Kidney stones (also called renal calculi, nephrolithiasis, or urolithiasis) are hard deposits made of minerals and salts that form inside your kidneys.
Kidney stones in the urinary tract are formed in several ways. Calcium can combine with chemicals, such as oxalate or phosphorous, in the urine. This can happen if these substances become so concentrated that they solidify. Kidney stones can also be caused by a buildup of uric acid. The uric acid buildup is caused by the metabolism of protein. Your urinary tract wasn’t designed to expel solid matter, so it’s no surprise that kidney stones are very painful to pass. Luckily, they can usually be avoided through diet.
Symptoms
A kidney stone usually will not cause symptoms until it moves around within your kidney or passes into your ureters — the tubes connecting the kidneys and the bladder. If it becomes lodged in the ureters, it may block the flow of urine and cause the kidney to swell and the ureter to spasm, which can be very painful. At that point, you may experience these signs and symptoms:
- Severe, sharp pain in the side and back, below the ribs
- Pain that radiates to the lower abdomen and groin
- Pain that comes in waves and fluctuates in intensity
- Pain or burning sensation while urinating
Other signs and symptoms may include:
- Pink, red, or brown urine
- Cloudy or foul-smelling urine
- A persistent need to urinate, urinating more often than usual or urinating in small amounts
- Nausea and vomiting
- Fever and chills if an infection is present
Pain caused by a kidney stone may change — for instance, shifting to a different location or increasing in intensity — as the stone moves through your urinary tract.
Causes
Kidney stones often have no definite, single cause, although several factors may increase your risk.
Kidney stones form when your urine contains more crystal-forming substances — such as calcium, oxalate, and uric acid — than the fluid in your urine can dilute. At the same time, your urine may lack substances that prevent crystals from sticking together, creating an ideal environment for kidney stones to form.
Diet, excess body weight, some medical conditions, and certain supplements and medications are among the many causes of kidney stones. Kidney stones can affect any part of your urinary tract — from your kidneys to your bladder. Often, stones form when the urine becomes concentrated, allowing minerals to crystallize and stick together.
Passing kidney stones can be quite painful, but the stones usually cause no permanent damage if they’re recognized in a timely fashion. Depending on your situation, you may need nothing more than to take pain medication and drink lots of water to pass a kidney stone. In other instances — for example, if stones become lodged in the urinary tract, are associated with a urinary infection, or cause complications — surgery may be needed.
Your doctor may recommend preventive treatment to reduce your risk of recurrent kidney stones if you’re at increased risk of developing them again.
Types of kidney stones
Knowing the type of kidney stone you have helps determine its cause, and may give clues on how to reduce your risk of getting more kidney stones. If possible, try to save your kidney stone if you pass one so that you can bring it to your doctor for analysis.
Types of kidney stones include:
- Calcium stones: Most kidney stones are calcium stones, usually in the form of calcium oxalate. Oxalate is a substance made daily by your liver or absorbed from your diet. Certain fruits and vegetables, as well as nuts and chocolate, have high oxalate content. Dietary factors, high doses of vitamin D, intestinal bypass surgery, and several metabolic disorders can increase the concentration of calcium or oxalate in urine. Calcium stones may also occur in the form of calcium phosphate. This type of stone is more common in metabolic conditions, such as renal tubular acidosis. It may also be associated with certain medications used to treat migraines or seizures, such as topiramate (Topamax, Trokendi XR, Qudexy XR).
- Struvite stones: Struvite stones form in response to a urinary tract infection. These stones can grow quickly and become quite large, sometimes with few symptoms or little warning.
- Uric acid stones: Uric acid stones can form in people who lose too much fluid because of chronic diarrhea or malabsorption, those who eat a high-protein diet, and those with diabetes or metabolic syndrome. Certain genetic factors also may increase your risk of uric acid stones.
- Cystine stones: These stones form in people with a hereditary disorder called cystinuria that causes the kidneys to excrete too much specific amino acid.
Risk factors
Factors that increase your risk of developing kidney stones include:
- Family or personal history: If someone in your family has had kidney stones, you’re more likely to develop stones, too. If you’ve already had one or more kidney stones, you’re at increased risk of developing another.
- Dehydration: Not drinking enough water each day can increase your risk of kidney stones. People who live in warm, dry climates and those who sweat a lot may be at higher risk than others.
- Certain diets: Eating a diet that’s high in protein, sodium (salt), and sugar may increase your risk of some types of kidney stones. This is especially true with a high-sodium diet. Too much salt in your diet increases the amount of calcium your kidneys must filter and significantly increases your risk of kidney stones.
- Obesity: High body mass index (BMI), large waist size, and weight gain have been linked to an increased risk of kidney stones.
- Digestive diseases and surgery: Gastric bypass surgery, inflammatory bowel disease, or chronic diarrhea can cause changes in the digestive process that affect your absorption of calcium and water, increasing the amounts of stone-forming substances in your urine.
- Other medical conditions such as renal tubular acidosis, cystinuria, hyperparathyroidism, and repeated urinary tract infections also can increase your risk of kidney stones.
- Certain supplements and medications, such as vitamin C, dietary supplements, laxatives (when used excessively), calcium-based antacids, and certain medications used to treat migraines or depression, can increase your risk of kidney stones.
Remedies
What to eat and drink?
If you’re trying to avoid kidney stones, what you eat and drink is as important as what you shouldn’t eat and drink. Here are some important rules of thumb to keep in mind.
Stay hydrated
Fluids, especially water, help to dilute the chemicals that form stones. Try to drink at least 12 glasses of water a day.
Up your citrus intake
Citrus fruit, and their juice, can help reduce or block the formation of stones due to naturally occurring citrate. Good sources of citrus include lemons, oranges, and grapefruit.
Eat lots of calcium (and vitamin D).
If your calcium intake is low, oxalate levels may rise. It’s preferable to get your calcium from food, rather than from supplements, as these have been linked to kidney stone formation. Good sources of calcium include milk, yogurt, cottage cheese, and other types of cheeses.
Vegetarian sources of calcium include legumes, calcium-set tofu, dark green vegetables, nuts, seeds, and blackstrap molasses. If you don’t like the taste of cow’s milk, or, if it doesn’t agree with you, try lactose-free milk, fortified soy milk, or goat’s milk.
Also, make sure to include foods high in vitamin D each day. Vitamin D helps the body absorb more calcium. Many foods are fortified with this vitamin. It’s also found in fatty fishes, such as salmon, egg yolks, and cheese.
14 best fruits for kidney stones
Cleanse Your Kidneys Naturally | 14 Best Fruits for Kidney Stones
Eating a diet rich in antioxidants, vitamins, and other nutrients can help promote kidney health.
If you have kidney disease, a variety of fruits can be beneficial to include in your diet as long as they don’t contain excessive amounts of potassium and phosphorus.
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Strawberries
- Contain two types of phenols, anthocyanins, and ellagitannins, which improve kidney function.
- Rich in antioxidants, which help protect the body from oxidative damage.
- Great source of vitamin C, manganese, and fiber.
- Contain anticancer and anti-inflammatory properties that promote overall good health.
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Cranberries
- Loaded with anti-inflammatory and antibacterial properties, which are beneficial for people suffering from kidney ailments or UTIs.
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Blueberries
- 1 cup of blueberries contains 114 grams of potassium and 18 milligrams of phosphorus.
- High in antioxidants and phytonutrients called anthocyanidins, which reduce inflammation and promote renal and kidney health.
- Good source of vitamin C and manganese, which are good for bones and skin and help reduce signs of aging.
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Raspberries
- Enriched with phytonutrients called ellagic acid, which help neutralize free radicals in the body and prevent cell damage.
- Contain flavonoids, which are good for improving kidney function and can reduce the growth of cancer cells.
- Excellent source of manganese, vitamin B and C, fiber, and folate.
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Apples
- 1 medium-sized apple has 195 milligrams of potassium and 20 milligrams of phosphorus.
- May help lower cholesterol and blood sugar levels and ease constipation.
- Anti-inflammatory properties and high fiber content, help improve kidney function.
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Grapes
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Pineapples
- Low-potassium food option that helps lower blood pressure, which is a common complication of severe kidney disease.
- Contains bromelain, a digestive enzyme that helps dissolve kidney stones in the body.
- High in fiber and supports heart health (heart complications are common in people undergoing dialysis).
- Good source of vitamin C boost, which helps boost the immune system.
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Citrus fruits
The more vitamin C in your diet, the better for your kidneys. Oranges, lemons, and other citrus fruits contain vitamin C in abundance. Consuming dilute lemon juice daily may help decrease the risk of kidney stone formation.
Other fruits that may be recommended for promoting kidney health include:
- Pears
- Peaches
- Clementines
- Nectarines
- Mandarins
- Plums
- Satsumas
- Watermelon
- Cherries