Updated: August 22, 2018
Kidney stones also called as renal lithiasis or nephrolithiasis are hard deposits made of mainly calcium oxalate and other minerals and salts that form inside your kidneys. Kidney stones usually originate in your kidneys. However, they can develop anywhere along your urinary tract from your kidneys to your bladder. Often, stones form when the urine becomes concentrated, allowing minerals to crystallize and stick together.
Kidney stones can grow to the size of a golf ball while maintaining a sharp, crystalline structure. The stones may be small and pass unnoticed through the urinary tract, but they can also cause extreme pain as they leave the body.
These can be quite painful, but the stones usually cause no permanent damage if they are recognized in a time. You may need to take pain medication and drink lots of water to pass a kidney stone. But if the stones become lodged in the urinary tract, they are associated with a urinary infection or cause complications. Surgery may be needed in such cases. If you are at increased risk of developing them again, your doctor may recommend preventive treatment to reduce your risk of recurrent kidney stones.
The causes of kidney stones vary according to the type of stone.
Symptoms of kidney stones may not occur until the stone begins to move down the ureters. Once the symptoms of kidney stones become apparent they can cause severe pain. This severe pain is called renal colic. The pain generates on one side of your back or abdomen. Pain may radiate to the groin area in case of men. The pain of renal colic comes and goes, but can be intense. People with renal colic tend to be restless.
Other symptoms of kidney stones can include:
There is no definite, single cause for kidney stones, although several factors may increase your risk. Kidney stones are formed when your urine contains more crystal forming substances such as calcium, oxalate and uric acid than the fluid in your urine can dilute. Sometimes your urine may lack substances that prevent crystals from sticking together, which creates an ideal environment for kidney stones to form. Knowing the type of kidney stone helps determine the cause and hence makes it easier to reduce your risk of getting more kidney stones. Try to save your kidney stone if you pass one so that you can provide it for analysis. Kidney stones are made up of different crystals. The different types of kidney stones include:
Most kidney stones are calcium stones, usually in the form of calcium oxalate. Oxalate is a naturally occurring substance made daily by your liver and also found in certain food. Some fruits and vegetables, as well as nuts and chocolate, have high oxalate content. Eating fewer oxalate-rich foods can reduce your risk of developing this type of stone. High-oxalate foods include potato chips, peanuts, chocolate, beets, spinach.
Even though some kidney stones are made of calcium, getting enough calcium in your diet can prevent stones from forming. Dietary factors, high doses of vitamin D, intestinal bypass surgery and several metabolic disorders can increase the concentration of calcium or oxalate in urine.
Calcium stones may also occur in the form of calcium phosphate or maleate. This type of stone is more common in metabolic conditions, such as renal tubular acidosis. These are also associated with certain migraine headaches or with taking certain seizure medications, such as topiramate.
Struvite stones form in response to an infection, such as a urinary tract infection. It occurs mostly in women. These stones can grow quickly and become quite large, and can cause urinary obstruction. Sometimes with few symptoms or little warning it goes undiagnosed untill it create problem. Treating an underlying infection can prevent the development of struvite stones.
Uric acid stones can form in people who don't drink enough fluids or who lose too much fluid. Those who eat a high-protein diet, and those who have gout or or those going through chemotherapy can also develop this type of stone. This type of stone develops when urine is too acidic which can be due to a diet rich in purines. Purine is a colorless substance found in animal proteins, such as fish, shellfish, and meats.
Certain genetic factors also may increase your risk of uric acid stones.
Cystine stones are rare. These stones form in people with a hereditary disorder cystinuria, that causes the kidneys to excrete too much of certain amino acids to urine.
If a person is making less than one liter of urine per day because of any reason, he is at higher risk of developing kidney stones. This is why kidney stones are common in premature infants who have kidney problems. However, people between the ages of 20 and 50 are most likely to develop kidney stones. Men are more likely to develop kidney stones than women. Other risk factors include:
You are more likely to develop stones, if someone in your family has kidney stones. Also if you have already had one or more kidney stones, you are at increased risk of developing another.
Not drinking enough water each day increases your risk of kidney stones. People who live in warm climates and those who sweat a lot may be at higher risk than others.
Eating a diet that is high in protein, sodium (salt) and sugar may increase your risk of some types of kidney stones. This is especially true with a high-sodium diet. Too much salt in your diet increases the amount of calcium that your kidneys must filter. If your kidney is not able to perform this task, that significantly increases your risk of kidney stones.
High body mass index (BMI), large waist size and weight gain have been linked to an increased risk of kidney stones.
Surgery such as gastric bypass surgery, and some disease such as inflammatory bowel disease or chronic diarrhea can cause changes in the digestive process that affect your absorption of calcium and water. This results in increasing the levels of stone forming substances in your urine.
Diseases and conditions that may increase your risk of kidney stones include renal tubular acidosis, cystinuria, hyperparathyroidism, and some urinary tract infections.
Certain medications such as diuretics, antiseizure drugs, and calcium-based antacids can also increase the risk of kidney stone.
Kidney stones don't always stay in the kidney. Sometimes they pass from the kidney into the ureters. The stones may be too large to pass smoothly down the ureter to the bladder. As ureters are small and delicate, passage of stones down the ureter can cause spasms and irritation of the ureters. Sometimes stones block the flow of urine. This is called a urinary obstruction which can lead to kidney infection and kidney damage. People with kidney stones have a significantly higher risk of developing chronic kidney disease.
Several different tests can be done to verify the existence of a kidney stone. A physical examination may reveal the pain in the groin and the lower near the kidneys which are often warning signs of the condition.
Other tests include:
You may be asked to urinate through a strainer to catch stones that you pass. These stone will then send for lab analysis which will reveal the type of your kidney stones. Your doctor uses this information to determine the exact cause of your kidney stones and accordingly plan a treatment to prevent formation of more kidney stones. A 24 hour urine collection test may show that you are excreting too many stone forming minerals or too few stone preventing substances. For this test, your doctor may request that you perform two urine collections over two consecutive days. The following tests can rule out obstruction:
These imaging tests may show kidney stones in your urinary tract. Simple abdominal X-rays, can miss small kidney stones. However, a high speed or dual energy computerized tomography (CT) can reveal even tiny stones. Other imaging options such as an ultrasound, a noninvasive test, and intravenous urography, involves injecting dye into an arm vein and taking X-rays (intravenous pyelogram) or obtaining CT images (CT urogram) as the dye travels through your kidneys and bladder. The contrast dye used in the CT scan and the IVP can affect kidney function. However, this isn't a concern in people with normal kidney function.
As some medications can also increase the potential for kidney damage in conjunction with the dye, make sure to inform your radiologist about any medications you are taking.
Pregnant women should receive an ultrasound rather than a CT scan to avoid unnecessary radiation. Once a person is diagnosed with a kidney stone, simple X-rays will be used to track the progress of the stone through the excretory system.
Treatment for kidney stones varies, depending on the type of stone and the cause. Small stones with minimal symptoms often won't require invasive treatment. You may be able to pass a small stone by drinking as much as fluid. Drinking 1.9 to 2.8 liters a day may help flush out your urinary system. You should drink enough fluid, mostly water to produce clear or nearly clear urine.
People who are dehydrated or have severe nausea and vomiting may need intravenous fluids. Passing a small stone can cause some discomfort. Your doctor may recommend pain relievers such as ibuprofen, acetaminophen or naproxen sodium to relieve mild pain.
Sometimes, your doctor may give you an alpha blocker to help pass your kidney stone. These medication relaxes the muscles in your ureter, helping you pass the kidney stone more quickly and with less pain.
For large stones and those that cause symptoms treatment may include surgery and other methods. As large stones can cause bleeding, kidney damage or ongoing urinary tract infections, they may require more extensive treatment. These include:
Depending on size and location of the stone your doctor may recommend ESWL. ESWL or Extracorporeal shock wave lithotripsy uses sound waves to break up large stones so they can more easily pass down the ureters into your bladder. This procedure lasts about 45 to 60 minutes and can cause moderate pain. Light anesthesia may be given to make you comfortable. It can cause bruising on the abdomen and back and bleeding around the kidney and nearby organs, and discomfort as the stone fragments pass through the urinary tract.
Stones are removed through a small incision in your back using small telescopes and instruments. This procedure and may be needed when:
A thin lighted tube called ureteroscope equipped with a camera will be passed through your urethra and bladder to your ureter when a stone is stuck in the ureter or bladder. Once the stone is located, special tools can snare the stone or break it into pieces that will pass in your urine. Your doctor may then place a small stent in the ureter to relieve swelling and promote healing. You may need general or local anesthesia during this procedure.
Hyperparathyroidism is one of the underlying cause of kidney stone. Your calcium levels can become too high and kidney stones may form when the parathyroid glands produce too much parathyroid hormone. Parathyroid glands, which are located on the four corners of your thyroid gland, just below your Adam's apple.
When a small, benign tumor forms in one of your parathyroid glands you may develop hyperparathyroidism or you develop another condition that leads these glands to produce more parathyroid hormone resulting in formation of calcium phosphate stones. Removing the growth from the gland stops the formation of kidney stones. Treatment of the condition that is causing your parathyroid gland to overproduce the hormone may also help.
Prevention of kidney stones may include a combination of lifestyle changes and medications. Your risk of kidney stones can be reduced by:
Medications can control the amount of minerals and salts in your urine and may be helpful in people who form certain kinds of stones. The type of medication to be used will depend on the kind of kidney stones you have. Thiazide diuretic or a phosphate containing preparation can be prescribed for calcium stones. Allopurinol such as Zyloprim, Aloprim are prescribed to reduce uric acid levels in your blood and urine and a medicine to keep your urine alkaline. In some cases, allopurinol and an alkalizing agent may dissolve the uric acid stones. Long-term use of antibiotics in small doses may help keeping your urine free of bacteria that cause infection to prevent struvite stones. Medication can be prescribed that decreases the amount of cystine in your urine to prevent cystine stones.