Kidney Stones: Understanding Causes, Symptoms, and PreventionJan 09, 2024
Kidney Stones: Understanding Causes, Symptoms, and Prevention
Kidney stones are a common health condition that affects millions of people worldwide. These hard, pebble-like deposits can form in one or both kidneys and cause great discomfort, pain, and even serious complications. While the causes of kidney stones can vary, they all share a common factor: a buildup of mineral and salt deposits in the kidneys that become too large to pass through the urinary tract.
It is an increasing kidney disorder in humans, affecting 12% of the world's population. It affects all ages, sexes, and races but occurs more frequently in men than in women between the ages of 20–49. If patients do not apply metaphylaxis, the relapsing rate of secondary stone formations is estimated to be 10–23% per year, 50% in 5–10 years, and 75% in 20 years of the patient.
What Are Kidney Stones?
Kidney stones are small, hard deposits that form in the kidneys when there is an excess of certain minerals and salts in the urine. When these substances are in high concentrations, they can crystallize and clump together, forming stones of varying sizes.
Kidney stones can range in size from a grain of sand to a golf ball and can cause significant discomfort as they move through the urinary tract. The most common types of kidney stones are calcium stones, which are made up of calcium oxalate or calcium phosphate.
Other kidney stones include uric acid, struvite, and cystine stones. Uric acid stones form when there is too much uric acid in the urine, while struvite stones develop due to a urinary tract infection. Cystine stones are rare and are caused by a genetic disorder that affects how the kidneys process certain amino acids.
Urinary System and Stone Formation
The urinary system filters waste products and excess fluids from the bloodstream. The kidneys are the primary organs responsible for blood filtration in the urinary system. The filtration process starts with the glomerulus, a small blood vessel in the kidneys. The glomerulus acts as a filter that allows small particles, such as water, glucose, and minerals, to pass through while preventing larger molecules, such as proteins and blood cells, from leaving the bloodstream.
Once the blood has been filtered through the glomerulus, the resulting fluid, called filtrate, enters the renal tubule, a long, winding tube that transports the filtrate through the kidneys. Different substances are reabsorbed into the bloodstream or excreted in the urine as the filtrate flows through the renal tubule, depending on the body's needs. For example, the kidneys may reabsorb glucose or amino acids if the body needs them or excrete excess potassium or sodium if levels are too high.
Kidney stones can form when certain substances become concentrated in the urine and form crystals. The mechanism of stone formation varies depending on the type of stone. Calcium oxalate stones are the most common type, forming when the oxalate concentration in the urine is high and acidic.
Uric acid stones form when the urine is too acidic and the concentration of uric acid is high. Struvite stones form due to bacterial infections in the urinary tract, and cystine stones occur when the body excretes too much of the amino acid cysteine. Kidney stone formation can be attributed to several factors, including dehydration, a diet high in animal protein, too much salt, and certain medical conditions like inflammatory bowel disease. Understanding the mechanism of stone formation can help individuals take steps to prevent the development of kidney stones.
Symptoms of Kidney Stones
The symptoms of kidney stones can vary depending on the size and location of the stone. Small stones may not cause noticeable symptoms, while larger stones can cause severe pain and discomfort. Some of the most common symptoms of kidney stones include:
- Sharp pain in the back or side, often radiating to the groin
- Painful urination
- Blood in the urine
- Nausea and vomiting
- Frequent urination
- Difficulty urinating
- Foul-smelling urine
If you experience these symptoms, seeing a healthcare provider for an accurate diagnosis and treatment plan is important.
Risk Factors for Kidney Stones
While anyone can develop kidney stones, certain factors can increase your risk. Some of the most common risk factors for kidney stone formation include:
Dehydration: Not drinking enough fluids can lead to a buildup of minerals and salts in the urine, increasing the risk of stone formation.
Family history: If someone in your family has had kidney stones, you may be more likely to develop them.
Certain medical conditions: Digestive and kidney diseases, chronic kidney disease, and inflammatory bowel disease can all increase the risk of kidney stone formation.
Certain medications: Some medications, such as diuretics and antacids, can increase the risk of kidney stones.
Diet: Consuming too much animal protein, salt, and oxalate-rich foods like spinach, beets, and nuts can increase the risk of kidney stones.
Mechanism of Kidney Stone Formation
Kidney stones form when there is an excess of mineral and salt deposits in the urine. These deposits can accumulate and form crystals, clumping together to form stones.
The exact mechanism of kidney stone formation is not fully understood, but certain factors are known to contribute to their development. One of the primary factors is urine pH. When the urine is too acidic or alkaline, it can increase the risk of crystal formation.
Another factor that can contribute to kidney stone formation is urine flow. When urine flow is blocked or slowed down, it can cause minerals and salts to accumulate in the urine, increasing the risk of stone formation.
Diagnosis of Kidney Stones
If a person experiences symptoms of kidney stones, they should seek medical attention from a healthcare provider. The healthcare provider will typically perform a physical exam and order tests to diagnose the presence and type of kidney stones.
Imaging tests, such as X-rays, CT scans, and ultrasounds, can help the healthcare provider see the location and size of the kidney stones. These tests can also identify any complications, such as urinary tract obstruction.
Urine tests can help the healthcare provider determine the composition of kidney stones. The urine can be analyzed for calcium, oxalate, uric acid, and other substances contributing to stone formation.
Blood tests can help the healthcare provider identify any underlying medical conditions that may contribute to kidney stone formation. For example, blood tests can detect high uric acid levels, indicating gout or other metabolic disorders.
Types of Kidney Stones
Kidney stones can vary in composition, and the type of stone can influence the symptoms, treatment options, and preventive measures. The following are the four main types of kidney stones:
Calcium stones are the most common type of kidney stone, accounting for approximately 80% of all cases. They are made up of calcium oxalate or calcium phosphate. Calcium oxalate stones are more common and are formed when high oxalate levels are present in the urine. Oxalate is a naturally occurring substance in many foods, such as spinach, rhubarb, nuts, and tea. Oxalate is produced and excreted in the urine when the body processes these foods. The urine can combine with calcium to form stones with high oxalate levels.
Calcium phosphate stones are less common and are formed when there is an imbalance of acid and alkaline in the urine. This type of stone is more likely to form in people with metabolic conditions, such as renal tubular acidosis, where the body produces too much acid and not enough alkaline.
Uric Acid Stones
Uric acid stones are the second most common type of kidney stone, accounting for approximately 10% of all cases. They are formed when too much uric acid is in the urine, which can be caused by a high protein diet or a medical condition, such as gout or leukemia. Uric acid stones are more common in men than women.
Struvite stones, also known as infection stones, are formed due to a urinary tract infection. They are made of magnesium, ammonium, and phosphate and can grow very quickly, often filling the entire kidney. Struvite stones can cause serious complications, such as kidney damage and sepsis, and require prompt treatment.
Cystine stones are the rarest type of kidney stone, accounting for less than 1% of all cases. They are caused by a genetic disorder that affects how the body processes cystine, an amino acid. Cystine stones are more common in children and can recur even after treatment.
Treatments of Kidney Stones
If a patient has symptoms of kidney stones, the doctor will perform some diagnostic tests to confirm the presence of kidney stones. Once confirmed, the treatment options depend on the stones' size, location, and composition. Some of the commonly used treatments for kidney stones are:
- Observation and pain management:
A healthcare provider may advise observation and pain management for small stones less than 5mm. The patient may be prescribed medication to manage pain and encouraged to drink plenty of water to help the stone pass through urine.
- Extracorporeal Shock Wave Lithotripsy (ESWL):
This non-invasive procedure uses sound waves to break kidney stones into smaller pieces, which can pass through urine easily. This procedure is effective for stones smaller than 2cm in size and in the kidney or upper urinary tract.
This procedure is used for stones in the lower urinary tract or ureter. A thin tube with a camera attached to the end, a ureteroscope, is inserted into the ureter to locate the stone. The stone is then broken into smaller pieces using laser energy and removed through the tube.
- Percutaneous Nephrolithotomy (PCNL):
This invasive procedure is used for large stones more than 2cm in size and located in the kidney. A small incision is made in the back, and a scope is inserted to locate the stone. The stone is then broken into smaller pieces using ultrasound or laser energy and removed through the scope.
- Open Surgery:
This is the last resort used for very large or complex stones that cannot be treated with any other procedure. The surgeon makes an incision in the back or side and removes the stone through the opening.
In addition to the above treatments, the healthcare provider may prescribe medication to help break down the stone, control infection or manage pain. Some of the commonly prescribed medications for kidney stones are:
- Alpha-blockers: These medications relax the muscles in the ureter, making it easier for the stone to pass through urine.
- Pain relievers: Nonsteroidal anti-inflammatory drugs (NSAIDs) or opioids may be prescribed to manage pain associated with kidney stones.
- Antibiotics: If the stone is causing an infection or if the patient has a history of recurrent urinary tract infections, antibiotics may be prescribed.
- Medications to prevent stone formation: If the patient has a history of recurrent kidney stones, the healthcare provider may prescribe medications to prevent stone formation. The type of medication depends on the type of stone the patient has. For example, thiazide diuretics may be prescribed to prevent calcium stones, and allopurinol may be prescribed to prevent uric acid stones.
Following the healthcare provider's advice regarding treatment and medication is important. Failure to treat kidney stones promptly and effectively can lead to complications such as kidney damage, recurrent infections, and chronic kidney disease.
Preventive measures for kidney stones:
Preventing kidney stones is crucial, particularly for people with a history of developing kidney stones. The following are some preventive measures that can help reduce the risk of developing kidney stones:
- Drink plenty of fluids:
Drinking enough fluids, particularly water is essential to prevent the formation of kidney stones. Drinking enough fluids ensures that the urine is diluted and that stone-forming substances are not concentrated in the urine. Experts recommend drinking at least 2-3 liters of fluids per day.
- Limit salt intake:
High salt intake can increase the risk of developing kidney stones. People prone to kidney stones should limit their salt intake to less than 2,300 milligrams daily.
- Limit animal protein:
Animal protein, such as meat, poultry, and fish, can increase the risk of developing kidney stones. People prone to kidney stones should limit their animal protein intake to no more than 6 ounces per day.
- Limit foods high in oxalate:
Some foods are high in oxalate, which can contribute to the formation of kidney stones. Foods high in oxalate include spinach, rhubarb, beets, nuts, chocolate, and tea. People prone to kidney stones should limit their intake of these foods.
- Take medications as prescribed:
People prone to developing kidney stones may need medication to prevent their formation. It is essential to take these medications as prescribed by a healthcare provider.
- Monitor calcium intake:
Some people may develop kidney stones due to too much calcium intake. However, limiting calcium intake may not always be the best solution, as calcium is essential for maintaining bone health. Monitoring calcium intake and talking to a healthcare provider about the appropriate amount is best.
- Maintain a healthy weight:
Obesity can increase the risk of developing kidney stones. Maintaining a healthy weight through a healthy diet and regular exercise can help prevent the formation of kidney stones.
- Talk to a healthcare provider about supplements:
Some supplements, such as vitamin C and calcium supplements, can increase the risk of developing kidney stones. Talking to a healthcare provider about the appropriate supplements to prevent kidney stones is essential.
Kidney stones can be painful and challenging to manage. However, with proper diagnosis, treatment, and preventive measures, they can be effectively managed, and complications can be avoided. If you suspect that you may have kidney stones, you must talk to a healthcare provider immediately to get the appropriate diagnosis and treatment.