What Are Kidney Stones?
stones, or renal calculi, are solid masses made of crystals. Kidney stones usually
originate in your kidneys, but can develop anywhere along your urinary tract.
The urinary tract includes the kidneys, ureters, bladder, and urethra.
stones are known to be one of the most painful medical conditions. The causes
of kidney stones vary according to the type of stone.
Types of Kidney Stones
all kidney stones are made up of the same crystals. The different types of
kidney stones include:
stones are the most common. They can be made of calcium oxalate (most common),
phosphate, or maleate. Eating fewer oxalate-rich foods can reduce your risk of
developing this type of stone. High-oxalate foods include potato chips,
peanuts, chocolate, beets, and spinach.
type of kidney stone is more common in men than in women. They can occur in
people with gout or those going through chemotherapy. This type of stone
develops when urine is too acidic. A diet rich in purines can increase urine’s
acidic level. Purine is a colorless substance in animal proteins, such as fish,
shellfish, and meats.
type of stone is found mostly in women with urinary tract infections. These
stones can be large and cause urinary obstruction. These stones are caused by a
kidney infection. Treating an underlying infection can prevent the development
of struvite stones.
stones are rare. They occur in both men and women who have the genetic disorder
cystinuria. With this type of stone, cystine — an acid that occurs naturally in
the body — leaks from the kidneys into the urine.
Risk Factors for Kidney Stones
greatest risk factor for kidney stones is making less than one liter of urine
per day. This is why kidney stones are common in premature infants who have
stones are most likely to occur between the ages of 20 and
factors can increase your risk of developing a stone. Typically, Caucasians are more likely to have kidney
stones than African Americans. Sex also plays a role, with more men than women
developing kidney stones, according to the National Institute of Diabetes and Digestive and
Kidney Diseases (NIDDK). A history of kidney stones can increase
your risk, as does a family history of kidney stones.
risk factors include:
- high-protein, salt, or glucose diet
- hyperparathyroid condition
- gastric bypass surgery
- inflammatory bowel diseases that increase calcium
- taking medications such as diuretics,
anti-seizure drugs, and calcium-based antacids
Recognizing the Symptoms and Signs of a Kidney Stone
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.
symptoms of kidney stones can include:
- blood in the urine (red, pink, or brown urine)
- discolored or foul-smelling urine
- frequent need to urinate
- urinating small amounts of urine
In the case of a small kidney stone, you may not have any
pain or symptoms as the stone passes through your urinary tract.
Why Kidney Stones Can
Be a Problem
don’t always stay in the kidney. Sometimes, they pass from the kidney into the
ureters. Ureters are small and delicate, and the stones may be too large to
pass smoothly down the ureter to the bladder. Passage of stones down the ureter
can cause spasms and irritation of the ureters as they pass, which causes blood
to appear in the urine.
stones block the flow of urine. This is called a urinary obstruction. Urinary
obstructions can lead to kidney infection (pyelonephritis) and kidney damage.
Testing for and Diagnosing Kidney Stones
of kidney stones requires a complete health history assessment and a physical
exam. Other tests include:
- blood tests for calcium, phosphorus, uric acid,
- blood urea nitrogen (BUN) and creatinine to
assess kidney functioning
- urinalysis to check for crystals, bacteria,
blood, and white cells
- examination of passed stones to determine type
following tests can rule out obstruction:
- abdominal X-rays
- intravenous pyelogram (IVP)
- retrograde pyelogram
- ultrasound of the kidney (this is the preferred
- MRI of the abdomen and kidneys
- abdominal CT scan
How Kidney Stones Are Treated
is tailored according to the type of stone. 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.
treatment options include:
relief may require narcotic medications. The presence of infection requires
treatment with antibiotics. Other medications include:
- allopurinol for uric acid stones
- sodium bicarbonate or sodium citrate
- phosphorus solutions
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 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 (Percutaneous Nephrolithotomy)
are removed through a small incision in your back and may be needed when:
- the stone causes obstruction and infection or is damaging
- the stone has grown too large to pass
- pain cannot be controlled
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. A small cage is used to
snag the stone and remove it. The stone is then sent to the laboratory for
Kidney Stone Prevention
hydration is a key preventive measure. Johns Hopkins Medicine recommends drinking up to 12
glasses of water daily. Drinking more fluids increases
the amount of urine you pass, which helps flush the kidneys. The Mayo Clinic recommends passing 2.5 liters of urine a day. You can
substitute some glasses of water with ginger ale, lemon-lime soda, and fruit
oxalate-rich foods in moderation and reducing your intake of salt and animal
proteins can also lower your risk of kidney stones. Your doctor may prescribe
medications to help prevent the formation of calcium and uric acid stones. If
you’ve had a kidney stone, or you’re at risk for a kidney stone, speak with
your doctor and discuss the best methods of prevention.