What Are Kidney Stones?
Kidney stones (also called nephrolithiasis or urolithiasis) are hard objects condensed from minerals and other chemicals in the urine. Usually, these waste products dissolve in urine, but when there is excess waste and insufficient liquid, solid crystals form and grow. When stones are tiny, they may be passed in the urine, but stones that are too big block the flow of urine in the kidney, ureter, the bladder, or the urethra, causing the pain of kidney stones.
There are four types of kidney stones:
- calcium oxalate,
- uric acid,
- struvite, and
Kidney stones are common, affecting 19% of men and 9% of women by the time they turn 70.
What Are Symptoms of Kidney Stones?
In some cases, kidney stones do not cause any symptoms. When symptoms of kidney stones occur, they may include:
- Can range from a mild ache to pain so intense it requires hospitalization
- Waves of severe pain (renal colic) can last 20 to 60 minutes
- Occurs in the flank (the side, between the ribs and the hip) or the lower abdomen, and can move toward the groin
- Pain can also be vague or feel like a stomach ache that doesn’t go away
- Blood in the urine (hematuria)
- Urine may appear pink or reddish
- Blood may not be visible but is seen when urine is examined under a microscope
- Passage of “gravel” or “sand,” which are multiple small stones in the urine
- Pain with urination
- Urinary urgency
- Nausea or vomiting
- Fever and chills
- Urine that smells bad or appears cloudy
What Causes Kidney Stones?
Causes of kidney stones include:
- Drinking too little fluid
- Eating food with too much salt or sugar (particularly fructose, such as that found in table sugar and high fructose corn syrup)
- Diets low in calcium
- Use of calcium supplements
- Diets high in animal proteins
- Diet with low levels of phytate (found in wheat, rice, rye, barley, and bean products)
- Frequent spinach consumption
- Too much or too little exercise
- Weight loss surgery
- Family history of kidney stones
- Certain medical conditions
How Are Kidney Stones Diagnosed?
Kidney stones are diagnosed based upon a patient’s symptoms, physical examination, and imaging tests.
Tests used to diagnose kidney stones include:
- Computed tomography (CT) scan
- "KUB x-ray'' (kidney-ureter-bladder x-ray)
- Blood tests
- Basic metabolic profile (BMP) which includes kidney function tests blood urea nitrogen (BUN) and creatinine
- Uric acid
- Pregnancy test
- 24-hour urine test
After the stone comes out of the body, either on its own or following surgical removal, it can be analyzed to help determine treatment.
What Is the Treatment for Kidney Stones?
Treatment of a kidney stone depends on the size and location of the stone, the type of stone, and the patient’s pain levels.
If the stone is small enough and the doctors believe it will pass, the patient’s pain is tolerable, and they can eat and drink, treatment at home may be suggested.
Home treatment for kidney stones includes:
- Pain management
- Medications to facilitate stone passage
- Straining the urine to retrieve the stone for testing once it passes
- Knowing what type of stone you have helps determine treatment to prevent future stones
Medical treatments for larger stones or severe symptoms include:
- Stronger prescription pain medications
- Intravenous (IV) fluids given in the hospital
- Stones larger than 9 or 10 millimeters usually do not pass on their own so a procedure is needed to break up or remove the stone
- Ureteroscopy uses a thin telescope passed through the urethra and bladder into the ureter and kidney to remove the stone or to break it into smaller pieces that can pass more easily
- Shock wave lithotripsy (SWL) involves directing high-energy shock waves toward the stone causing the stone to break into fragments that can be more easily passed in the urine
- Percutaneous nephrolithotomy (PNL) is a minimally invasive surgical procedure in which a small telescope is passed through the skin of the back and into the kidney to remove the stone
What Are Complications of Kidney Stones?
Complications of kidney stones include:
- Recurrent kidney stones
- Increased risk of developing chronic kidney disease
- Infection of the kidney (pyelonephritis)
How Do You Prevent Kidney Stones?
Recurrent kidney stones are common and there are some measures that can help prevent future stones, such as:
- Increased fluid intake
- Dietary changes
- Recommendations may be based on the type of kidney stone you have
- Reduce excess salt (sodium) in the diet, which includes sandwich meats, packaged meals, canned soups, and sports drinks
- Eat more fruits and vegetables to reduce urine acidity
- Eat less animal protein which increases urine acidity
- Lose weight if you are overweight but avoid a high-protein diet or crash diets
- Preventive medications may be prescribed to reduce the risk of developing future stones