What is a kidney stone?
A kidney stone is a hard mass of crystals that can form in the kidneys, ureters, bladder or urethra. Urine contains compounds that consist of calcium, sodium, potassium, oxalate, uric acid, and phosphate. If the levels of these particles get too high or if urine becomes too acidic or basic, the particles can clump together and crystallize. Unless the problem is addressed, the crystals will gradually grow over a few weeks, months, or even years, forming a detectable stone.
Calcium oxalate is the most common type of crystal to form this way and accounts for about 80% of kidney stones. Less common kidney stones are made of calcium phosphate or uric acid. A slightly different type of stone made of the minerals magnesium ammonium phosphate, or struvite, can be caused by a bacterial infection and even rarer stones can result from genetic disorders or certain medications. Kidney stones form inside the body but unfortunately, they are extremely painful to get out.
A kidney stone can go undetected until it starts to move. When a stone travels through the kidney and into the ureter, its sharp edges scratch the walls of the urinary tract. Nerve endings embedded in this tissue transmit excruciating pain signals through the nervous system and the scratches can send blood flowing into the urine. This can be accompanied by symptoms of nausea, vomiting, and a burning sensation while urinating. If a stone gets big enough to actually block the flow of urine, it can create an infection or backflow, and damage the kidneys themselves. But most kidney stones do not become this serious or even require invasive treatment. Masses less than five millimeters in diameter will usually pass out of the body on their own. A doctor will often simply recommend drinking large amounts of water to help speed the process along, and maybe taking some pain killers.
If the stone is slightly larger, medications like alpha-blockers can help by relaxing the muscles in the ureter and making it easier for the stone to get through. Another medication called potassium citrate can help dissolve the stones by creating less acidic urine. For medium-sized stones up to about ten millimeters, one option is pulverizing them with soundwaves. Extracorporeal shock wave lithotripsy uses high-intensity pulses of focused ultrasonic energy aimed directly at the stone. The pulses create vibrations inside the stone itself and small bubbles jostle it. These combined forces crush the stone into smaller pieces that can pass out of the body more easily. But zapping a stone with sound does not work as well if it is simply too big. So sometimes, more invasive treatments are necessary. A rigid tube called a stent can be placed in the ureter to expand it. Optical fibers can deliver laser pulses to break up the stone. Stones can also be surgically removed through an incision in the patient’s back or groin.
What are the types of kidney stones?
Many people think there is only one type of kidney stone. Doctors break down kidney stones into types, and it is important because which kind you have could affect the treatment you get. They include:
- Cystine stones: This is the least common type. Once you get a cysteine stone, there is a chance that you may have one again. You inherit the possibility of getting them from your parents, both of whom would have to have the same type of genetic mutation.
- Calcium stones: Calcium oxalate stones are the most common type of kidney stone. A diet high in salt (sodium) causes calcium to build in your urine. Too much calcium in your urine can lead to new stones. It can also cause your bones to weaken.
- Struvite stones: struvite stones are a type of hard mineral deposit that can form in your kidneys. Stones form when minerals like calcium and phosphate crystallize inside your kidneys and stick together. Struvite is a mineral that’s produced by bacteria in your urinary tract, can cause you to have this kind of stone.
- Uric acid stones: Eating a large amount of Red meat, organ meats, and shellfish can cause uric acid to build up in the urine and eventually form stone either with or without calcium. Risk factors include gout, diabetes, and chronic diarrhea.
What are the causes of kidney stones?
Kidneys filter blood by removing waste from it in the form of urine. Urine consists of water, urea, uric acid and ions like calcium, sodium, oxalate, and potassium. However, when some of these constituents such as uric acid, calcium and oxalate ions increase in the urine and they bond together forming kidney stones or renal calculi. Following are some of the most common causes of kidney stones.
- Lack of Water: The leading cause of kidney stones is a lack of water in the body. Stones are commonly found in individuals who drink less than the recommended eight to ten glasses of water a day. When there is not enough water to dilute the uric acid, a component of urine, the urine becomes more acidic. An excessively acidic environment in urine can lead to the formation of kidney stones.
- Sodium: You mainly get this through table salt. It can raise your chances of getting several types of kidney stones. So watch out for salty snacks, canned foods, packaged meats, and other processed foods.
- Animal Protein: Another kind of kidney stone forms when your pee is too acidic. Red meat and shellfish can make uric acid in your body rise. This can collect in the joints and cause gout or go to your kidneys and make a stone. More importantly, animal protein raises your urine’s calcium level and lowers the amount of citrate, both of which encourage stones.
- Diet: What you eat can play a big role in whether you get one of these stones. The most common type of kidney stone happens when calcium and oxalate stick together when your kidneys make urine. Oxalate is a chemical that’s in many healthy foods and vegetables. Your doctor may tell you to limit high oxalate foods if you have had this type of stone before. Examples include spinach, rhubarb, grits, and bran cereal. You may have heard that drinking milk can bring on kidney stones. That is not true. If you eat or drink calcium-rich foods like milk and cheese and foods with oxalate at the same time, it helps your body better handle the oxalate. That’s because the two tend to bind in the gut instead of in the kidneys, where a stone can form.
- Medications: Some medications can cause stones to include:
- certain antibiotics, including ciprofloxacin and sulfa antibiotics
- some drugs to treat HIV and AIDS
- certain diuretics used to treat high blood pressure. But some thiazide-type diuretics actually help prevent stones.
What are the symptoms of kidney stones?
Kidney stones are known to cause severe pain. Symptoms of kidney stones may not occur until the stone begins to move down the ureters. This severe pain is called renal colic. You may have pain on one side of your back or abdomen. In men, pain may radiate to the groin area. 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:
- blood in the urine (red, pink, or brown urine)
- discolored or foul-smelling urine
- frequent need to urine
- urinating small amounts of urine
In the case of small kidney stone, you may not have any pain or symptoms as the stone passes through your urinary tract.
What are the diagnostic tests for kidney stones?
If your doctor suspects you have a kidney stone, you may have diagnostic tests and procedures, such as:
- Blood testing: Blood tests may reveal too much calcium or uric acid in your blood. Blood test results help monitor the health of your kidneys and may lead your doctor to check for other medical conditions.
- Urine testing: The 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.
- Imaging: Imaging tests may show kidney stones in your urinary tract. Options range from simple abdominal X-rays, which can miss small kidney stones, to high-speed or dual energy computerized tomography (CT) that may reveal even tiny stones. Other imaging options include an ultrasound, a noninvasive test, and intravenous urography, which 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.
What are the treatment options for kidney stones?
Treatment for kidney stones varies, depending on the type of stone and the cause. Urine can be strained and stones collected for evaluation. Drinking six to eight glasses of water a day increases urine flow. People who are dehydrated or have severe nausea and vomiting may need intravenous fluids.
Other treatment options include:
- Medication: Pain relief may require narcotic medications. The presence of infection requires treatment with antibiotics. Other medications include:
- Allopurinol (Zyloprim) for uric acid stones
- Thiazide diuretics to prevent calcium stones from forming
- Sodium bicarbonate or sodium citrate to make the urine less acidic
- Phosphorous solutions to prevent calcium stones from forming
- Ibuprofen (Advil) for pain
- Acetaminophen (Tylenol) for pain
- Naproxen sodium (Aleve) for pain
- Lithotripsy: Extracorporeal shock wave lithotripsy uses sound waves to break up large stones so they can more easily pass down the ureters into your bladders. This procedure can be uncomfortable and may require light anesthesia. It can cause bruising on the abdomen and back and bleeding around the kidney and nearby organs.
- Tunnel Surgery: A surgeon removes the stones through a small incision in your back. A person may need this when;
- The stone causes obstruction and infection or is damaging the kidneys
- The stone has grown too large to pass
- Pain can’t be managed
- Ureteroscopy: when a stone is stuck in the ureter or bladder, your doctor may use an instrument called a ureteroscope to remove it. A small wire with a camera attached is inserted into the urethra and passed into the bladder. The doctor then uses a small cage to snag the stone and remove it. The stone is then sent to the laboratory for analysis.
How to prevent kidney stones?
Rather than having to undergo treatment, it is best to avoid kidney stones in the first place when possible. It can be especially helpful to drink more water since low fluid intake and dehydration are major risk factors for kidney stone formation. Depending on the cause of the kidney stones and an individual’s medical history, changes in the diet or medications are sometimes recommended to decrease the likelihood of developing further kidney stones. If one has passed a stone, it can be particularly helpful to have it analyzed in a laboratory to determine the precise type of stone so specific prevention measures can be considered.
People who have a tendency to form calcium oxalate kidney stones may be advised to limit their consumption of foods high in oxalates, such as spinach, rhubarb, Swiss chard, beets, wheat germ, and peanuts. Also drinking lemon juice or lemonade may be helpful in preventing kidney stones.
You may have heard the old line about kidney stones: these too shall pass. Better yet, don’t get them in the first place. They are easier to avoid than you might think. Genes can play a role, too. Forty percent of the people who get kidney stones have relatives who have them, too. With the right foods, plenty of water, and proper medication, you can lower your chances of kidney stones.