Why do kidney stones form?

Kidney stones, also known as renal calculi, are a very common and painful condition. They are caused by the build-up and crystallisation of minerals present in the urine. They tend to occur more frequently in men than in women.  

In most cases, their development is related to health problems, certain medications or a lack of hydration. Furthermore, people who have already had stones are at greater risk of developing them again. 

Although passing them is usually quite painful, the intensity varies depending on the size, location and type of stone. Fortunately, there are effective treatments and methods to prevent them from forming. 

The most common types of kidney stones 

There are four main types of kidney stones:    

• Calcium stones. These are mainly composed of calcium oxalate. They usually occur in people whose diet is very high in this compound, due to an excess of sodium, animal proteins or certain medications.     

• Uric acid stones. These form due to the build-up of this compound in the urine. They are usually treated by reducing their levels in the body.   

• Struvite stones. These can develop following a urinary tract infection. They usually cause few symptoms at first and grow rapidly.    

• Cystine stones. These are rare and are linked to a genetic condition called cystinuria. This involves an excessive build-up of cystine in the urine, which eventually forms stones in the kidneys and bladder.

Calcium and uric acid stones are the most common. Each type requires specific treatment and prevention. Therefore, when a stone is passed, it is recommended that you keep a sample for your doctor. This will enable the doctor to determine the cause of its formation and how to prevent future occurrences. 

The most common symptoms 

Generally, symptoms do not appear until the mass begins to move. During this process, it may become lodged in one of the two ureters, which are the tubes that carry urine from the kidneys to the urethra. This blockage usually causes symptoms, including:

Main causes of kidney stones 

More than two million people in Spain have kidney stones, and 85% of these cases are linked to diet and unhealthy lifestyle habits. This is according to the Official College of Pharmacists of Valencia.   

The main cause of kidney stones is dehydration. If you do not drink enough fluids, the volume of urine decreases and the likelihood of minerals crystallising in the kidneys increases. There are also other risk factors. Some of these, mentioned by the American Key Fund, are the following:

• Family history. The risk of developing this condition increases if a family member has previously suffered from it.   

• Certain medical conditions. Kidney stones are more likely to form in people suffering from other conditions. For example, cystinuria, repeated urinary tract infections or chronic inflammation of the intestines.   

• Certain medicines and supplements. Some medicines, dietary supplements or certain laxatives can promote the formation of kidney stones.   

• A history of kidney stones. People who have had this condition more than once are more likely to suffer from it again in the future.   

You should see a doctor if... 

If you experience any symptoms of pain or discomfort, it is essential to make an appointment with a healthcare professional. In most cases, treatment usually involves waiting for the stone to pass naturally whilst drinking plenty of water and taking painkillers. However, if the stone blocks the urinary tract or causes severe pain, your doctor may recommend specific treatment to break it up or help it pass.   

If medical attention is not sought in time, complications may arise, although these are uncommon. These include severe pain, urinary and kidney infections, or loss of kidney function. Prevention is key to stopping this problem from getting worse.