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Kidney Stones: Symptoms, Risk Factors, and Treatment for Nephrolithiasis

Kidney stones are among the more painful conditions that people experience. Understanding the nature of kidney stones, what causes them, and their symptoms can help you be armed to prevent them or treat them if necessary.

Kidney stones are hard deposits of salts or minerals that form in one or both kidneys. Kidney stones are typically excreted through urine, although sometimes they are surgically removed. The natural removal process can range from a few days to a few weeks.

The development of kidney stones is called renal lithiasis or nephrolithiasis. One study estimates that 9 percent of women and 19 percent of men in the United States develop kidney stones at least once in their life. People between the ages of 30 and 60 are affected by kidney stones more often than older or younger people.

Calcium stones are the most common type of kidney stone and can be made up of two compounds: calcium oxalate or calcium phosphate.

Calcium oxalate is found in up to 80 percent of kidney stones. Stones made of calcium oxalate form on something called a Randall’s plaque, a microscopic deposit of calcium phosphate in the kidneys. Because Randall’s plaques are made of calcium phosphate, this explains why a small amount of calcium phosphate is found in mainly calcium oxalate stones. Oxalate stones also can contain uric acid. Calcium oxalate stones are more common in people with some metabolic conditions and in people who get migraines.

Calcium phosphate stones are found in conjunction with oxalate or struvite, which causes struvite stones. About 15 percent of kidney stones are made of calcium phosphate. The two common types of calcium phosphate are apatite (more common) and brushite (less common).

Struvite stones are formed in the upper urinary tract only when certain bacteria are present. About 1 percent of kidney stones are struvite stones. They form in response to an infection and are more common in women, likely because of the higher incidence of urinary tract infections in women. These stones can become large and sometimes grow without symptoms.

Uric acid stones contain a form of urate such as sodium urate or ammonium urate. About 8 percent of kidney stones are uric acid stones, and they sometimes contain calcium oxalate as well. People with gout or a low fluid intake are especially susceptible to this type of kidney stone, as are people with rapid fluid loss or who consume large amounts of protein.

Cystine stones are formed in people with a genetic disorder that causes an amino acid called cysteine to build up in the urine. This condition is called cystinuria. DHA (2,8-dihydroxyadenine) crystals are made up of dihydroxyadenine and form as a result of adenine phosphoribosyltransferase deficiency.

One of the primary signs of kidney stones is pain during urination, usually in the lower abdomen and groin. Pain in the back and sides of the torso is also common, but discomfort isn’t the only sign of a kidney stone. Other symptoms of kidney stones include:

  • Urine with pink, red, or brown tints
  • Urine that is cloudy or has a bad smell
  • The continual need to urinate 
  • Nausea or vomiting
  • Urinating small amounts or not at all

Kidney stones can be caused by urinary problems such as concentrated urine. Dark-colored urine has less water and is more concentrated, which makes it easier for minerals to crystallize. Dehydration can lead to concentrated urine.

Consuming vitamin C can make your body produce oxalate, which is a component of some calcium kidney stones. Protein, sugar, and salt can also contribute to kidney stone development. A high-sodium diet increases the amount of calcium in your body and contributes to kidney stones.

Human immunodeficiency virus and the drugs used to treat it, called antiretroviral therapies, can also increase the risk of kidney stones.

The risk factors for each type of kidney stone overlap in many ways. For example, a low urine volume and high amounts of uric acid, calcium, or phosphate excretion can increase your risk of developing a stone.

For calcium oxalate crystals, high oxalate excretion and low citrate excretion can be risk factors. Undergoing intestinal bypass surgery can also increase oxalate in urine and the risk of nephrolithiasis. The risk factors for calcium phosphate crystals include a high urinary pH, high urine calcium excretion, and lower citrate excretion. People with a low urinary pH are more at risk of developing uric acid crystals.

A low urine volume and high amounts of uric acid, calcium, or phosphate excretion can increase your risk of developing a stone.

Being genetically predisposed to kidney stones increases your chance of developing them in your lifetime. If you’ve had a kidney stone once in your lifetime, your chance of getting another is also higher. People who have had a stone at some point have a 50 percent chance of getting another in the next five years, and that chance increases as you approach 10 years since your last stone.

Numerous other conditions can increase your chance of nephrolithiasis, including preexisting renal and ureter diseases like renal tubular acidosis and cystinuria. Inflammatory bowel disease and chronic diabetes interfere with digestion and the absorption of minerals and water. This can increase the amount of substances that cause nephrolithiasis in your urine. People with type 2 diabetes often have very acidic urine, another contributing factor to kidney stones. And while not a disease, obesity has also been linked to the formation of kidney stones.

Treating nephrolithiasis is done in one of two ways: by treating the symptoms and aiding the stone’s passage or by performing surgery. Most people don’t require surgery and pass the stone on their own with lots of fluids and medication to manage the pain.

About 10–20 percent of people need surgery to remove a kidney stone. This may occur because the stone is too large to pass or has grown large and could cause damage to the kidneys or urinary tract. Struvite stones, for example, often grow large and can become infected. In such cases, minimally invasive surgeries are considered before open renal or ureteral operations.

Most people don’t require surgery and pass the stone on their own with lots of fluids and medication to manage the pain.

The most common types of surgery for removing kidney stones are percutaneous nephrolithotomy (PNL), ureteroscopy, and shock wave lithotripsy (SWL). These surgeries are safer and less expensive than more serious surgeries. Small ureteral stones can be removed by ureteroscopy or broken by SWL, which is also used on small renal stones. For larger renal stones, a physician may opt to perform a PNL.

In addition to treating the stones themselves, physicians work to treat the underlying cause of nephrolithiasis with lifestyle changes and medications. A doctor may prescribe a medication that treats high amounts of acid or calcium excretion or one that increases the amount of citrate removed from the body. Such treatments can help with remission of nephrolithiasis and a reduction in the rate of recurring stones. It is also very important to stay hydrated and maintain a healthy diet to decrease the chances of getting kidney stones.

Most people don’t hesitate to see a doctor when they experience unusual pain, but others may be tempted to wait it out. While this can be an effective solution for kidney stones, the possibility of infection or internal injury means you should still consult your doctor.

If the pain becomes unbearable, if it’s accompanied by nausea or vomiting, or if you show signs of an infection, you should seek medical help. Other signs of an internal issue include blood in your urine. Even if the stone passes naturally and without complications, a doctor can work with you to prevent future kidney stones.

The most effective way to prevent kidney stones is to stay hydrated. Dehydration increases your risk of kidney stones, and people who live in a warm climate or who sweat a lot are more likely to become dehydrated.

Drinking about 10 cups of water per day can keep stones from returning. Coffee and tea also count towards your water intake, but lemon water is an even better option. Lemons contain citrate, and increasing citrate levels reduces the formation of stones.

Educating yourself on preventive measures and risk factors for kidney stones may help you avoid them or treat them if needed.






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