Kidney Stones: Passing a Stone and Preventing the Next One

The pain came on suddenly: a sharp, cramping pain in your side or back that moved toward your groin. You could not sit still. Maybe you ended up in the emergency department, and a scan showed a kidney stone. Now you want to know how to get it out, and how to make sure it never happens again. This guide explains both.

What kidney stones are

A kidney stone is a hard piece of material that forms in the kidney when certain substances in urine become too concentrated [3]. Stones can stay in the kidney or move into the ureter, the tube that carries urine to the bladder. When a stone blocks the ureter, it causes severe pain called renal colic.

Types of stones

• Calcium oxalate stones: the most common type
• Calcium phosphate stones
• Uric acid stones, more common with gout, diabetes, or a diet high in animal protein
• Struvite stones, linked to certain urinary infections
• Cystine stones, from a rare inherited condition

Common symptoms

• Severe pain in the side, back, or lower belly that comes in waves
• Pain spreading to the groin
• Blood in the urine, which may look pink, red, or brown
• Nausea and vomiting
• Needing to urinate often or urgently

Risk factors

• Not drinking enough fluids
• Diets high in salt or animal protein
• Obesity and diabetes
• A past stone or family history
• Some bowel conditions and surgeries
• Some medications and supplements

Passing a stone

Pain control

NSAIDs, such as ibuprofen, naproxen, or ketorolac, are often the first choice for kidney stone pain, as long as your kidneys work well and NSAIDs are safe for you. Acetaminophen and, for short periods, other medications may also be used. Your clinician will advise what fits your health.

Will it pass on its own?

Size and location matter most. Stones smaller than about 5 mm usually pass on their own, often within a few weeks [4]. Stones closer to the bladder are more likely to pass. Larger stones are less likely to pass without help.

Medical expulsive therapy

Alpha blockers, such as tamsulosin, relax the muscle of the ureter. They have been widely used to help stones pass. The SUSPEND trial tested this in more than 1,100 adults with stones in the ureter [2]. After 4 weeks, about 80 percent of people did not need a procedure to clear the stone, whether they took tamsulosin, nifedipine, or a placebo [2]. Most stones in that trial were small. Other analyses suggest tamsulosin may help more with stones between about 5 and 10 mm. Your clinician will weigh this based on your stone.

When a procedure is needed

A procedure is often considered if [3]:

• The stone is large or not moving
• Pain cannot be controlled
• There are signs of infection
• The kidney is badly blocked or kidney function is worsening

Common procedures include:

• Ureteroscopy: a thin scope passed through the bladder into the ureter to remove or break up the stone with a laser
• Shock wave lithotripsy: sound waves from outside the body that break the stone into small pieces
• Percutaneous nephrolithotomy: a procedure through a small cut in the back for large kidney stones

What your doctor looks at

Tests after a first stone

The American Urological Association (AUA) guideline recommends that clinicians [1]:

• Take a diet and medical history
• Order blood tests, including kidney function, calcium, and uric acid
• Check a urine test
• Analyze the stone if it is caught

24-hour urine test

For people at high risk, or who have had more than one stone, the AUA recommends a 24-hour urine collection [1]. It measures volume, calcium, oxalate, citrate, uric acid, sodium, and other factors. This shows what is driving stone formation and guides prevention.

Prevention recommendations

Key AUA recommendations include [1]:

• Drink enough fluid to make at least 2.5 litres (about 10 cups) of urine a day.
• Limit sodium if you form calcium stones and have high urine calcium.
• Keep normal dietary calcium, about 1,000 to 1,200 mg a day. Cutting calcium can raise stone risk.
• Limit oxalate-rich foods, such as spinach, rhubarb, and nuts, if you have calcium oxalate stones and high urine oxalate.
• Limit animal protein if you form calcium or uric acid stones.
• Eat more fruits and vegetables if urine citrate is low.

Medications for prevention

If diet changes are not enough, the AUA recommends medication based on the 24-hour urine test [1]:

• Thiazide diuretics for high urine calcium with recurrent calcium stones
• Potassium citrate for low urine citrate, or to make urine less acidic for uric acid and cystine stones
• Allopurinol for some people with high urine uric acid and calcium oxalate stones

Canada and US notes

Canadian urologists use similar principles, and the Canadian Urological Association has published guidance on stone management. Access to 24-hour urine testing and stone analysis can differ between provinces and US health plans.

Questions to ask your clinician

• How big is my stone, and where is it?
• How likely is it to pass on its own, and how long should I wait?
• Would tamsulosin help in my case?
• What pain medication is safe for me?
• Do I need a procedure, and which type?
• Should I have a 24-hour urine test?
• What should I change in my diet for my stone type?

When to get care quickly

Call 911 or go to the emergency department if you have:

• Fever or chills with stone pain, which can mean an infected, blocked kidney
• Pain so severe you cannot get comfortable or keep fluids down
• Very little or no urine
• Heavy bleeding or clots in your urine
• Stone symptoms and only one working kidney, a kidney transplant, or pregnancy

Bottom line

Most small kidney stones pass on their own with time and pain control. Fever or chills with a stone is an emergency. After a stone, drinking enough fluid, limiting salt and animal protein, and keeping normal calcium can lower your risk of another one. A 24-hour urine test and stone analysis help guide prevention.

Primary AI can show you the guideline and study sources behind this topic in plain language, so you can bring better questions to your appointment.