Kidney stones (nephrolithiasis or urolithiasis) are hard objects formed from materials in the urine. Usually, waste products dissolve in urine, but if there is excess waste and insufficient liquid, sometimes crystals can form into solids that grow. Small stones may pass out of the body in the urine, but larger stones too big to pass can block urine flow in the kidney, ureter, bladder, or urethra, causing the pain of kidney stones.
Certain diets can reduce the risk of kidney stones. The Dietary Approaches to Stop Hypertension (DASH) diet has been shown in studies to reduce the risk of kidney stones. The DASH plan recommends the best foods to eat include:
- Vegetables, fruits, and whole grains
- Fat-free or low-fat dairy products
- Fish, poultry
- Beans, nuts, and vegetable oils
- Foods low in saturated and trans fats
- Foods rich in potassium, calcium, magnesium, fiber, and protein
- Foods lower in sodium
- Limit:
If you already had kidney stones, changes in your diet depend on which type you had.
- For calcium oxalate stones, calcium phosphate stones, and uric acid stones:
- For protein, the best foods to eat include:
- Beans
- Dried peas
- Lentils
- For calcium, the best foods to eat include:
- Calcium-fortified juices
- Cereals
- Breads
- Certain vegetables
- Some types of beans
- Reduce sodium
- Limit animal protein, including:
- Beef, chicken, and pork, especially organ meats
- Eggs
- Fish and shellfish
- Milk, cheese, and other dairy products
In addition to the above, diet changes for calcium oxalate stones include:
- Avoid foods that are sources of oxalate:
- Nuts and nut products
- Peanuts (which are legumes)
- Rhubarb
- Spinach
- Wheat bran
Diet changes for calcium phosphate stones also include:
- For protein, the best foods to eat include:
- Soy foods, such as soy milk, soy nut butter, and tofu
- Nuts and nut products, such as almonds and almond butter, cashews and cashew butter, walnuts, and pistachios
- Sunflower seeds
The most important diet change for cystine stones is drinking plenty of liquids, primarily water.
What Are Symptoms of Kidney Stones?
Kidney stones may not cause any symptoms. When symptoms do occur, they may include:
- Pain
- Varies from a mild to so intense it requires hospitalization
- Waves of severe pain (renal colic) that can last up to an hour
- Occurs in the side, between the ribs and the hip (the flank) or the lower abdomen, and can shift toward the groin
- Pain can also be vague or feel like a stomach ache that doesn’t go away
- Blood in the urine (hematuria)
- Urine may appear pink or reddish
- Blood may not be visible but is seen when urine is examined under a microscope
- Gravel
- Passage of “gravel” or “sand,” which are multiple small stones in the urine
- Pain with urination
- Urinary urgency
- Urine that smells bad
- Cloudy appearance to urine
- Fever
- Chills
- Nausea
- Vomiting
See a doctor right away if you think you have a kidney stone. Drinking additional fluids to try to flush a stone out in the urine may be recommended. If you pass a stone, it is helpful to strain it and bring it to your doctor to determine the type of stone. Knowing the type of stone can help determine the proper treatment.
What Causes Kidney Stones?
Causes of kidney stones include:
- Diet
- Inadequate fluid consumption
- Eating foods with too much salt or sugar (especially fructose, like table sugar and high fructose corn syrup)
- Diets low in calcium
- Use of calcium supplements
- Diets high in animal proteins
- Diet with low levels of phytate (found in wheat, rice, rye, barley, and bean products)
- Frequent spinach consumption
- Obesity
- Too much or too little exercise
- Weight loss surgery
- Infections
- Family history of kidney stones
- Certain medical conditions
- Crohn's disease
- Diabetes mellitus
- Gout
- Primary hyperparathyroidism
How Are Kidney Stones Diagnosed?
Kidney stones are diagnosed based upon a patient’s symptoms and physical examination, along with testing to confirm a stone or rule out other conditions.
Tests used to diagnose kidney stones include:
- Imaging tests
- Computed tomography (CT) scan
- KUB x-ray (kidney-ureter-bladder X-ray)
- Ultrasound
- Blood tests
- Basic metabolic profile (BMP) which includes kidney function tests blood urea nitrogen (BUN) and creatinine
- Calcium
- Phosphorus
- Uric acid
- Pregnancy test
- Urine tests
- Urinalysis
- 24-hour urine test
After the stone exits the body, either on its own or following surgical removal, it can be analyzed to determine the type of stone and treatment.
What Is the Treatment for Kidney Stones?
Treatment of a kidney stone depends on the size and location of the stone, the type of stone, and the patient’s pain levels.
Home treatment may be sufficient if the stone is believed to be small enough to pass, the patient’s pain is tolerable, and they can eat and drink.
Home treatment for kidney stones includes:
- Pain management
- Medications to facilitate stone passage
- Straining urine to retrieve the stone for testing once it passes
- Knowing the type of stone you have helps determine treatment to prevent future stones
Medical treatments for larger stones or severe symptoms include:
- Stronger prescription pain medications
- Intravenous (IV) fluids given in the hospital
- Stones larger than 9 or 10 millimeters usually do not pass on their own so a procedure is needed to break up or remove the stone
- Ureteroscopy
- Shock wave lithotripsy (SWL)
- Percutaneous nephrolithotomy (PNL)
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https://www.kidney.org/atoz/content/kidneystones
https://www.kidney.org/news/kidneyCare/winter09/KidneyStoneSymptoms
https://www.niddk.nih.gov/health-information/urologic-diseases/kidney-stones/eating-diet-nutrition
https://www.nhlbi.nih.gov/health-topics/dash-eating-plan