What is a kidney stone? Symptoms, Cause, Treatments and Prevention

What are Kidney Stones?

Kidney stones, also known as renal calculi or nephrolithiasis, are solid crystals made of minerals and other constituents that form in the urinary tract and cause urinary obstruction. They vary in size and can be formed in the kidneys, ureter, bladder, and urethra, blocking urine flow. 

The size of kidney stones varies from tiny particles to several centimetres. The smaller stones pass out of the body with urine, they can cause significant pain as they pass through the urinary tract. However, larger stones require surgical procedures to be broken into smaller ones and removed. 

According to the National Kidney Foundation, the number of people with kidney stones in the United States has grown over the years. The percentage increased from 3.8% in the late 1970s to 8.8% in the late 2000s. By 2013-2014, about 10% of people had kidney stones. 

According to the Cleveland Clinic, kidney stones are most common in men in their 30s and 40s. Men have an 11% chance of getting kidney stones, while women have a 9% chance. They are also more common in non-Hispanic white people. Conditions like hypertension, diabetes, and obesity increase the risk of developing kidney stones by impairing kidney function, altering urine composition, and contributing to metabolic imbalances such as diabetes, leading to higher calcium levels or obesity affecting urine composition.

Types of Kidney Stones

Kidney stones are not only made of the same crystals. The other forms of kidney stones include:

Table:01 Types of Kidney Stones

What are Common Signs and Symptoms of Kidney Stones?

The symptoms of kidney stones usually do not appear until the stone moves down the ureter. However, kidney stones result in severe pain, known as renal colic. 

The pain can be felt on and off and is sometimes severe on the back or side of the abdomen, resulting in restlessness. Small stones can still cause pain or symptoms, depending on their location. The other symptoms of kidney stones include

• Nausea
• Vomiting
• Pain in the abdomen area
• Blood in the urine (Hematuria)
• Chills
• Fever
• Increases urinary frequency
• Foul-smelling of urine
• Excreting small amount of urine

Common Signs Based on the Location of Stone 

Kidney: The stones that are located in the kidney usually do not cause symptoms unless they disrupt the normal flow of urine or move into the ureter. The symptoms involve dull ache in the back or side and fever if kidney infection occurs.

Ureter: Stones in the ureter can cause severe pain that arises from the back to the groin. The symptoms usually involve severe, colicky pain, hematuria(blood in the urine), frequent urination, nausea and vomiting.

Bladder: Stones in the urinary bladder can cause pain and discomfort in the lower abdomen and frequent urination. The symptoms include painful urination, a frequent need to urinate, and sometimes blood in the urine, which reflects the stones in the bladder.

What are the main Causes of Kidney Stones?

Kidney stones are caused due to a combination of factors that lead to the crystallisation of substances in the urine. The formation of kidney stones is more common in people between 20- 50 age groups. The other causing factors of kidney stones include sex, age and history of renal stones. 

According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), more men are prone to develop kidney stones as compared to women. In the US, white people also have more chances of suffering from kidney stones as compared to black people. Other risk factors for kidney stones include:

• Dehydration
• Gastric surgery of Bypass
• Obesity
• Consumption of poor dietary habits (high levels of protein, salt, or glucose)
• Hyperparathyroidism
• Inflammatory bowel diseases (increase calcium absorption)
• Medications (triamterene diuretics, antiseizure drugs, and calcium-based antacids)

Role of Certain Medication in Stone Formation

Table 02: Certain medicines and their role in kidney stone formation

Are There Any Risk Factors for the Kidney Stones?

The following are the risk factors for kidney stones

Age: People of any age can have kidney stones, but they are more common in adults, especially between the ages of 30 and 60. 

Gender: Men are more likely to develop kidney stones as compared to women.

Family History: People with a family history of kidney stones are more at risk. A person may develop kidney stones if a close relative has had kidney stones.

Diet: Improper diet practice also leads to kidney stone formation. A diet high in protein, sodium, and sugar increases the risk of kidney stones. For example, excessive sodium intake increases the amount of calcium, which leads to the formation of calcium-based stones. 

The other risk factors of kidney stone formation also include

• Insufficient intake of fluids
• Eating meat and protein-rich foods.
• Taking foods rich in sodium or sugars (sucrose and fructose).
• Excess intake of vitamin C supplements.
• blockage in the urinary tract.
• stomach or intestine surgery
• Take medications, including diuretics, calcium-based antacids, and some anti seizures.
• Exceptional medical conditions.

Medical Conditions Increase the Risk of Kidney Stone 

Here are some medical conditions that result in a higher risk for kidney stones. These include:

• Gout
• Diabetes
• Osteoporosis.
• Kidney cysts.
• Cystic fibrosis.
• Parathyroid disease.
• High blood pressure.
• Primary hyperoxaluria.
• Inflammatory bowel disease (IBD)
• Hemiplegia or paraplegia (types of paralysis).
• High calcium levels in your urine (hypercalciuria).
• Cystinuria (a genetic disorder that causes the formation of cystine stones)
• Obesity (leads to higher urinary calcium excretion and changes in urine pH)

How To Diagnose Kidney Stones?

Kidney stones can be diagnosed through medical examination and a complete health history assessment. Other tests are also performed to diagnose kidney stones. Ultrasound and CT scans are preferred due to their availability, cost-effectiveness, and accuracy in identifying stones. Other diagnostic methods include

• Blood tests (to assess calcium, phosphorus, uric acid, and electrolytes)
• Blood urea nitrogen (BUN) and creatinine to assess kidney functioning
• Urinalysis (to determine the presence of crystals, bacteria, blood, and white cells)
• Previous examination of stones to determine their type

These tests are performed to determine the reason for obstruction of urine flow.

• abdominal X-rays
• intravenous pyelogram (IVP)
• retrograde pyelogram
• ultrasound of the kidney (the preferred test)
• MRI scan of the abdomen and kidneys(not typically a first-line diagnostic tool for kidney stones. 
• Abdominal CT scan

Healthcare providers should take careful precautions while performing CT scans and IVPs. The contrast dye used in the CT scan and the IVP can affect kidney function. However, in people with normal kidney function, this isn’t a concern.

How are Kidney Stones Treated?

The treatment of kidney stones depends on the type and severity of symptoms. Small kidney stones usually pass through urine, but large kidney stones require proper treatment. Treatment of kidney stones usually involves

• Hydration
• Medications
• Medical procedures

Hydration

This method is most effective in passing small stones through urine. To produce a large amount of urine, it is recommended that one drink at least 2.5 to 3 litres of fluid per day. It helps to pass the small stone with urine easily, but it is painful. Over-the-counter (OTC) medicines like ibuprofen and naproxen, with or without narcotics, are effective for this process. In severe cases, some people are also recommended to stay in the hospital and take IV fluids through veins to relieve severe pain. 

Medication 

Healthcare providers also prescribe medications to prevent stones from forming or help break down. These medicines also help to remove the particular material that is causing the stone. These types of medicines are usually prescribed for certain types of stones:

• Allopurinol (for uric acid stones)
• Antibiotics (for struvite stones)
• Diuretics (water pills)
• Phosphate solutions and sodium bicarbonate or sodium citrate (used to alter urine composition and prevent stone formation)
• Water pills (thiazide diuretics)
• Tamsulosin relaxes the ureter and helps to pass the stone 

Medical Procedure

The medical procedure involves surgery, which is required if

• The stone is too large and unable to pass through urine.
• The stone is increasing.
• The stone disrupts the normal urine flow and causes an infection or kidney damage.
• Severe and unbearable pain in the abdominal area.

The following procedures are performed to remove large stones. The surgical method depends on the location, type of stone, and size.

• Percutaneous Nephrolithotomy (PCNL)
• Ureteroscopy (URS)
• Shock Wave Lithotripsy (SWL)
• Open Surgery
• Laparoscopic Surgery

Percutaneous nephrolithotomy (PCNL)

Percutaneous nephrolithotomy(PCNL) is the most common surgery used to remove large kidney stones (larger than 2 cm in size). In this procedure, a small incision is made in the back, and a thin tube with a camera (known as a nephroscope) is inserted into the kidneys. The large stone is broken into smaller pieces with the help of ultrasonic or laser energy. This process is performed under anaesthesia, and full recovery takes place in 1-2 weeks.

Ureteroscopy (URS)

Ureteroscopy is another surgical method of removing kidney stones. In ureteroscopy, a thin flexible scope (known as a telescope) is passed through the urethra and bladder into the ureter and kidney. The stone is usually grabbed with a smaller basket or broken into smaller pieces by using a laser (holmium laser). The smaller pieces of stone are usually passed through the urine. This procedure is carried out under general anaesthesia, and full recovery takes place in a few days.

Shock Wave Lithotripsy (SWL)

Shock wave lithotripsy is a process in which high-energy shock waves are used to break the stone located in the kidneys or ureter. The stone is broken into small pieces so that it can easily pass through the urine. It is a noninvasive procedure and does not require an incision. To remove kidney stones completely, a patient requires more than one session of SWL.

This procedure is carried out under general or light sedation, and recovery can take place in a few days to a week. Shock wave lithotripsy is also known as extracorporeal shock wave lithotripsy (ESWL). For some patients, SWL could be an uncomfortable form of treatment, so painkillers are usually prescribed before surgical procedures. 

Open Surgery

Open surgery is a rare procedure for removing very large or complicated stones. In this procedure, an incision is made in the side, and the stone is surgically removed. This procedure requires a longer hospital stay for full recovery and is performed under general anaesthesia. 

Laparoscopic Surgery

Laparoscopic surgery is similar to open surgery but performed with smaller incisions using laparoscopic instruments. It is not commonly used as PCNL or URS and is less invasive than open surgery. Patients recover in shorter hospital stays, ensuring quick recovery compared to open surgery. 

Pain Management During Surgical Procedure:

Pain management is an important factor during surgery. The selection of painkillers depends on the type of procedure and the severity of the pain.

Pre-Procedure Pain Management: NSAIDs(ibuprofen, naproxen) are usually prescribed before surgical procedures for pain management. They are effective in managing mild to moderate pain. Opioids(morphine) are also prescribed in case of severe pain before the surgical process. However, they are not highly recommended due to their potential side effects. NSAIDs (non-steroidal anti-inflammatory drugs) and other pain relief methods are more commonly used for managing kidney stone pain.

Pain Management during Procedure: Depending on the procedure, local anaesthesia, general anaesthesia, and sedation are used to comfort the patient during surgery.

Post-Procedure Pain Management: NSAIDs, Opioids, antispasmodic (like oxybutynin to relieve muscle spasms) and ice packs are generally recommended for post-procedure pain management.

Can Kidney Stones Be Prevented?

Adopting specific lifestyle changes can prevent kidney stones. Proper hydration is a key preventive measure. The intake of fluids depends on the requirements of each individual. It is recommended that people drink enough fluid to urinate at least 2.5 liters of urine per day. Following these steps can help prevent the formation of kidney stones.

• Drink at least 12 glasses of water per day to prevent the formation of kidney stones.
• Diet low in sodium is recommended.
• Do not consume animal protein more than 6 to 8 ounces a day.
• Limit sugar intake.
• Consume a variety of fruits and vegetables(ginger, lemon, fruit juices) in your daily diet.
• Maintain a healthy body weight
• Do not take Vitamin C supplements more than 1000mg per day.
• Moderate the intake of oxalate-rich foods (spinach, nuts, and chocolate) to prevent the formation of kidney stones.
• If stones are related to low citrate levels, citrate juices help prevent the formation of stones.

Which Foods Cause Kidney Stone Formation?

Some specific foods, if consumed excessively, are linked to kidney stone formation. Here is a list of foods that you may need to limit or avoid to prevent kidney stone formation.

• High-protein foods and foods high in oxalates, such as spinach and nuts
• Dairy (cheese)
• beef
• pork
• chicken
• processed meats
• fast food
• frozen meals
• salty snacks

These foods should be consumed in lesser amounts because animal proteins like meat, poultry, seafood, and dairy products increase the levels of uric acid, which increases the risk of developing kidney stones.

People with kidney stones should avoid high oxalate foods because it results in the formation of oxalate kidney stones. It includes chocolate, beets, nuts, tea, spinach, swiss chard and sweet potatoes.

Cola drinks should also be avoided because they are high in phosphoric acid, which can be linked to kidney stones and other chemicals that promote kidney stone formation. Moreover, added sugar also leads to kidney stone formation. 

Syrups, sucrose, and fructose contain a high amount of sugar. Its excessive consumption should be avoided to prevent stone formation. These include brown rice syrup, corn syrup, honey, agave nectar, cane sugar, and crystallised fructose.

A purine-restricted diet is recommended for people who are already suffering from uric acid stones. Food that contains purine includes alcoholic beverages, organ meat, and red meat.

What are the Ways of Passing a Kidney Stone?

Passing a kidney stone is a painful process that usually occurs in stages that take several weeks. The stages involved in passing a kidney stone is

Stages to Pass A Kidney Stone 

These stages occur while passing a kidney stone naturally:

• Stage 1: Stone Formation and Pain Induction

Kidney stones form when certain minerals and salts in the urine become highly concentrated, which leads to crystallisation. These crystals gradually accumulate and bond together to form a stone. After a kidney stone forms, it causes cramps or spasms as the kidneys contract in an effort to pass the stone. This results in severe pain in the back or side, which may occur at random and be mild at one time and severe at another.

• Stage 2:  Migration from the Kidney to the Ureter

At this stage, the stone enters the ureter, the tube that connects the kidneys to the bladder. Depending on the size of the stone involved, this stage also leads to sensations of pain and pressure.

• Stage 3: Passage through the Ureter

Most of the pain is felt at this stage only after the stone has passed through the kidney and into the bladder. However, there could be discomfort in the bladder and a need to urinate more frequently.  Sometimes, the stone can temporarily be stuck in the opening of the tube that carries urine, called the urethra.

• Stage 4: Entry into the Bladder and Exit via the Urethra

The fourth step occurs once the stone has reached the urethra. In this phase, the patient needs to exert some pressure to expel the kidney stone with the urine through the urethral opening.

Process of Passing a Kidney Stone Naturally

Most kidney stones can be passed naturally without surgical procedures. The process usually involves:

• Hydration: Drinking plenty of water (at least 2-3 litres a day) helps flush out the urinary system, making it easier for the stone to pass.
• Physical Activity: Gentle exercise, like walking, can encourage the stone to move through the urinary tract.
• Pain Management: Over-the-counter pain relievers like ibuprofen or acetaminophen can help manage discomfort.
• Dietary Adjustments: Avoiding foods high in oxalates (e.g., spinach, nuts, chocolate) and reducing salt intake may prevent the stone from growing larger.

Tips for Managing Pain and Discomfort

Passing a kidney stone is painful, but these tips help to overcome the discomfort over time.

• Stay Hydrated: Drink water consistently throughout the day. Adequate hydration can help ease the passage of the stone.
• Use Heat Therapy: Applying a heating pad to the affected area can help relieve pain.
• Take Painkiller: Nonsteroidal anti-inflammatory drugs (NSAIDs) can reduce inflammation and alleviate pain. Consult with a healthcare provider before taking any medication.
• Relaxation Techniques: Deep breathing exercises and meditation can help manage pain and reduce stress during the process.

How long does it take to pass a kidney stone?

The amount of time it takes to pass a kidney stone depends on its size. Smaller stones can easily pass through urine without showing symptoms, but larger stones cause complications. The small stones usually pass through the urine within 1-2 weeks without any treatment.

As long as the stone stays in the kidney and isn’t blocking urine flow, it is not noticeable. But when the stone leaves the kidney and moves into the ureter toward the bladder, it causes urine blockage. Stones usually don't block the urethra because it's twice as wide as the ureters. However, if the stone is large, it can cause pain to come back. So, the larger stones take 2-3 weeks to move through the kidneys to the bladder.

This is because ureters are tiny, and if a larger stone is stuck in one, the urine can not flow. This results in swelling and painful spasms (known as renal colic) that cause stabbing pain in the back and side of the back. Sometimes, the pain also radiates to the groyne and genitals. Stones that don’t pass on their own within 4 weeks require medical treatment.

When to see a doctor?

Once the kidney stones have been passed, the symptoms should be improved. Patients need to follow up with a doctor as recommended. However, contact the doctor immediately to prevent further complications if the patient experiences any new issues, especially if you have the following:

• chills, fever
• Unable to urinate
• confusion
• severe fatigue
• nausea, vomiting
• Foul smell or blood clots in the urine

How long is recovery after removing a kidney stone 

The patient's recovery period depends on the physical examination and symptoms after passing a kidney stone. The recovery time after various surgery of patients is as follows

• In Extracorporeal Shock Wave Lithotripsy (ESWL) and Ureteroscopy (URS), the recovery time for the patient is usually 2-3 days, but it requires 1-2 weeks for complete recovery
• In Percutaneous Nephrolithotomy (PCNL), the recovery time might vary; it takes several weeks for full recovery, but individual experiences may vary.
• Open surgery has the longest recovery period of about 4-6 weeks and 8-12 weeks for complete recovery.

Tips for a Smooth Recovery After Kidney Stone Removal

Diet

• Stay Hydrated: Drink plenty of water to help flush out any remaining stone fragments and reduce the risk of new stones forming. Aim for at least 8-10 glasses a day.
• Limit Oxalate-Rich Foods: Reduce intake of foods high in oxalates, such as spinach, nuts, beets, and chocolate, as they can contribute to stone formation.
• Reduce Sodium: Lower your salt intake to prevent the accumulation of calcium in the urine, which can lead to stone formation.
• Balanced Diet: Focus on a balanced diet with plenty of fruits and vegetables. Include foods high in calcium to reduce oxalate absorption but avoid excessive animal protein.

Activity Level

• Rest Initially: Take it easy for the first few days following your procedure. Resting allows your body to heal.
• Gradual Return to Activity: Begin with light activities such as short walks. Avoid heavy lifting, vigorous exercise, or activities that strain your abdomen for at least 1-2 weeks.
• Listen to Your Body: If you feel pain or discomfort, slow down or take a break. It’s important not to push yourself too hard too soon.

Follow-Up Care

• Attend Follow-Up Appointments: Keep all scheduled visits with your healthcare provider to monitor your recovery and check for any complications.
• Take Prescribed Medications: Follow your doctor’s instructions regarding pain relievers, antibiotics, or other medications. They help manage discomfort and prevent infection.
• Monitor Your Symptoms: Be alert to signs of complications such as fever, severe pain, difficulty urinating, or excessive blood in your urine. Report any concerning symptoms to your doctor immediately.
• Follow Dietary Recommendations: If your doctor gives you specific dietary guidelines based on the type of stones you have, follow them closely to prevent recurrence.

Frequently Asked Questions

How long do kidney stones take to form?

This varies with each individual patient. Even for the smaller stones, it usually requires a back-and-forth over several months; however, for people who are at a higher risk of forming them, the formation of stones can occur within weeks.

What are the signs that a person has a kidney stone?

Screening for kidney stones is a frequent procedure, but general screening is not warranted for everybody. Kidney stones are diagnosed by imaging tests, which include X-rays, ultrasound, computed tomography (CT) scan, or magnetic resonance imaging (MRI). The most effective imaging currently available for diagnosing kidney stones is Computerised Tomography or CT scan.

So, if you see crystals in the urine, it does not mean that you have a kidney stone. Crystals are formed very frequently in urine. If you find traces of crystals in your urine alongside other signs of passing kidney stones, you should get an examination and an imaging done.

How can I manage my kidney stones?

Various treatment options are available for kidney stones. Depending on the location, size, hardness, and composition of your stones, you and your physician will be able to choose the best course of therapy for you.

What measures are required to prevent the formation of kidney stones?

Stones can be prevented by altering the composition of urine through diet or use of drugs. Some general dietary recommendations for stone prevention include:

• Increase fluid intake to make 2.5 liters of urine per day
• Limit intake of salt or high salt-containing foods
• Limit intake of non-dairy animal proteins (meat)
• Increase fruit and vegetable intake
• Eat a normal amount of calcium (1,000 to 1,200 mg) per day
• Limit oxalate intake

What are the effects of having a kidney stone in the future?

The presence of kidney stones enhances the processes that lead to the formulation of chronic renal disease. After one stone, you are more likely to have another stone or other complications related to gallstones. Patients who have formed one stone are about 50% likely to form another stone within 5 to 7 years of follow-up.

What is the prevalence of kidney stones in the general population?

On average, about 1 in 10 Canadian population suffer from Kidney stones over a lifetime and 1 in 7 Americans. Men are two times more prone to develop and suffer from kidney stones than women.