | Typical contributing factors |
|---|---|---|
| Calcium oxalate | Most common | Low urine volume, high-sodium diet, high urinary oxalate or calcium, low urinary citrate |
| Calcium phosphate | Common | Certain metabolic conditions and high urine pH |
| Uric acid | Less common | Persistently acidic urine, gout, diets high in animal protein, diabetes and obesity |
| Struvite (infection stones) | Uncommon | Chronic urinary infection with specific bacteria |
| Cystine | Rare | An inherited condition (cystinuria) |
Knowing the stone type matters because it guides prevention. Whenever possible, a passed or removed stone should be sent for laboratory analysis.
What are the symptoms of kidney stones?
Small stones that stay in the kidney may cause no symptoms at all and are often discovered on a scan done for another reason. When a stone moves or causes a blockage, typical symptoms include:
- Sudden, severe pain in the side or back, below the ribs, often coming in waves (renal colic)
- Pain that spreads to the lower abdomen or groin
- Pink, red or brown urine, or blood seen only on a urine test
- Nausea and vomiting
- A frequent or urgent need to urinate, or burning when passing urine as the stone nears the bladder
- Difficulty finding a comfortable position
Read more in What are the early signs of kidney stones?
What causes kidney stones, and who is at risk?
Most stones result from a combination of factors rather than a single cause. Common risk factors include:
- Not drinking enough fluid, particularly in hot climates such as Thailand's, where fluid is lost through sweating
- A diet high in salt (sodium) or animal protein
- A personal or family history of kidney stones
- Obesity, diabetes, gout and some bowel conditions or bowel surgery
- Certain metabolic or inherited conditions, such as hyperparathyroidism or cystinuria
- Recurrent urinary tract infections (for struvite stones)
- Some medicines and supplements — your doctor will review what you take
Stones are common and can affect anyone. Without preventive measures, many people who have had one stone will develop another within the following years, which is why prevention is part of every treatment plan.
How are kidney stones diagnosed?
Diagnosis combines your history and examination with tests that confirm the stone, its size and position, and whether it is causing a blockage or infection.
- Non-contrast CT scan — the most accurate test for detecting stones; low-dose protocols are commonly used
- Ultrasound — avoids radiation and is preferred in pregnancy and children; it can also show swelling of the kidney (hydronephrosis)
- Urine tests — to look for blood, infection and crystals
- Blood tests — kidney function, and calcium and uric acid levels
- Stone analysis — on any stone that is passed or removed
- 24-hour urine collection — for people with recurrent stones or a higher risk of recurrence, to identify correctable causes
How are kidney stones treated?
Treatment depends on the stone's size, location and composition, how much it is blocking the kidney, whether infection is present, and your own preferences and health. Guidelines from the American Urological Association (AUA) and the European Association of Urology (EAU) describe the following options.
Watchful waiting and medication
Many small stones — particularly those under about 5 mm — pass on their own within a few weeks. Pain relief, plenty of fluids and, for some stones in the lower ureter, a medicine called an alpha-blocker (medical expulsive therapy) can help. Regular follow-up is important to confirm the stone has passed and the kidney is draining normally.
Procedures to remove or break up stones
| Procedure | How it works | Often considered for |
|---|---|---|
| Ureteroscopy with laser lithotripsy | A thin telescope is passed through the urinary tract — no skin incision — and a laser breaks the stone into fragments or dust | Stones in the ureter and many kidney stones |
| Shock wave lithotripsy (SWL) | Focused shock waves from outside the body break the stone, and fragments pass in the urine | Selected smaller kidney and upper-ureter stones |
| Percutaneous nephrolithotomy (PCNL) | The kidney is reached through a small incision in the back to remove stones directly | Large or complex kidney stones (generally over about 2 cm) |
For a side-by-side comparison, see Kidney stone treatment options explained.
Preventing new stones
- Drink enough fluid to produce at least about 2.5 litres of urine a day (more in hot weather or with exercise)
- Reduce salt intake
- Keep dietary calcium at normal levels — restricting calcium is not generally recommended for calcium stones
- Moderate animal protein and, if advised, foods very high in oxalate
- Medication such as thiazides, potassium citrate or allopurinol when tests show a specific risk
When should you seek medical attention?
Go to an emergency department immediately if you have:
- Kidney stone pain together with fever, chills or shivering — a blocked, infected kidney is a medical emergency
- Severe pain that is not controlled by pain relief, or persistent vomiting
- Very little or no urine
- A known stone and only one functioning kidney
Arrange a consultation with a urologist if a stone has not passed within a few weeks, if you have repeated episodes, if a stone is found incidentally on a scan, or if you would like advice on prevention.
How Dr. Atip can help
Kidney stones are one of Dr. Atip's listed clinical interests. At a consultation at Bumrungrad International Hospital he will review your symptoms and imaging, explain which options are realistic for your stone, and agree a plan with you — including how to reduce the chance of further stones.
If you are travelling to Bangkok, bring copies of previous scans (on disc or via an image-sharing link), reports and a list of your current medicines.
Frequently asked questions
What does kidney stone pain feel like?
Kidney stone pain is typically sudden and severe, felt in the side or back below the ribs, and often spreads to the lower abdomen or groin. It tends to come in waves as the ureter contracts around the stone, and many people find it hard to keep still.
Can kidney stones pass on their own?
Yes. Many small stones, particularly those under about 5 mm, pass on their own within a few weeks with fluids and pain relief. Larger stones are less likely to pass and may need a procedure. Your urologist will advise based on the stone's size and position.
When is surgery necessary for kidney stones?
A procedure is usually recommended when a stone is unlikely to pass because of its size, has not passed after a period of observation, causes uncontrolled pain, is blocking an infected kidney, or affects kidney function. Large stones in the kidney may also be treated before they cause problems.
What is laser lithotripsy?
Laser lithotripsy uses laser energy, delivered through a thin fibre during ureteroscopy or percutaneous surgery, to break a stone into small fragments or fine dust so it can be removed or passed in the urine.
How long does recovery take after kidney stone treatment?
After ureteroscopy many people go home the same day or the next day and return to light activities within a few days. If a temporary ureteral stent is placed, some discomfort and urinary frequency are common until it is removed. Recovery after PCNL usually takes longer. Your urologist will give individual advice.
Can kidney stones be prevented?
The risk of new stones can often be reduced by drinking enough fluid, limiting salt, keeping a normal calcium intake and, for some people, taking medication based on stone analysis and urine tests.
References
- 1.Assimos D, et al. Surgical Management of Stones: American Urological Association/Endourological Society Guideline, Part I. J Urol. 2016;196(4):1153–1160. (opens in a new tab)
- 2.Pearle MS, et al. Medical Management of Kidney Stones: AUA Guideline. J Urol. 2014;192(2):316–324. (opens in a new tab)
- 3.European Association of Urology. EAU Guidelines on Urolithiasis. (opens in a new tab)
- 4.National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Kidney Stones. (opens in a new tab)
- 5.NIDDK. Treatment for Kidney Stones. (opens in a new tab)
This information is for general education and does not replace a consultation with a qualified doctor. If you have severe symptoms, seek emergency care (in Thailand, call 1669). See our medical disclaimer.