Kidney stones are hard deposits made of minerals and salts that form inside the kidneys. They can be as small as a grain of sand or as large as a pebble. Stones are common, and in a hot, dry climate like Phoenix, losing fluid through sweat makes them even more likely.
Types of stones
- Calcium oxalate, the most common type
- Calcium phosphate
- Uric acid, more common in people with gout, diabetes, or a diet high in animal protein
- Struvite, linked to urinary tract infections
- Cystine, a rare inherited type
Knowing your stone type helps guide prevention, so save any stone you pass and bring it to your visit.
Risk factors
- Not drinking enough fluid, especially in hot weather
- A diet high in sodium, animal protein, or sugar
- Obesity, diabetes, gout, and some bowel conditions or surgeries
- A personal or family history of kidney stones
- Some medicines and supplements
Symptoms
A stone may cause no symptoms until it moves. Then it can cause severe pain in the side or back that may spread to the lower belly or groin, blood in the urine, nausea and vomiting, or a frequent, painful need to urinate.
Get emergency care for stone pain with fever or chills.
Also seek care right away if you cannot keep fluids down or cannot pass urine.Preventing stones from coming back
- Drink enough fluid to pass about 2.5 liters (about 85 ounces) of urine a day, unless your doctor has set a fluid limit. Pale yellow urine is a good sign. Drink more on hot days and when you exercise.
- Eat less sodium. Salt raises the amount of calcium in the urine.
- Do not cut out calcium. Getting calcium from food, with meals, helps block oxalate from being absorbed. Ask before taking calcium supplements.
- Eat moderate amounts of meat, poultry, and seafood.
- Limit high-oxalate foods such as spinach, nuts, and rhubarb only if your doctor advises it for your stone type.
- Medicines may be recommended based on your stone type and urine tests.
Evaluation
If you have had more than one stone, or a stone at a young age, a kidney specialist can look for the cause with blood tests, stone analysis, imaging, and a 24-hour urine collection. The results guide a prevention plan made for you.
Questions to ask at your visit
- What type of stone did I have?
- Do I need a 24-hour urine test?
- How much should I drink each day?
- Do I need a medicine to prevent new stones?
This guide is general education and is not a substitute for medical advice. Talk with Dr. Salim or your care team about your own situation. Informed by patient materials from the National Kidney Foundation; learn more at kidney.org.