Causes and Risk Factors for Kidney Stones (Nephrolithiasis)

Overview

Kidney stones are hard deposits made of minerals and salts that form in the kidneys and can cause pain, nausea, and difficulty urinating as they pass through the urinary tract. Kidney stones are caused by several factors, including:

High levels of calcium, oxalate, and phosphorus in the urine: These minerals are normally found in urine and do not cause problems at low levels. However, when they are present in high amounts, they can crystallize and form kidney stones.
Certain foods: Some foods may increase the chances of developing kidney stones in individuals who are more prone to them. Examples include a diet high in animal proteins or salt, as well as consuming too much salt, sugar, fructose, and animal proteins.
Medical conditions: Certain medical conditions can increase the risk of kidney stones. These include obesity, bowel inflammation, cystic kidney disease, UTIs (urinary tract infections), hyperuricosuria (elevated levels of uric acid in urine), and gout.
Medications: Taking certain medications can also increase the risk of kidney stones. Examples include diuretics (medications that increase urine production) and calcium-based antacids.
Dehydration: When people do not drink enough fluids, they become dehydrated, which can lead to the formation of kidney stones. Dehydration causes the urine to contain less water and more minerals and compounds, which can transform into stones.

It's important to note that there are different types of kidney stones, with calcium oxalate or calcium phosphate stones being the most common. Additionally, individuals with a personal or family history of kidney stones may be more prone to developing them.

Non-modifiable Risk Factors (Risk Factors You Can't Change)

Non-modifiable risk factors for Kidney Stones cannot be controlled or changed. They are as follows:

Age: As individuals get older, their risk of developing kidney stones increases. This is because the kidneys may not function as efficiently as they did when they were younger, leading to a higher chance of stone formation.
Sex assigned at birth: While anyone can develop kidney stones, certain studies suggest that men are more prone to developing them compared to women. This could be due to differences in urinary tract anatomy or hormonal factors.
Genetics: Family history plays a role in kidney stone formation. If someone has a close relative who has had kidney stones, their own risk may be higher. Genetic factors can influence the way the body processes and excretes certain substances that can contribute to stone formation.
Race or ethnicity: Some studies have found that certain racial or ethnic groups, such as Indigenous people, have a higher prevalence of kidney stones. However, more research is needed to fully understand the underlying reasons for these disparities.

It's important to note that non-modifiable risk factors cannot be changed or controlled. However, being aware of these risk factors can help individuals and healthcare providers take proactive measures to monitor and manage kidney stone risk.

Modifiable Risk Factors (Factors You May Be Able to Change)

Kidney stones can be influenced by certain factors that are modifiable, meaning they can be changed or controlled. Here are some modifiable risk factors for kidney stones:

Obesity: Being overweight or obese increases the risk of kidney stones. Obesity is typically defined as having a body mass index (BMI) of 30 or higher.
Hypertension: High blood pressure, also known as hypertension, is a risk factor for kidney stones. Hypertension is usually diagnosed when blood pressure consistently measures 130/80 mmHg or higher.
Type 2 Diabetes: People with type 2 diabetes have a higher risk of developing kidney stones. Type 2 diabetes is a chronic condition characterized by high blood sugar levels.
Diet: Certain dietary factors can contribute to kidney stone formation. These include consuming a high amount of sodium (salt), oxalate-rich foods (such as spinach and rhubarb), and animal protein (such as red meat).
Lifestyle: Unhealthy lifestyle habits, such as lack of physical activity and excessive alcohol consumption, can increase the risk of kidney stones.
Blood and urine minerals: Imbalances in minerals in the blood and urine can contribute to kidney stone formation. For example, high levels of calcium or uric acid in the urine can increase the risk.

Reducing Risks

There are several actions a person can take to modify their risk factors and prevent or reduce the chances of getting kidney stones. Here are some key steps to consider:

Stay hydrated: Drinking plenty of water is one of the best ways to prevent kidney stones. When you stay hydrated, your urine contains more fluid, making it less likely for minerals and salts to cluster together and form stones. It is recommended to drink between six and eight 8-ounce glasses of water per day.
Reduce salt intake: Sodium, or salt, can cause water retention and lead to dehydration. By reducing your salt intake, you can help lower your risk of kidney stones. Be mindful of the amount of salt in your diet and try to limit your consumption of salty foods.
Maintain a moderate weight: Being overweight or obese can increase the risk of developing kidney stones. By maintaining a healthy weight through regular physical activity and a balanced diet, you can help reduce this risk.
Quit smoking: Smoking is not only harmful to your overall health but can also increase the risk of kidney stones. If you smoke, quitting can have multiple health benefits, including reducing the likelihood of developing kidney stones.
Manage existing conditions: Certain medical conditions such as hypertension (high blood pressure) and diabetes can increase the risk of kidney stones. It is important to work with your healthcare provider to manage these conditions effectively through medication, lifestyle changes, and regular check-ups.
Avoid long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs): NSAIDs, such as ibuprofen or naproxen, are commonly used for pain relief but prolonged use can increase the risk of kidney stones. It is advisable to consult with your doctor before using these medications long-term.
Dietary modifications based on stone type: Depending on the type of kidney stone a person has experienced in the past or is prone to developing, specific dietary modifications may be recommended:
- For calcium oxalate stones: Reduce or avoid consumption of foods high in oxalate such as nuts (e.g., peanuts), rhubarb, and spinach. Limit sodium intake and consider increasing calcium intake through fortified foods like cereals and bread.
- For calcium phosphate stones: Consume foods low in sodium and limit animal protein intake while increasing calcium intake.
- For uric acid stones: Reduce animal protein consumption and consider switching to plant-based protein sources like legumes and soy foods.

It's important to note that while these actions may help reduce the risk of kidney stones, they are not foolproof methods. It's always a good idea to consult with your healthcare provider for personalized advice based on your specific health needs and medical history.