Kidney stones - Symptoms, causes, types, and treatment

How common are kidney stones?

Each year, more than half a million people go to emergency rooms for kidney stone problems. It is estimated that one in ten people will have a kidney stone at some point in their life.

The prevalence of kidney stones in the United States increased from 3.8% in the late 1970s to 8.8% in the late 2000s. The prevalence of kidney stones was 10% during 2013-2014. The risk of kidney stones is about 11% in men and 9% in women. Other diseases like high blood pressure, diabetes, and obesity can increase the risk of kidney stones.

What is a kidney stone?

A kidney stone is a hard object that is made of chemicals in urine. There are four types of kidney stones: calcium oxalate, uric acid, struvite, and cystine. A kidney stone can be treated with shock wave lithotripsy, ureteroscopy, percutaneous nephrolithotomy, or nephrolithotripsy. Common symptoms include severe lower back pain, blood in the urine, nausea, vomiting, fever, and chills, or urine that smells bad or looks cloudy.

Urine has various wastes dissolved in it. When there is too much waste in too little liquid, crystals begin to form. Crystals attract other elements and join together to form a solid that will increase in size unless it is eliminated from the body with urine. These chemicals are usually eliminated in the urine by the body's main chemical - the kidney. In most people, having enough fluid flushes them out or other chemicals in the urine stop stones from forming. The chemicals that form stones are calcium, oxalate, urate, cystine, xanthine, and phosphate.

Once formed, the stone can remain in the kidney or travel through the urinary tract to the ureter. Sometimes small stones pass out of the body in the urine without causing too much pain. But stones that don't move can cause urine to collect in the kidney, ureter, bladder, or urethra. This is what causes the pain.

Causes of kidney stones

Possible causes include drinking too little water, exercising (too much or too little), obesity, weight-loss surgery, or eating foods with too much salt or sugar. Infections and family history can be important in some people. Eating too much fructose is correlated with an increased risk of developing kidney stones. Fructose can be found in table sugar and high fructose corn syrup.

Types of kidney stones

There are four main types of stones:

Calcium Oxalate: The most common type of kidney stone that is created when calcium combines with oxalate in the urine. Inadequate calcium and fluid intake, as well as other conditions, can contribute to its formation.
Uric acid - This is another common type of kidney stone. Foods like organ meats and shellfish have high concentrations of a natural chemical compound known as purines. High purine intake leads to increased production of monosodium urate, which, under the right conditions, can form stones in the kidneys. The formation of this type of stone is usually hereditary.
Struvite: These stones are less common and are caused by infections in the upper urinary tract.
Cystine: These stones are rare and tend to run in families. What are cystine stones?

Kidney stone symptoms

Some kidney stones are as small as a grain of sand. Others are as big as a pebble. Some areas big as a golf ball! As a general rule of thumb, the larger the stone, the more noticeable the symptoms.

Symptoms can be one or more of the following:

severe pain on both sides of the lower back
more vague pain or stomach pain that doesn't go away
blood in the urine
nausea or vomiting
fever and chills
urine that smells bad or looks cloudy

Kidney stone begins to hurt when it causes irritation or blockage. This rapidly escalates to extreme pain. In most cases, kidney stones pass harmlessly, but usually not without causing a lot of pain. Pain relievers may be the only treatment needed for small stones. Other treatment may be needed, especially for stones that cause long-lasting symptoms or other complications. In severe cases, however, surgery may be necessary.

Kidney stone treatment

The treatment of kidney stones is similar in children and adults. You may be asked to drink a lot of water. Doctors try to pass the stone without surgery. You may also receive medicine to help your urine be less acidic. But if it is too large, or if it blocks the flow of urine, or if there is a sign of infection, it is removed with surgery.

Shock wave lithotripsy is a non-invasive procedure that uses high-energy sound waves to blow the stones into fragments that are then more easily eliminated in the urine. In ureteroscopy, an endoscope is inserted through the ureter to retrieve or obliterate the stone. On rare occasions, for very large or complicated stones, doctors will use percutaneous nephrolithotomy/nephrolithotripsy.

I think I have a stone. What should I do?

Consult a doctor as soon as possible. You may be asked to drink more fluids to try to pass the stone in your urine. If you filter your urine and can salvage a piece of the stone that has passed, take it to your doctor. Or the stone may need to be removed with surgery.

Kidney stone diagnosis

Diagnosis of a kidney stone begins with a medical history, physical exam, and imaging tests. Your doctors will want to know the exact size and shape of your kidney stones. This can be done with a high-resolution CT scan from the kidneys to the bladder or an X-ray called a "KUB X-ray" (kidney-ureter-bladder X-ray) that will show the size of the stone and its position. Surgeons obtain the KUB radiograph often to determine if the stone is suitable for shock wave therapy. The KUB test can be used to monitor the stone before and after treatment, but a CT scan is generally preferred for diagnosis. In some people, doctors will also order an intravenous pyelogram or IVP, a special type of x-ray of the urinary system that is performed taken after injecting a dye.

Second, your doctors will decide how to treat your stone. The health of your kidneys will be evaluated through blood tests and urinalysis. Your general health and the size and location of your stone will be considered.

Later, your doctor will want to find the cause of the stone. The stone will be tested after it leaves your body, and your doctor will test your blood for calcium, phosphorus, and uric acid. Your doctor may also ask you to collect your urine for 24 hours to test for calcium and uric acid.

Why do doctors examine the contents of the stone?

There are four types of stones. Studying the stone can help you understand why you have it and how to reduce the risk of more stones forming. The most common type of stone contains calcium. Calcium is a normal part of a healthy diet. The kidney generally removes extra calcium that the body does not need. People with stones often keep too much calcium. This calcium combines with waste products like oxalate to form a stone. The most common combination is called calcium oxalate.

Less common types of stones are infection-related stones, which contain magnesium and ammonia called struvite stones, and stones formed from monosodium urate crystals, called uric acid stones, which could be related to obesity and dietary factors. The rarest type of stone is a cystine stone that tends to run in families.

Long-term consequences of kidney stones

Kidney stones increase the risk of developing chronic kidney disease. If you have had a stone, you are at higher risk of having another stone. Those who have developed one stone have a roughly 50% risk of developing another within 5 to 7 years.

Reduce the risk of kidney stones

Drinking enough fluids will help keep your urine less concentrated on waste products. Darker urine is more concentrated, so your urine should appear very light yellow to clear if you are well hydrated. Most of the liquid you drink should be water. Most people should drink more than 12 glasses of water a day. Talk to a healthcare professional about the correct amount of water that is best for you. Water is better than soda, sports drinks, or coffee/tea. If you exercise or if it's hot outside, you should drink more. Sugar and high fructose corn syrup should be limited to small amounts.

Eat more fruits and vegetables, which make your urine less acidic. When urine is less acidic, stones may be less able to form. Animal protein produces urine that has more acid, which can increase the risk of kidney stones.

You can reduce excess salt in your diet. What foods are high in salt? Everyone thinks of salty chips and potato chips. Those should be eaten rarely. Other products are salty: sandwich meats, canned soups, packaged meals, and even sports drinks.

You want to try to reach a normal weight if you are overweight. But high-protein weight-loss diets that include high amounts of animal protein, as well as heavy diets, can increase the risk of stone formation. You need adequate protein, but it must be part of a balanced diet. Seek the guidance of a registered dietitian when embarking on a weight loss diet or any dietary intervention to reduce the risk of kidney stones.

Don't get confused about having a "calcium" stone. Dairy products contain calcium, but they actually help prevent stones, because calcium binds to oxalate before it reaches the kidneys. People with the lowest dietary calcium intake have a higher risk of kidney stones. A stone can be formed from salt, protein waste products, and potassium. The most common type of kidney stone is a calcium oxalate stone. Most kidney stones form when oxalate, a byproduct of certain foods, binds with calcium as the kidneys make urine. Both oxalate and calcium increase when the body does not have enough fluids and also has too much salt. Based on blood and urine tests, your doctor will determine what kinds of dietary changes are necessary for you.

Some herbal substances are promoted to help prevent stones. You should know that there is not enough published medical evidence to support the use of any herb or supplement to prevent stones.

Consult your doctor and/or a registered dietitian about how to make dietary changes if you have had a stone or think you may be at increased risk for a kidney stone. To guide you, they need to know your medical history and the foods you eat. Here are some questions you can ask:

What Food Can Cause Kidney Stone?
Should I Take Vitamin and Mineral Supplements?
What drinks are good options for me?

Can Children Get Kidney Stones?

Kidney stones are found in children as young as 5 years old. In fact, this problem is so common in children that some hospitals run "stone" clinics for pediatric patients. The increase in the United States has been attributed to several factors, primarily related to food choices. The two biggest reasons are not drinking enough fluids and eating foods that are high in salt. Children should eat fries and fries less salty. There are other salty foods: sandwich meats, canned soups, packaged meals, and even some sports drinks. Soda and other sweetened beverages can also increase the risk of stones if they contain high fructose corn syrup.