(Renal Colic; Renal Lithiasis; Nephrolithiasis; Renal Calculi)
Kidney stones – Definition
Kidney stones are pieces of a stone or crystal-like material in the urine. These stones form inside the kidneys or other parts of the urinary tract. The kidneys remove waste (in the form of urine) from the body. They also balance the water and electrolyte content in the blood by filtering salt and water.
There are several types of kidney stones:
- The most common type has mostly calcium along with oxalate or phosphate.
- Others types contain uric acid, struvite, and/or cystine.
Kidney stones – Causes
Some of the known causes include:
- Chemotherapy (ie, uric acid stone)
- Too much oxalate in urine (hyperoxaluria)
- Too little magnesium in urine (hypomagnesemia)
- Too much calcium in the urine (hypercalciuria)
- Too much calcium in the blood (hypercalcemia)
- Too little citrate in the urine (hypocitraturia)
- Bacteria around which a stone can form
- Too much uric acid in the urine (hyperuricuria, gout)
- Bacteria that produce enzymes that increase the amount of ammonia and struvite in the urine
- Inherited abnormality in the way the body handles cystine
- Certain medications (such as indinavir)
- Foreign bodies in the urinary tract, such as stents or catheters
- Retention of urine
Kidney stones – Risk Factors
Risk factors that can increase your chance of developing kidney stones include:
- Race: White
- Sex: male
- Age: 20 to 50 years old
- Geographic location (residents of the Southeast United States have an increased risk)
- Family members who have had kidney stones or gout
- Previous kidney stones
- Taking excess doses of calcium supplements or vitamin C
- Other medical conditions, including:
- Kidney disease
- Overactive parathyroid
- Chronic diarrhea
- Ulcerative colitis
- Crohn’s disease
- Urinary tract infections
- Immobility, paralysis, being bedridden
- Medications, including some AIDS medications, chemotherapy drugs, diuretics, and antacids
- Previous intestinal bypass surgery
- Reduced fluid intake or increased fluid loss in hot weather ( dehydration)
- Urinary tract obstruction or failure to empty the bladder
- Foreign material in the urinary tract (eg, catheter)
Kidney stones – Symptoms
Occasionally, kidney stones do not cause symptoms. They leave the body in the urine. The condition, though, can cause severe pain.
- Sharp, stabbing pain in the mid-back that may occur every few minutes and last from 20 minutes to one hour
- Pain in the lower abdomen and groin area, labia, or testicles
- Nausea, vomiting, or diarrhea
- Blood in the urine
- Frequent urge to urinate
- Burning pain during urination
- Urinary tract infection
Kidney stones – Diagnosis
The doctor will ask about your symptoms and medical history. A physical exam will be done.
Tests may include:
- Your doctor may order tests to gather information about your urine such as:
- 24-hour urine
- Urine culture
- Blood tests
- Your doctor may need detailed pictures of your kidneys and urinary system. These can be made with:
- Spiral CT scan
- Intravenous pyelogram (IVP) (less commonly used today)
Kidney stones – Treatment
Treatment depends on the size and location of the kidney stone. Treatment may include:
For small kidney stones, drinking at least two or three quarts of water a day helps the body pass the stone in the urine. The doctor may provide a special cup to catch the stone when it passes so it can be analyzed. If you are having a hard time keeping fluids down, you may need to be hospitalized to receive fluids in your vein.
Medications and Nerve Stimulation
Your doctor may recommend that you take pain medication. You may need medication that is given in the vein or in the muscles.
Certain medicine used to treat high blood pressure (eg, calcium channel blockers and alpha blockers) may help your body pass kidney stones.
Surgery may be needed if the stone is:
- Very large or growing larger
- Causing bleeding or damage to the kidney
- Causing infection
- Blocking the flow of urine
- Unable to pass on its own
Types of surgery include:
- Stent placement — used to allow urine to pass
- Ureteroscopy and stone basketing or laser lithotripsy — a camera is used to locate the stone
- Stone basketing — a tiny basket is used to remove the stone
- Laser lithotripsy — the stone is broken into smaller pieces with a laser if it is too large to remove
- Extracorporeal shock wave lithotripsy (ESWL) — uses shock waves to break up stones that are too large to pass
- Percutaneous nephrolithotomy — uses a scope placed through a small tube in the back to remove a large stone
- Lithotomy — open surgery to remove a stone (rarely used now)
If you are diagnosed as having kidney stones, follow your doctor’s instructions.
Kidney stones – Prevention
Once you have formed a kidney stone, you are more likely to form another. Here are some steps to prevent this condition:
- Drink plenty of fluids, especially water.
- Talk to your doctor about what diet is right for you. Depending on the type of stone you have, you may be told to:
- Avoid apple and grapefruit juices.
- Drink more cranberry juice.
- Avoid foods high in oxalate, such as spinach.
- Eat less meat, fish, and poultry. These foods increase urine acidity.
- Decrease your sodium intake (especially if you have calcium stones).
- Increase your intake of magnesium.
- Drink lemonade daily.
- Increase your fiber intake.
- Lose weight.
- If you have an enlarged parathyroid gland, you may need to have it removed surgically.
- Medicines may include:
- Drugs that control the amount of acid in the urine
- Allopurinol or sodium cellulose phosphate — to treat urine high in calcium
- Hydrochlorothiazide (a diuretic) — to treat urine high in calcium
- Thiola — to reduce the amount of cystine in the urine