Kidney stones

Overview of kidney stones

Kidney stones are small pieces of hard, crystallized material that form in the kidney. Another name for this common condition is renal lithiasis. Most kidney stones pass out of the body in the urine without serious problems. On occasion, a kidney stone can get stuck in the ureter — the tube connecting the kidney and bladder. This can result in potentially serious or even life-threatening complications, such as kidney infection and kidney damage. 

Find a Doctor at Dignity Health for the treatment of kidney stones, especially for emergency care.

Symptoms

Small kidney stones or kidney stones that do not move and remain in the kidney may not produce any symptoms. A small kidney stone even may pass out of the body without causing pain or other symptoms. Severe, sharp, or stabbing pain in the middle area of the lower back is the main symptom of a large kidney stone that moves out of the kidney. The pain may spread to the abdomen or groin, and symptoms do not differ between men and women. Other signs and symptoms include:

  • Sweating
  • Nausea
  • Vomiting
  • Blood in the urine
  • Difficulty or pain while urinating
  • Intense need to urinate, urinating more often 

The pain associated with kidney stones often comes on quickly and then returns in waves as the body tries to get rid of them.

Causes

Kidney stones are caused by higher than normal levels of calcium, oxalate, and phosphorus in the urine. These minerals are normal and not at all problematic at low levels. One or more kidney stones can form in one or both kidneys. They begin as tiny specks and may gradually increase in size. These higher levels of minerals can be caused by:

  • High levels of calcium in the urine can be attributed to eating a diet that is high in salt. Additionally, foods that are rich in oxalate or animal protein can raise acid levels in the body and urine, which makes it easier for kidney stones to form.
  • Low urine volume. Having a consistently low urine volume may stem from dehydration or living in a hot place, and means that there is less fluid to keep the salts in your urine dissolved.
  • Bowel conditions. Bowel conditions that cause diarrhea result in the significant loss of fluid from the body, lowering urine volume and potentially increasing oxalate levels in the urine, which promote stone growth.
  • Medical conditions can cause high calcium levels in the blood or urine. These conditions include abnormal growth of the parathyroid glands or distal renal tubular acidosis.
  • Obesity changes acid levels in the urine, which can lead to stone formation.
  • Medications. Some medications and supplements increase your risk of developing kidney stones. These include calcium and vitamin C supplements.

Types 

There are four main kinds of kidney stones: 

  • Uric acid is one of the common types of kidney stones. It stems from a high intake of foods (such as meats and fish) that have elevated concentrations of purines, a naturally-occurring chemical compound. Purine intake leads to increased production of monosodium urate, which can lead to the formation of stones. This type of stone often runs in families, meaning you may be more likely to develop uric acid stones if someone else in your family has had them.
  • Calcium oxalate is one of the most common types of kidney stones and is created when calcium and oxalate combine in the urine when there is limited fluid intake. Chronic dehydration can cause this kind of kidney stone.
  • Struvite stones are not very common and are generally caused by upper urinary tract infections.
  • Cystine stones are typically larger than other stones and are caused by a rare disorder called cystinuria. This kind of stone also tends to run in families.

Risk factors

There are certain risk factors for kidney stones. Male anatomy makes kidney stones more likely. 

If someone in your family has had a kidney stone, you are also more likely to develop one. You are additionally more at risk if you have had kidney stones before. 

Certain conditions and habits can put you at risk for kidney stones, including: 

  • Dehydration
  • Gout
  • High blood pressure
  • High-protein diet
  • Hypercalciuria, when the urine contains large amounts of calcium
  • Hyperoxaluria, when the urine contains large amounts of oxalate
  • Obesity
  • Excess consumption of caffeinated beverages such as energy drinks and coffee
  • Prolonged exposure to a hot climate or high altitudes
  • Prolonged inactivity, such as being bedridden
  • Urinary tract infection 

Certain medications can also put you at risk for developing kidney stones, including:

  • Calcium-based antacids
  • Diuretics
  • Topiramate, an anti-seizure medication

Prevention

Once you figure out the cause of your kidney stones, it will be easier to prevent them. In general, diet and medication can limit stones from forming, but there is no one approach that is best for everyone. 

Dietary changes that can help include:

  • Drinking enough fluids every day, usually around 3 liters of liquid
  • Eating less meat
  • Limiting high-sodium foods
  • Eating the recommended amount of calcium
  • Eating at least five servings of fruits and vegetables each day
  • Limiting foods high in oxalates, including spinach and almonds

The information contained in this article is meant for educational purposes only and should not replace advice from your healthcare provider.