Kidney stones are medically known as renal stones (nephrolithiasis is the proper medical term, which literally means stones in the renal system). Approximately one in twenty people will develop kidney stones at some point in their lives. The stone/s may be present for many months to years without causing any symptoms, however, once the stone moves, or becomes enlarged, it can cause intense pain, which is colicky (comes and goes in waves) in nature, and thus, this particular kind of pain is referred to as renal colic.
Kidney stones are tiny calcifications inside the renal system which are formed when there is decreased urine production due to multiple reasons, and/or an excess of stone-forming substances in the urine. The following are the 4 main chemical types of kidney stones:
Calcium stones. These account for 75% of the stones. Many times, these stones form secondary to underlying disorders such as hyperactivity of the parathyroid gland (which regulates calcium metabolism in the body), or calcium leak in the kidneys. These patients are usually advised a low salt, low protein diet. Calcium is generally not restricted in patients with calcium stones.
Uric acid stones. These stones account for 6% of renal calculi. These are often times associated with low urine pH, high meat intake, and malignancies. Approximately 25% people with uric acid stones have underlying gout.
Struvite stones. Struvite stones make up 15% of renal calculi. They are associated with long term, multiple UTI infections with certain types of organisms. For such patients, underlying causes for the multiple UTIs should be sought out, as the stones will likely not be completely resolved until the UTIs are.
Cystine stones. Cystine stones are quite uncommon, and make up 2% of renal calculi. They arise due to defects in the kidneys in absorbing cystine. It is a breakdown product of soybean, beef, lamb, and other types of animal proteins.
SIGNS AND SYMPTOMS
Kidney stones often cause no pain while they are in the kidneys. But they can cause sudden, severe pain as they travel from the kidneys to the bladder. The pain is very characteristic in nature, called colicky pain, or renal colic. It typically travels from the flank to the groin, and comes in waves.
It may be associated with nausea, vomiting, and occasionally fever.
DIAGNOSIS AND MANAGEMENT
Pain with kidney stones is usually very severe, that a patient normally will visit the hospital. History of renal colic is typical. In addition to a good history, patients are required to submit a urine sample to check for microscopic blood and/or any signs of kidney infection ( called pyelonephritis; happens when a UTI ascends to the kidney). Patient will also undergo CT scan of the kidney, ureters and bladder, to diagnose the stone, and assert its position in the urinary system.
If a stone is < 4mm in size, it will normally pass by itself within a few days with urine. Pain relief is recommended with over the counter pain killers, and patients are generally called back in a few weeks to have repeat imaging done to make sure the stone has passed.
For larger stones, patients might be admitted and undergo extracorporeal shock wave lithotripsy (ESWL). ESWL is the commonest method of breaking a stone, which uses shock waves to break a kidney stone into small pieces. The bits can pass out of your body in your urine.
Other times, a doctor will need to remove the stone or place a small flexible plastic tube (called stent) in the ureter to keep it open while stones pass.
Patients with multiple kidney stones, or stones in both kidneys, or any other complications may undergo further testing to determine the cause, and will have a special treatment plan.
PREVENTING KIDNEY STONES
After you have had kidney stones, you are more likely to have them again. You can help prevent them by drinking plenty of water, enough so that your urine is light yellow or clear like water, about 8 to 10 glasses of water a day. You may have to eat less of certain foods. Your doctor may also give you medicine that helps prevent stones from forming.