Kidney stones is a small, solid deposits that form inside your kidneys. It may be as small as a grain of sand or as large as a pearl. Most kidney stones pass out of the body without help from a doctor. But sometimes a stone will not go away. If stones grow to sufficient size usually at least 3 millimeters (0.12 in) they can cause blockage of the ureter. This leads to pain, most commonly beginning in the flank or lower back and often radiating to the groin or genitals. This pain is often known as renal colic and typically comes in waves lasting 20 to 60 minutes. Passing kidney stones can be quite painful, but the stones usually cause no permanent damage. Depending on your situation, you may need nothing more than to take pain medication and drink lots of water to pass a kidney stone. In other instances, surgery may be needed. Your doctor may recommend preventive treatment to reduce your risk of recurrent kidney stones if you’re at increased risk of developing them again.
Types of Kidney Stones
Not all kidney stones are made up of the same crystals. The different types of kidney stones include:
- Calcium. Calcium stones are the most common. They can be made of calcium oxalate (most common), phosphate, or maleate. Vitamin C and spinach contain oxalate. Calcium-based kidney stones are most commonly seen in young men between the ages of 20 and 30.
- Uric Acid. This type of kidney stone is more common in men than in women. They can occur in people with gout or those going through chemotherapy.
- Struvite. This type of stone is found mostly in women with urinary tract infection. These stones can be quite large and cause urinary obstruction.
- Cystine. Cystine stones are rare. They occur in both men and women who have the genetic disorder cystinuria.
- Other. Medications like triamterene and acyclovir also can cause stones.
Kidney stones often have no definite, single cause, although several factors may increase your risk.
Kidney stones form when your urine contains more crystal-forming substances such as calcium, oxalate and uric acid, than the fluid in your urine can dilute. At the same time, your urine may lack substances that keep crystals from sticking together, creating an ideal environment for kidney stones to form.
Signs and Symptoms
Kidney stones are known to cause severe pain. Symptoms of kidney stones may not occur until the stone begins to move down the ureters. The severe pain is called renal colic. Pain may be located 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 is quite intense. People with renal colic tend to be restless. Other symptoms that can be present are:
- blood in the urine
- discolored or foul-smelling urine
Why Kidney Stones Can Be a Problem
Stones 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.
Sometimes stones block the flow of urine. This is called a urinary obstruction. Urinary obstructions can lead to kidney infection (pyelonephritis) and kidney damage.
Exams and Tests
The health care provider will perform a physical exam. The belly area (abdomen) or back might feel sore.
Tests that may be done include:
- Blood tests to check calcium, phosphorus, uric acid, and electrolyte levels
- Kidney function tests
- Urinalysis to see crystals and look for red blood cells in urine
- Examination of the stone to determine the type
Stones or a blockage can be seen on:
- Abdominal CT scan
- Abdominal/kidney MRI
- Abdominal x-rays
- Intravenous pyelogram (IVP)
- Kidney ultrasound
- Retrograde pyelogram
Treatment for kidney stones varies, depending on the type of stone and the cause.
Small stones with minimal symptoms
Most kidney stones won’t require invasive treatment. You may be able to pass a small stone by:
- Drinking water. Drinking as much as 2 to 3 quarts (1.9 to 2.8 liters) a day may help flush out your urinary system. Unless your doctor tells you otherwise, drink enough fluid mostly water to produce clear or nearly clear urine.
- Pain relievers. Passing a small stone can cause some discomfort. To relieve mild pain, your doctor may recommend pain relievers such as ibuprofen (Advil, Motrin, others), acetaminophen (Tylenol, others) or naproxen sodium (Aleve).
- Medical therapy. Your doctor may give you a medication to help pass your kidney stone. This type of medication, known as an alpha blocker, relaxes the muscles in your ureter, helping you pass the kidney stone more quickly and with less pain.
Kidney stones that can’t be treated with conservative measures either because they’re too large to pass on their own or because they cause bleeding, kidney damage or ongoing urinary tract infections may require more invasive treatment. Procedures may include:
- Using sound waves to break up stones. For certain kidney stones depending on size and location your doctor may recommend a procedure called extracorporeal shock wave lithotripsy (SWL). SWL uses sound waves to create strong vibrations (shock waves) that break the stones into tiny pieces that can be passed in your urine. The procedure lasts about 45 to 60 minutes and can cause moderate pain, so you may be under sedation or light anesthesia to make you comfortable. SWL can cause blood in the urine, bruising on the back or abdomen, bleeding around the kidney and other adjacent organs, and discomfort as the stone fragments pass through the urinary tract.
- Surgery to remove very large stones in the kidney. A procedure called percutaneous nephrolithotomy (nef-row-lih-THOT-uh-me) involves surgically removing a kidney stone using small telescopes and instruments inserted through a small incision in your back. You’ll receive general anesthesia during the surgery and be in the hospital for one to two days while you recover. Your doctor may recommend this surgery if SWL was unsuccessful or if your stone is very large.
- Using a scope to remove stones. To remove a smaller stone in your ureter or kidney, your doctor may pass a thin lighted tube (ureteroscope) equipped with a camera through your urethra and bladder to your ureter. 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 tube (stent) in the ureter to relieve swelling and promote healing. You may need general or local anesthesia during this procedure.
- Parathyroid gland surgery. Some calcium stones are caused by overactive parathyroid glands, which are located on the four corners of your thyroid gland, just below your Adam’s apple. When these glands produce too much parathyroid hormone (hyperparathyroidism), your calcium levels can become too high and kidney stones may form as a result. Hyperparathyroidism sometimes occurs when a small, benign tumor forms in one of your parathyroid glands or you develop another condition that leads these glands to produce more parathyroid hormone. Removing the growth from the gland stops the formation of kidney stones. Or your doctor may recommend treatment of the condition that’s causing your parathyroid gland to overproduce the hormone.
Proper hydration is a key preventive measure. Johns Hopkins Medicine recommends drinking six to eight glasses of water daily. You can substitute some glasses with ginger ale, lemon-lime soda, and fruit juice. Your doctor also may prescribe medications to help prevent the formation of calcium and uric acid stones.