What kidney stones are
Kidney stones are small, hard lumps made of minerals and salts that form inside the kidney. They start as tiny crystals when urine has more minerals than the water can keep dissolved. Over weeks or months these crystals stick together and grow. Stones can be as small as a grain of sand or as big as a marble.
Most stones are made of calcium oxalate. Others are made of uric acid, calcium phosphate or, less often, other substances. Small stones often pass out in the urine on their own, while larger ones can get stuck in the tube from the kidney to the bladder (the ureter) and cause severe pain.
Why stones form
The biggest cause is not drinking enough water, which makes urine dark and concentrated. This is why kidney stones are common in hot parts of India, especially in summer and among people who work outdoors, travel a lot or avoid drinking water to skip toilet breaks. Once you have had one stone, the chance of another is higher.
- Low water intake and heavy sweating
- A diet high in salt, packaged snacks and animal protein
- Excess body weight, diabetes and gout
- A family history of stones
- Repeated urine infections and some bowel conditions
- Some medicines and long-term high-dose supplements, which a doctor can review
Symptoms of kidney stones
A stone that is sitting still in the kidney may cause no symptoms. When it moves into the ureter, it can cause sudden, very severe pain in the back or side, just below the ribs. This pain, called renal colic, comes in waves and may spread to the lower belly, groin or genitals. People often cannot sit still and may vomit.
Other signs include pink, red or brown urine, burning while passing urine, passing urine often or in small amounts, and cloudy or bad-smelling urine. Fever and chills with stone pain suggest infection behind a blocked kidney, which is an emergency.
Tests and diagnosis
A urine test looks for blood, crystals and infection. Blood tests check kidney function (creatinine), calcium and uric acid. An ultrasound of the abdomen is a quick, radiation-free first test and is preferred in pregnancy and in children. A CT scan (KUB) is the most accurate test for finding the size and position of a stone.
If you pass a stone, try to catch it by passing urine through a clean cloth or tea strainer and keep it dry. Stone analysis in a lab tells what the stone is made of. This helps the doctor plan diet changes and prevention, and may lead to a 24-hour urine test in people with repeated stones.
Treatment options for kidney stones
Small stones usually pass on their own within a few weeks. Doctors control pain with painkillers, often NSAIDs such as diclofenac, and may prescribe a medicine such as tamsulosin to relax the ureter and help the stone pass. Drink the amount of water your doctor recommends while waiting. Painkillers like NSAIDs are not suitable for everyone, especially people with kidney disease or in pregnancy.
Larger stones, or stones that block urine flow or cause infection, need a procedure. Options include shock wave treatment from outside the body (ESWL), a thin telescope passed through the urinary tract to break the stone with a laser (URS or RIRS), or keyhole surgery through the back for big stones (PCNL).
Preventing stones from coming back
Prevention is simple but must be kept up for life. Aim to drink enough water to keep your urine pale yellow through the day, and more in summer or after sweating. Your doctor may suggest specific diet changes based on your stone type and urine tests, so avoid cutting out healthy foods on your own.
- Carry a water bottle and drink regularly, not only when thirsty
- Reduce salt, pickles, papad and packaged salty snacks
- Limit red meat and organ meat if you have uric acid stones
- Get calcium from normal food such as milk and curd; do not avoid it
- Stay active and keep a healthy weight
When to see a doctor for kidney stones
See a doctor for any severe side or back pain, blood in the urine or repeated urine infections. After a stone episode, follow up even if the pain has gone, because a stone can silently block the kidney. Pregnant women, children and people with a single kidney or kidney disease need prompt review. A doctor or pharmacist can advise on safe pain relief and prevention.
Medicines doctors commonly use
Only your doctor can decide which medicine, dose and combination is right for you.
- NSAID painkillers such as diclofenacRelieve kidney stone pain and reduce swelling in the ureter.Only as advised by a doctor; not suitable in kidney disease, stomach ulcers or pregnancy.
- Alpha blockers such as tamsulosinRelax the muscle of the ureter to help small stones pass.Only on a doctor's prescription; may cause dizziness on standing.
- Anti-nausea medicines such as ondansetronControl vomiting during severe stone pain.Use as your doctor advises.
- Potassium citrateMakes urine less acidic and helps prevent some types of stones.Only on a doctor's prescription after blood and urine tests.
- AllopurinolLowers uric acid to prevent uric acid stones.Only on a doctor's prescription; do not stop on your own.
See a doctor urgently if
- See a doctor urgently if you have stone pain with fever, chills or shivering.
- See a doctor urgently if you cannot pass urine or pass very little.
- See a doctor urgently if pain is so severe that painkillers do not help or you keep vomiting.
- See a doctor urgently if you have only one kidney, or are pregnant, and develop stone symptoms.
- See a doctor soon if you see blood in your urine, even without pain.
Tests that may help
This article is general health information, not medical advice. Do not start, stop or combine medicines on your own — always follow your doctor's prescription and ask your pharmacist if unsure.