What causes kidney stones? 7 risk factors you should know

Kidney stones can form without a person realising it until a stone moves through the urinary tract and causes severe pain. Although not drinking enough water can increase the risk, kidney stones can also develop because of certain medical conditions, inherited factors, dietary habits and medicines.

According to the US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), kidney stones are hard deposits that form when certain minerals and other substances in urine become concentrated enough to form crystals.

The crystals can stick together and grow into stones. Their size varies, and while some pass out of the body without causing serious problems, others can block the flow of urine and require medical treatment.

Here are seven factors that can cause or increase the risk of kidney stones.

Try drinking a glass of water frequently [123RF]

Dehydration is an important risk factor for kidney stones. When a person does not drink enough fluids, less water is available to dilute substances in urine that can form crystals.

This can be a concern for people who sweat heavily, exercise frequently or lose fluids through prolonged diarrhoea.

Drinking enough water throughout the day can help lower the risk. However, the amount of fluid a person needs depends on factors such as their activity level, climate and health. Anyone who has been advised to restrict fluids because of a medical condition should follow their healthcare professional’s advice.

Too much salt can be harmful [TimesofIndia]

A high-sodium diet can increase the risk of certain kidney stones, particularly calcium-based stones.

When a person consumes too much sodium, the kidneys may release more calcium into the urine. If the urine contains enough stone-forming substances, crystals can develop.

Salt is not found only in what people add to food during cooking. Packaged foods, processed meats, seasoning products and some sauces can also contribute to sodium intake.

Reducing excessive salt consumption may help lower the risk of developing kidney stones.

Eating a lot of animal protein, including meat, fish and shellfish, may increase the risk of some types of kidney stones.

Animal protein can affect the chemical composition of urine, including increasing uric acid levels and making urine more acidic. These changes can contribute to the formation of uric acid stones in susceptible people.

This does not mean that meat or fish must be eliminated from the diet. The appropriate amount of protein depends on a person's overall nutritional needs and, where applicable, the type of kidney stone they have developed.

Some health conditions affect how the body processes minerals and other substances, increasing their concentration in urine.

Conditions associated with a higher risk of kidney stones include:

Having one of these conditions does not mean a person will definitely develop kidney stones. It means their risk may be higher.

Having a family history of kidney stones

Genetics can play a role in kidney stone formation. People whose close relatives have had kidney stones may be more likely to develop them.

Some inherited conditions can also cause the kidneys to release unusually high amounts of particular substances into urine. One example is cystinuria, a genetic disorder that causes excessive amounts of the amino acid cystine to pass into urine, where it can form stones.

A person who has previously developed kidney stones also has a higher risk of developing them again.

Some medicines can change urine colour [iStock]

Some medicines and supplements can increase the risk of kidney stones in certain circumstances.

Examples include calcium-based antacids, some diuretics, certain medicines used to treat seizures or migraines, and high-dose vitamin C supplements.

The risk depends on the substance, dose, duration of use and individual health circumstances. Not everyone taking these products will develop kidney stones.

People should not stop prescribed medicines or discontinue medically recommended supplements without first speaking to a qualified healthcare professional.

Kidney stones can form when urine contains more crystal-forming substances than the available fluid can dilute, or when it lacks enough substances that help prevent crystals from forming and sticking together.

Knowing the type of stone a person has can help a healthcare professional identify possible causes and recommend suitable prevention measures.

Importantly, eating calcium-rich foods does not automatically cause calcium kidney stones. Adequate calcium from food can help reduce the amount of oxalate absorbed in the intestines. People who are prone to stones should not eliminate calcium from their diet without medical advice.

People who have had kidney stones more than once may benefit from medical investigations, including urine or blood tests and analysis of a passed stone, to help identify the underlying cause.

There is no single dietary rule that prevents every type of kidney stone. A healthcare professional can recommend changes based on the person's medical history and test results.

Sources: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), Mayo Clinic and the UK National Health Service (NHS).