Renal Calculi, Nephrolithiasis

What is Renal Calculi, Nephrolithiasis?

Kidney stones are a common reason for blood in the urine and pain in the belly, side, or groin. About 1 in 11 people in the United States will experience kidney stones at some point in their lives, and it affects men twice as often as women. These stones can form because your body isn’t making enough urine or because there is too much of certain substances, like calcium, oxalate, uric acid, cystine, xanthine, and phosphate, which combine to form stones.

Sometimes, kidney stones happen because there is not enough citrate (a substance that inhibits stone formation) in the urine, or because the urine is too acidic. Kidney stones can cause extreme pain, and often people who have them end up in the emergency room. Having kidney stones once will not cause kidney failure. However, having them repeatedly can damage the cells in the tube-like structures in your kidneys, which could lead to loss of kidney function.

What Causes Renal Calculi, Nephrolithiasis?

Urolithiasis, or the formation of urinary stones, happens when substances from the urine crystallize. It can be caused by various factors such as abnormal features in the urinary system that leads to urine collecting and not flowing properly, not drinking enough fluids leading to less urine produced, high amounts of certain substances in diet like oxalate or sodium, urinary tract infections, a systemic acidity in the body, certain medications or diseases, and rare hereditarily acquired conditions like cystonuria.

The majority of patients with kidney stones (around 75% to 85%) usually form calcium stones, which are mainly composed of calcium oxalate or calcium phosphate. Other types of stones formed are uric acid, struvite (composed of calcium magnesium ammonium phosphate), and cystine stones, although they are less common.

Generally, the leading causes of kidney stone formation are not staying hydrated and making low amounts of urine. Other chemical factors that contribute to this include having too much calcium, oxalate, or urate in the urine or not having enough citrate. The most common types and causes of kidney stones include:

1. Calcium stones occur if patients have conditions like hyperparathyroidism or renal calcium leak, high levels of calcium or oxalate in urine, low levels of magnesium or citrate.

2. Uric acid stones are linked with a diet high in foods rich in purine (found in fish, legumes, meat), acidic urine, and certain types of cancers. They may also be associated with gout.

3. Struvite stones are caused by certain bacteria that break down urea into ammonia such as Pseudomonas, Proteus, and Klebsiella.

4. Cystine stones are caused by a metabolic defect leading to the failure of the kidneys in reabsorbing certain substances like cystine, lysine, ornithine, and arginine.

Medications like Atazanavir, Guaifenesin, Indinavir, and others can also cause kidney stones.

Genetics also play a role in the formation of kidney stones. Some families might have genetic mutations that cause problems in how the kidneys process calcium and other substances.

The risk factors for kidney stones include a family or personal history of the condition. Other risk factors that may increase the likelihood of kidney stone formation include conditions like diabetes, hypertension, gout, obesity, and eating a diet high in protein or salt. Reduced fluid intake leads to less urine produced and increased concentration of substances in the urine, which increases the chance of crystal formation. Certain urinary tract infections can lead to high urine pH which can increase the risk for forming certain types of stones.

Having a healthy diet can help reduce the risk of kidney stone formation. This includes eating more fruits and vegetables, reducing meat intake, and lowering your intake of salt. It is advisable to limit foods that contain high levels of oxalate and to ensure adequate fluid intake to maintain a minimum urine output of 2000 mL daily. Beverages high in sugar increases the chance of forming stones, while drinks like coffee could potentially reduce the risk. Although fruit juices might not be beneficial, intake of lemon juice may provide some benefit due to its high citrate content, which is known to reduce stone formation. Cranberry juice’s benefits are not confirmed.

Risk Factors and Frequency for Renal Calculi, Nephrolithiasis

In the United States, the occurrence of urinary stones has been on the rise. The prevalence rate has grown from 3.8% in 1970 to 10.1% in 2016. Men are more likely to develop stone disease than women at a ratio of 2 to 1, but the rate among women is increasing faster.

If you’ve had a urinary stone before, there’s about a 50% chance it could happen again in 10 years. Regions in the Southeastern and South Central US have higher rates, which may be connected to the hot climate and dehydration in these areas.

Before modern treatments, a type of urinary stones known as staghorn calculi had a high mortality rate of 27%. Nowadays, death from stone disease is rare, but specific stone types, particularly staghorn stones and obstructive pyelonephritis, can still lead to significant kidney damage in about 28% of cases.

The risk of kidney stones goes up as you get older, particularly for men over the age of 80. Rates are also growing quickly among children and teenagers. Among kids, teenage girls have the highest rates of kidney stones. Black and Hispanic populations have the lowest incidence of kidney stones, which is impacted more by social and economic factors, access to healthcare, and diet rather than genetics.

Research has shown that people who form stones for the first time have a 26% chance of experiencing it again within 5 years. Certain risk factors make someone more likely to have recurring kidney stones:

• Diabetes
• Family history of kidney stones
• High blood pressure
• Obesity
• Past personal history of urinary stones
• Previous surgeries for stones
• Uric acid urinary stones
• Being of White race
• Younger age at first diagnosis

Having kidney stones is also associated with various health conditions such as heart disease, high blood pressure, chronic kidney failure, diabetes, metabolic syndrome, and obesity. For instance, kidney stone patients with diabetes usually have lower urinary pH levels and higher urinary oxalate, which make them more prone to a specific type of kidney stone.

People with kidney stones are also more likely to develop high blood pressure, artery disease, strokes, heart attacks, and especially kidney failure than people without stones. Patients with multiple recurrences, primary hyperoxaluria, and renal tubular acidosis, as well as those with uric acid, infection stones, staghorn, and cystine stones, are more likely to sustain lasting kidney damage.

Multiple treatments with a procedure called “extracorporeal shockwave lithotripsy” don’t seem to significantly harm the kidneys. According to scientists, the increasing global temperatures due to climate change are expected to hike the incidence of kidney stones by 30% by 2050, especially in hot regions. The global occurrence of kidney stones has been mounting over the past 30 years, putting financial strain on healthcare systems worldwide.

Signs and Symptoms of Renal Calculi, Nephrolithiasis

Nephrolithiasis, or kidney stones, can present in various ways with different symptoms. For instance, about 85% of patients with kidney stones have traces of blood in their urine. However, they might not experience any symptoms until the stones cause urinary obstruction or infection. Kidney stones are often found by accident during scans for unrelated conditions or while investigating the presence of blood in the urine.

People with kidney stones generally experience intense and severe pain in their flank, or side. The pain can often spread to the abdomen and even down to groins, testicles, or labia. This sudden, sharp, and severe pain is also known as renal colic and can be associated with feelings of nausea and vomiting.

In a typical scenario, the severe pain from renal colic peaks within 90 to 120 minutes. The pain can be intermittent, with unbearable pain coming in waves. This initial phase may wake the patient from sleep. The second phase lasting about 3 to 4 hours is characterized by a more constant pain. The third phase is usually less severe with mild relief, but intermittent waves of pain may still persist. This phase can last from 4 to 16 hours.

During a physical examination, the doctor may find tenderness in the area over your kidneys and notice that bowel sounds are weaker than normal. The genital and pubic region may also be tender to touch. Fever is uncommon with renal colic unless there is an infection present. When fever, an elevated white blood cell count, and pus in the urine are found, it could indicate a serious infection in the kidneys or pus-filled renal pelvis.

When kidney stones become infected, the condition can become serious and may potentially be life-threatening; it requires emergency decompression surgery to drain the pus from the renal pelvis. Without prompt treatment, the infection can rapidly worsen causing urosepsis where the infection spreads throughout the body, leading to shock, and potentially death. In severe cases, a percutaneous drainage procedure is preferred, which minimizes the handling of the infected kidney and obstructing stones.

Several factors can increase the risk of developing kidney stones. These include:

• Bone disorders
• Chronic diarrhea, malabsorption
• Diabetes and obesity (especially in women)
• Excessive intake of Vitamin C (>1,000 mg/day)
• Family history of kidney stones
• GI disease
• Gastro bypass surgery (especially Roux-en-Y)
• Gout
• Hyperparathyroidism
• Metabolic syndrome
• Obesity
• Having had urinary stones in the past
• Renal failure
• Renal tubular acidosis
• Sarcoidosis (which can increase calcium and vitamin D levels)

Testing for Renal Calculi, Nephrolithiasis

If your doctor suspects you might have a kidney stone, you’ll be asked to take a urine test. This can reveal blood in your urine, which often but not always happens with kidney stones. Sometimes, this test can also show specific kinds of urine crystals or signs of a urinary infection, which can be treated.

An imaging scan, called a KUB, which targets the kidneys, ureters, and bladder, might be used to see if you have a kidney stone. This scan might not show small stones or stones that aren’t very dense, though. Alternatively, an ultrasound may be used to check for any blockages and swelling, particularly for pregnant women, for whom x-rays are avoided.

Another ultrasound-based test can be used to identify blockages in the kidneys. This test calculates the resistive index, which is a way of measuring blood flow. If the resistive index is above normal, it might be a sign of blockage.

A computerized imaging scan, known as a CT scan, of the abdomen and pelvis without contrast (a dye used to make the images clearer) is the best test for diagnosing kidney stones. This scan can show stones and signs of blockage accurately. If needed, a non-contrast scan should be done before any other scans that require contrast, which can obscure the stones and make them harder to identify.

It’s highly recommended to do a KUB scan before a CT scan as it can provide critical information about the stone that the CT scan might miss. Moreover, if contrast is used, you won’t be able to get a clear x-ray.

A follow-up KUB scan can help your doctor see if the stone is still there without having to resort to another CT scan or a surgical procedure. Combining a KUB scan with renal ultrasound is another acceptable option to avoid a CT scan. This option is less costly and lowers the chance of exposure to radiation.

Certainly, If you have kidney stones, Recommended European Guidelines advise to check urine for blood, measure its pH, and check for bacteria. A urine culture should be gotten, and certain blood tests should be ordered. The doctor will also advise on a non-contrast CT scan.

Treatment Options for Renal Calculi, Nephrolithiasis

Kidney stones can cause severe pain, especially if they block the passage of urine or get infected. To help with the pain, doctors usually provide strong painkillers. Because kidney stones can make people feel nauseous or vomit, they might also be given hydration and anti-sickness drugs through an injection.

Many kidney stones can be managed by observation without the need for surgery. Especially the smaller ones (less than 5 mm in size) have a high chance of passing naturally. There are medications available which can help to facilitate this process. If there’s even a slight suspicion of a urinary tract infection, it’s essential to start antibiotics right away, particularly in people who have diabetes.

Preliminary studies suggest a medication called desmopressin can ease the pain associated with kidney stones. There are other drugs also, such as calcium channel blockers and alpha-blockers, which can relieve pain by helping the ureter, the tube that takes urine from the kidneys to the bladder, relax. Mirabegron is another medication that has shown effectiveness in helping kidney stones pass. Any passed stones should be sent to the lab for testing to understand their chemical makeup.

In some cases, immediate medical intervention is necessary. For example:

– If you have a urinary tract infection along with a blockage from the stone.
– If you have severe pain or nausea that can’t be controlled at home.
– If you only have one kidney, and it’s affected by the stone.
– If both ureters are obstructed at the same time – this could lead to kidney failure.
– Or, if the kidney’s function is deteriorating due to obstruction.

If there’s a urinary tract infection together with an obstructed stone, doctors first need to create a passage for urine to bypass the blockage. This can be achieved with either a double J stent (a small, flexible tube) or a nephrostomy tube (which drains urine from the kidneys through your back). Once the infection is under control, a kidney stone can be removed. In certain situations, such as in patients with severe illness, a nephrostomy tube might be the better initial option.

For larger stones, there are several surgical options available:

– Extracorporeal shockwave lithotripsy is a procedure that uses sound waves to break down stones in the kidneys or upper part of the ureters.
– Ureteroscopy with laser lithotripsy involves using a thin, flexible tube (ureteroscope) fitted with a camera to diagnose and treat stones in the urinary tract, especially those in the lower part of the ureters.
– For large stones, percutaneous nephrolithotomy can be performed. This procedure involves making a small incision in your back and passing a hollow tube (sheath) through your skin into your kidney to remove the stone.

After the treatment, it’s recommended to test the patient’s urine over a 24-hour period to understand the cause of the stone and prevent future ones. This is especially important for those who have multiple prior stones, a single kidney, kidney failure, or are at a high surgical risk.

Patients should understand that preventing kidney stones often means a long-term commitment to certain therapies. Even with these treatments, there may still be a possibility of stone formation, although it will be considerably reduced.

For treating an episode of kidney stones, hospital admission may be necessary in certain cases – such as when pain cannot be controlled with oral painkillers or if there’s a kidney infection associated with the stone.

Dissolving certain types of kidney stones can be done with medication. For instance, uric acid stones can be dissolved by alkalizing (making less acidic) the urine with medications like potassium citrate or sodium bicarbonate. People with high levels of oxalate, a chemical that can contribute to stone formation, can benefit from a low-oxalate diet and calcium supplements.

Patients with a specific type of stone called struvite stones need to control any underlying infections and ensure that all stone fragments are completely removed. An occasional medication resort for these type of stones is acetohydroxamic acid. However, this should be used cautiously as it can have significant side effects.

What else can Renal Calculi, Nephrolithiasis be?

When dealing with symptoms that might suggest kidney stones (renal calculi), doctors also consider other conditions that could present similarly. These include:

• Appendicitis – an inflammation of the appendix
• Benign familial hematuria – a harmless genetic condition causing blood in the urine
• Cholecystitis – inflammation of the gallbladder
• Costochondritis – chest pain caused by inflammation of the chest wall
• Diverticulitis – inflammation or infection of small pouches in the digestive tract
• Focal nephronia – a localized bacterial infection in the kidney
• Glomerulonephritis – inflammation of the kidney’s filtration system
• Hernia – a condition in which part of an organ is displaced and protrudes through the wall of the cavity containing it
• Lobar pneumonia – a form of pneumonia that affects a large and continuous area of the lobe of a lung
• Pelvic inflammatory disease – an infection of the female reproductive organs
• Pyelonephritis – a type of urinary tract infection where the infection has spread from the bladder to the kidneys

What to expect with Renal Calculi, Nephrolithiasis

Around 80% to 90% of kidney stones pass naturally through the body. However, about 3% of patients may need to be hospitalized due to severe pain, inability to pass the stone, or serious problems like infection or dehydration. In some cases, these stones could cause obstruction in the urinary tract and lead to dangerous infections, necessitating an emergency surgery to remove the obstruction or drain the kidney until the infection is treated.

Kidney stones are known to return in about half of the patients within 10 years. Some people may even experience them more frequently. Proactive measures like 24-hour urine testing, coupled with preventive therapy, can drastically lower the recurrence rate. However, patients need to understand the results and be motivated for long-term treatment even if immediate relief isn’t noticeable.

Certain people with ongoing metabolic problems or cancers may be more susceptible to recurrent kidney stones. For all patients suffering from kidney stones, staying well-hydrated is crucial, as no medicine is likely to work without enough hydration and a daily urine output of at least 2000 mL (ideally 2500 mL or more).

Possible Complications When Diagnosed with Renal Calculi, Nephrolithiasis

Nephrolithiasis, or kidney stones, can lead to various complications, which are:

• Formation of abscesses (pockets of pus)
• Bursting of the renal fornix, part of the kidney
• Hydronephrosis, a condition characterized by excess fluid in a kidney due to a backup of urine
• Abscess around the kidney
• Pyelonephritis, which is a type of kidney infection
• Pyonephrosis, another kind of kidney infection generally caused by an obstruction
• Renal colic, characterized by severe pain caused by kidney stones
• Severe conditions like kidney failure, kidney shrinking, and end-stage kidney disease
• Sepsis and urosepsis, serious infections that can spread throughout your body
• Stones in the ureter leading to colic, blockage, pain, and scarring
• Urinary leakage
• Urinoma, an encapsulated collection of urine

Preventing Renal Calculi, Nephrolithiasis

Patients are generally encouraged to avoid diets high in calcium and to limit their intake of excessive salt and animal protein. If you have a medical condition called hyperoxaluria or you often get calcium oxalate stones, a diet low in a substance called oxalate is recommended. It’s important not to cut out too many dairy products or foods high in calcium though, because this can actually lead to a situation where oxalate in your intestines isn’t properly managed, causing hyperoxaluria, an excessive urinary excretion of oxalate, a substance that can cause kidney stones when produced in large amounts.

For those who have had kidney stones (urolithiasis) and are interested, willing, and motivated to do long-term preventive treatment, there’s a 24-hour urine test available. This test helps the doctor understand your risk of developing stones and guides them in prescribing the optimal preventive treatment for you.