What Causes Kidney Stones?

Kidney stones are solid deposits that form in the kidneys when you have high levels of certain minerals in your urine, such as calcium and uric acid. This can happen when an excess amount of waste in your urine crystallizes (begins to form crystals) and slowly develops into stones. You can develop kidney stones for a variety of reasons, including eating certain diets or taking some medications.

Researchers estimate that 6% to 11% of the U.S. population develop kidney stones at some point in their lifetime. That's why knowing the risk factors and causes of the condition can sometimes help you prevent kidney stones and understand when you should seek attention from a healthcare provider.

Diet

Certain diets, like those high in sodium (salt) and animal meat, may increase your risk of developing kidney stones. Eating an excess amount of animal meat can increase the amount of acid in your urine, paving the way for kidney stones to form. Additionally, having too much calcium in your urine is a leading cause of kidney stones. High-sodium diets can prevent your urine from reabsorbing calcium which can lead to an overflow of calcium in your urine and increase your risk of developing stones.

It’s important to note that you can't reduce the amount of calcium in your urine by cutting down on dietary calcium. In fact, dietary calcium (such as the mineral found in milk or yogurt) is not a direct cause of excess calcium and you need a sufficient amount of calcium in your diet to maintain bone health. Instead, experts agree that reducing your intake of animal protein and sodium, while maintaining your consumption of dietary calcium and water can lower your risk of kidney stones. 

Low Urine Volume

Sometimes, kidney stones can form when you don't have enough urine in your body. When there is a low amount of urine in your kidneys, that urine can become concentrated in minerals. If this happens, you may be at an increased risk of developing stones. There are a few reasons why you may have low urine volume, including:

• Not drinking the recommended amount of water for your body weight
• Experiencing dehydration from environmental causes or medical conditions
• Exercising without replenishing your fluids and drinking enough water

Medical Conditions

Some medical conditions, both related and unrelated to the urinary tract, can increase your risk for kidney stones. Kidney diseases and recurrent urinary tract infections (UTIs) are common culprits of kidney stones. However, other health conditions can also increase your risk, such as:

• Inflammatory bowel disease
• Hyperparathyroidism
• Gout
• Obesity

Medications

Certain prescription and over-the-counter medications can increase your chances of forming kidney stones. These include:

• Diuretics (water pills)
• Calcium antacids
• Vitamin C supplements
• Topamax (topiramate)—a medication for epilepsy
• Medications for high blood pressure such as calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors, and angiotensin II receptor blockers (ARBs)

Are Kidney Stones Hereditary? 

Research suggests that having a sibling or parent with kidney stones increases your likelihood of developing kidney stones, too. But, there is still much left unknown about the hereditary or genetic nature of kidney stones. 

Here's what experts know so far: cystine kidney stones are the least common type of stones, but they are also the most common type that people inherit from their parents. Specifically, these kidney stones can develop as a result of a rare genetic disorder known as cystinuria, which causes stones due to a build-up of a protein called cystine. If both of your parents have the genes that can cause cystinuria (SLC3A1 and SLC7A9), you may be at an increased risk of developing stones. 

Who Gets Kidney Stones? 

While drinking plenty of water, eating a balanced diet, and treating any underlying conditions can help you lower your risk of experiencing kidney stones, you can sometimes develop kidney stones for reasons out of your control. These include:

• Age: The older you are, the more likely you are to get a kidney stone. Generally, people over the age of 60 have a higher risk of developing stones in comparison to younger adults. Those assigned male at birth and are 80 years or older are at the highest risk of having kidney stones. 
• Sex: Kidney stones are common in both sexes. Historically, males have had more cases of kidney stones. But, recent studies show similar rates of kidney stones among males and females. Research estimates that 6% of females and 11% of males in the U.S. may form kidney stones at least once in their lifetime. 
  
• Pregnant people: Those who are pregnant may be more likely to develop kidney stones during their second or third trimester.

A Quick Review 

Kidney stones form when certain minerals (like calcium and uric acid) found naturally in your urine reach high enough levels and become hardened. You might develop kidney stones for several reasons, including eating a high-sodium diet, having a low urine volume, or living with certain health conditions such as recurrent UTIs. Some research also shows that certain types of kidney stones may be genetic. You may also be at an increased risk of developing stones if you are over 60 years old and were assigned male at birth.