What is Urolithiasis?

Renal stones, or kidney stones, are created inside your kidneys and this condition is called nephrolithiasis. Urolithiasis happens when these stones leave the kidney area and travel down into the rest of your urinary system, which includes the tubes that carry urine from the kidneys to the bladder called the ureters, the bladder itself, and the tube that carries urine out of the body, the urethra. Many patients with urolithiasis can be treated by just closely monitoring their condition, along with taking painkillers and medication to stop feelings of sickness. However, if the stones are causing a blockage, kidney failure, or an infection, more serious treatments will be needed.

What Causes Urolithiasis?

Kidney stones are grouped into several types. However, the majority of them, about 80%, are composed of a substance called calcium oxalate or phosphate. Less common types of kidney stones include uric acid (9%), struvite (10%), and cystine (1%). Your risk of getting different types of stones can depend on factors such as your diet, family history of kidney stones, environmental conditions, medications, and your overall health.

The intake of certain foods and insufficient daily liquid intake could increase your risk of developing kidney stones. This includes drinking less water, eating a lot of animal proteins, foods high in oxalate like beans, beer, berries, coffee, chocolate, some nuts, some teas, soda, spinach, potatoes, and foods high in salt. Doctors recommend drinking enough fluids to produce about 2.5 liters of urine per day to prevent kidney stones. Water, coffee, tea, beer, and low-sugar fruit juices are good choices, except for tomato (high in salt), grapefruit, and cranberry (high in oxalate). Consuming foods rich in citrate can lower the chances of stone formation, as it prevents solid crystals from forming by binding with calcium present in urine.

Surprisingly enough, a low intake of calcium could potentially increase your risk for kidney stones. While contrary to what most people think, calcium decrease will affect the amount available in your GI tract, which is used to bind to oxalate. Increased oxalate levels, in turn, lead to a higher risk of stone formation. Too much Vitamin C and fish oil can also raise your chances of getting kidney stones.

If you or your family have a history of kidney stones, you are more likely to get them again. Certain procedures like gastric bypass or sleeve gastrectomy also elevate the chance of calcium oxalate stone formation, due to increased levels of oxalate in urine and decreased urine production after surgery. Having chronic conditions like kidney disease, high blood pressure, gout, type 2 diabetes, obesity, and certain types of cancer could increase your risk. Obesity and type 2 diabetes are especially linked to the formation of calcium oxalate and uric acid stones.

Certain medications can also cause kidney stones, although this is rare. Drugs used to treat HIV and a drug called sulfadiazine are primary culprits.

Struvite stones, also known as infection stones, are less common and can take a while to become noticeable. They are often formed due to a higher urine pH. Uric acid stones tend to form with lower levels of uric acid, urine that is too acidic, and low urine output.

Cystine stones are very rare, due to a genetic disorder that affects how the body metabolises and transports cystine, which results in a condition called cystinuria and formation of stones. These often show up in childhood or adolescence, but in some cases have also been observed in infants.

Risk Factors and Frequency for Urolithiasis

Urolithiasis, often referred to as urinary or kidney stones, is a common condition that affects 1 in 11 people in the U.S. It is a significant burden on the healthcare system, costing around $5 billion and causing about 1 million visits to the emergency department each year. This condition is on the rise, notably impacting the working-age population. Men are slightly more affected than women, with rates of 10.6% vs. 7.1%. Obesity is a significant risk factor, acting as a leveler, with overweight people of both genders being more susceptible to kidney stones. The prevalence of this condition varies across ethnic groups; white, non-Hispanic men have been observed to have the highest rates, followed by Hispanic and then black non-Hispanic individuals. Women form a specific type of kidney stone called struvite stones more often than men, due to their higher frequency of urinary tract infections.

A worrying aspect of this condition is the high recurrence rate. About half of the people who have had an episode of urolithiasis may experience a recurrence within five years of the initial episode.

Signs and Symptoms of Urolithiasis

Kidney stones can result in a variety of symptoms. These can range from no symptoms at all to severe health issues. Symptoms often start abruptly or gradually and include severe pain in the abdomen or flank region that comes and goes, blood in the urine (seen under a microscope in 90% of cases), nausea, vomiting, and fever.

On physical examination, the abdomen usually appears normal and is not distended. The location of the pain can vary depending on where the stone is in the urinary tract. It can cause pain in the back or side if the stone is close to the junction between the kidney and the ureter—the tube that carries urine from the kidney to the bladder. If the stone is closer to the bladder, it can cause pain in the groin, scrotum, or labia. Children with kidney stones might seem cranky or cry more than usual, have fevers, and vomit. Patients typically seem restless and shift their positions frequently, seeking relief from the pain.

In more severe cases, stones can obstruct the urinary tract or lead to a bad infection (sepsis). Patients with these complications might seem mildly confused to unconscious due to severe metabolic abnormalities. If there’s a severe infection or sepsis, patients might also show signs of instability in their vital signs such as blood pressure and heart rate.

Testing for Urolithiasis

When a doctor suspects that a patient might have urolithiasis, which is a fancy word for urinary stones, they’ll typically order several lab tests. These include urine analysis (which looks at red and white blood cells in the urine), a pregnancy test in women of reproductive age, and some blood tests. These tests can provide clues on whether the patient has urinary stones.

For a more definite answer, the doctor may need to do imaging tests. The kind of imaging test they choose depends on things like the patient’s body size, whether the patient is pregnant, the cost, and the potential exposure to radiation the test might cause.

An ultrasound scan of the kidneys is a good first choice, especially for children and pregnant women, because it doesn’t expose the patient to radiation. The ultrasound screen will show where the stones are in the kidneys and if there’s a blockage caused by the stones. Also, the ultrasound will show how fast the urine is flowing. However, the ultrasound may not be as good at seeing the stones in patients with a larger body size, and the accuracy can sometimes depend on the skill of the person doing the ultrasound.

An X-ray of the kidneys, ureters, and bladder can be used to look for certain types of stones that show up on X-rays, but it’s not very good at finding stones that are made of certain materials. X-rays can be helpful to see if the stone is growing over time.

A CT scan of the abdomen and pelvis is the best test to check for stones in the ureter (the tube that carries urine from the kidney to the bladder), but it does expose the patient to radiation. With a CT scan, the doctors can see almost all types of stones. But very small stones or those caused by certain HIV medications might not show up. The CT scan can also help the doctors decide if a specific treatment, like a procedure that uses sound waves to break up the stone, would work well.

Finally, an MRI scan is another option to image urinary stones. It’s better than an ultrasound or X-ray but not as good as a CT scan. MRI scans are also safe for pregnant and pediatric patients as they do not involve radiation. However, they tend to be more expensive, take more time, and may not be available in the emergency room, where many patients with urinary stones end up.To make things as easy as possible, doctors use a tool called the STONE score, which uses a few simple pieces of information to estimate if a patient is likely to have a urinary stone.

Treatment Options for Urolithiasis

The treatment of ‘urolithiasis’ or kidney stones depends on the patient’s current condition and symptoms. It can include medication as well as surgery. One of the first steps when a patient comes in is to control pain. Doctors primarily use anti-inflammatory medications, but stronger painkillers can be used for very severe pain. If you’re feeling nauseated, medications can also help control this.

Some medications, called ‘alpha-blockers’, can help larger stones (5-10 millimeters in size) pass through the urinary system. However, they may not be very effective for smaller ones. Fluids can be given to patients who are dehydrated due to vomiting, however, it doesn’t guarantee that the stones will pass.

Around 86% of kidney stones will pass without medical intervention within 30-40 days, depending on their size. Stones that are smaller, less than 2 millimeters in size, usually pass within 8 days and have an 87% likelihood of passing naturally. The bigger the stone, the longer it will take to pass and the lower the chances are of it doing so on its own.

Patients with small stones and no serious symptoms can be managed with medication and observation. However, patients who have larger stones, signs of kidney failure, severe symptoms like vomiting, inability to eat, in serious distress, in pregnancy, or in children may need immediate medical (usually surgical) attention. Your doctors will determine the best course of action based on your individual health, medical history and the severity of your symptoms.

There are several different types of surgical interventions that are used to treat kidney stones; these usually involve breaking down and removing the stones. These methods include ‘extracorporeal shockwave lithotripsy (ESWL)’ where soundwaves are used to break up the stones, ‘ureteroscopy’ where a small tube is used to view and remove the stones, and ‘percutaneous nephrolithotomy (PCNL)’ where a small incision is used to reach and remove the stone.

If kidney stones cause a blockage and an infection, this is a medical emergency that needs immediate attention. In such cases, a tube might have to be placed to drain urine from the kidney to prevent further damage and control the infection.

For patients with recurring stones, medications can help prevent the formation of new stones. These usually include diuretics, specialized salts and other medications focused on reducing the formation of specific types of stones. Lifestyle modifications, like increasing fluid intake and reducing certain types of foods, may also be recommended.

Outpatient care involves tests to help determine what’s causing the stones and plan the best way to manage the issue in the long run, which typically involves avoiding and treating the formation of new kidney stones.

Doctors often rely on specific clinical prediction rules like the STONE criteria when they suspect a patient might have kidney stones. Higher STONE scores mean a higher likelihood of kidney stones and vice versa. Nonetheless, there are numerous other conditions that could cause similar symptoms.

Lower urinary tract infection
Pyelonephritis (kidney infection)
Renal (kidney) abscess
Renal artery aneurysm (blood vessel abnormality)
Appendicitis
Diverticulitis (gut infection)
Mesenteric ischemia (poor blood flow to intestines)
Pancreatitis (inflamed pancreas)
Cholecystitis (inflamed gallbladder)
Small bowel obstruction
Ovarian torsion (twisted ovary)
Dysmenorrhea (painful periods)
Ectopic pregnancy
Spontaneous abortion
Pelvic inflammatory disease (PID)
Constipation

It’s pivotal for the physician to take these potential conditions into consideration and perform necessary tests to ensure accurate diagnosis.

What to expect with Urolithiasis

Most people with kidney stones (urolithiasis) are in great shape and can expect a positive outcome.

Asymptomatic/calyceal stones (non-struvite) are stones that don’t cause symptoms and are typically found in the small, cup-shaped parts of the kidneys. they usually don’t need immediate treatment. Instead, they can be routinely checked with non-invasive tests like ultrasound or KUB, a type of X-ray that looks at your kidneys and bladder.

Stones that are smaller than 5-6 mm are likely to pass through your body on their own, and can be treated with symptom management. This can include medication to control nausea (anti-emetics), pain relief (analgesia), drinking more fluids, and medication to help the stone pass more easily (alpha-receptor antagonists like tamsulosin). Those with small stones should work on changing certain lifestyle or health factors to avoid getting more stones in the future.

Larger stones might need more advanced treatments like shock wave lithotripsy, where sound waves are used to break up the stones, percutaneous nephrolithotomy, a surgical procedure to remove large stones from the kidney, or a combination of the two. However, the outlook for these patients is good, especially if they manage their risk factors well.

For stones that have caused an infection, prompt treatment typically leads to a good outcome. This can involve the use of antibiotics, stabilizing the patient’s vital signs (hemodynamic stabilization), and procedures to remove the stone causing the infection.

Possible Complications When Diagnosed with Urolithiasis

Complications related to kidney problems and infections can occur due to obstruction. These include:

Acute renal failure: this is due to the blockage in your kidneys.
Anuria: it’s a condition where your body isn’t producing urine as it should be.
Urinary tract infection with renal obstruction: an urinary tract infection can occur when your kidneys are blocked.
Sepsis: this happens when an infection reaches your bloodstream.

Preventing Urolithiasis

Patients who have had kidney stones are advised to drink a lot of fluids (about 2.5 to 3.5 litres per day) to keep themselves from getting more stones. They should also try to avoid foods and drinks that are high in substances called oxalates, especially if they’ve had calcium stones before. Oxalates are found in certain types of food and can contribute to stone formation.

If the doctor decides to manage the condition with regular check-ups rather than immediate treatment, patients should come back for another scan or check-up 14 days after they were diagnosed. They may also be given a type of pain medication called non-steroidal anti-inflammatory drugs (NSAIDs) and a special strainer to use when urinating, which will help to see if the stone has passed out of the body.

Maintaining a healthy lifestyle, including losing weight if you’re overweight, is important too. A balanced diet with less salt is also recommended. Studies have shown that avoiding certain supplements, like fish oil and vitamin C, can also reduce the chance of forming more stones. Drinking citric acid in the form of lemon, orange, or melon juice is beneficial as it helps to prevent stone formation too.

Contrary to popular belief, having more calcium in your diet (through foods like milk, tofu, orange juice and almonds) can actually reduce the risk of forming stones. This is because calcium binds with oxalate in the digestive system, reducing the amount of oxalate that can become a stone in the urine.