Kidney stones

10 Min Read

What is it

Kidney stones (which doctors refer to as renal calculi) are one of the most common disorders of the urinary tract and also one of the most painful. The stones themselves are small, solid lumps composed of minerals and crystallized salts the most common being calcium in combination with oxalate or phosphate that separate from urine and build up in the urinary tract.

Stones can form anywhere in the urinary tract but typically develop on the inner surfaces of one or both kidneys over a period of time. Once formed, the stones sometimes travel into and through the ureter and it is this passage through the ureter that can cause the intense pain.

Stones vary greatly in size as minuscule as a grain of sand to as large as a golf ball. Tiny stones may cause no symptoms when they pass through the ureter. But when a large stone, or pieces of it, moves out of the kidney and enters the ureter, it produces severe, intermittent pain (renal colic) caused by the ureter contracting in order to squeeze the stone and urine through the tract. This pain continues until the stone eventually makes its way along the ureter to the bladder, at the front of the body.

It’s estimated that 1 in 10 American adults will develop kidney stones, with men outnumbering women three to one; more than 200,000 people are hospitalized annually with kidney stone pain. White people are more prone to kidney stones than blacks, and most stone attacks affect people over the age of 30. At least half of those suffering a kidney stone attack will have a recurrence at the rate of one every two or three years.


A kidney stone is usually asymptomatic until it is dis- lodged from the kidney and migrates into the ureter, a narrow tube connecting the kidney to the bladder. When that occurs, the primary symptom is pain, which typically begins in the back, just below the ribs. Waves of sharp pain occur every few minutes, and over the first few hours (or days) the pain will follow the path of the stone through the ureter. Men may experience pain in the testes and penis as the stone passes. Once the stone is passed, the pain stops. The following symptoms may also occur:

  • Bouts of nausea and/or vomiting.
  • An urge to urinate but an inability to pass normal amounts at one time.
  • Blood in the urine.
  • Fever and chills (if there is a concomitant infection).

What causes it

In most cases, the formation of kidney stones is unknown. The most common cause of the stones is linked to unexplained excessive absorption of calcium from the intestine, which results in increased calcium in the urine. Still, the role of this mineral in kidney stone formation remains unclear. For example, one Harvard study found, surprisingly, that men who consumed a calcium rich diet (containing more calcium than four glasses of milk a day) had a nearly 50 percent lower risk of developing kidney stones during the next four years than men who consumed less calcium than two glasses of milk a day.

A family history of kidney stones is considered an important risk factor, as are certain dis- orders. Recurrent urinary tract infections may create a chemical environment conducive to kidney stone development. High uric acid levels, sometimes associated with symptoms of gout, may also lead to the formation of uric acid stones. People with irritable bowel syndrome are also at increased risk of developing kidney stones. Bacterial infections account for about 10 percent of cases.

Living in a hot climate may also be a factor. It’s thought that hot weather causes increased sweat loss and reduced urine production; thus the urine contains a higher concentration of stone-producing calcium.

What if you do nothing

Most stones are small, and are passed out in the urine without notice or pain. Large kidney stones may stay in the kidney and cause no problems. When a large stone does enter the ureter, it can cause pain that may last up to 72 hours; the pain stops once the stone passes into the bladder. While you might require medicine to battle the pain, a stone commonly passes without causing any difficulties.

If a large stone can’t pass, though, it may block the flow of urine and cause ultimate kidney damage. To stop this, the stone need to be removed surgically.

Home remedies

Since 90 percent of all kidney stones are less than 5 millimeters in diameter, self-treatment typically consists of measures to promote their natural passage out of the body.

Relieve the pain

Over-the-counter pain relievers such as aspirin, ibuprofen, naproxen, and acetaminophen can bring temporary relief For more severe pain your doctor can prescribe stronger medications.

Flush the stone out

Drink at least three quarts of water a day to flush the small stone into the bladder. Drink even more when it’s hot outside. To be sure you are drinking enough, your urine should be almost colorless.


If possible, go for a walk. This movement may speed up the passage of the stone.

Trap the stone

Each time you urinate, do so through a piece of gauze or tea strainer to trap the stone when it passes. Give it to your physician for analysis to find its cause, which will help with more specific treatment. Most stones are made of complex salts of calcium, but stones composed of uric acid indicate you have a treat- able metabolic disorder.


Since the exact cause of kidney stone formation is not known, avoiding them is practically impossible. The following measures may help prevent or reduce painful incidences in many people predisposed to this malady. If you have a history of stones, though, talk to your doctor about the preventive measures you should take. Kidney stones are a complex problem, and no single piece of advice is appropriate for all sufferers.

Drink three quarts of water daily

Increase your intake in hot and humid weather.

Consider limiting oxalate-rich foods

The most common stones are made of calcium oxalate and it’s well known that some stone formers reduce their likelihood of a recurrence by cutting back on certain foods. If you have too much oxalate in your urine (determined by a urine test), your physician may recommend that you lower your intake of green leafy vegetables, spinach, rhubarb, black pepper, cheese, peanut butter, nuts, vitamin C, beer, tea, and chocolate. These foods have oxalic acid salts that bind with calcium ions and promote stone formation.

Assess your consumption of calcium-rich foods

It is well known that some stone formers do reduce their risk of recurrence when they cut down on calcium. Yet some people may actually increase their risk when they do this, according to a 1993 Harvard study. The most plentiful sources of calcium are dairy products, particularly milk, yogurt, and cheeses. Remember that treatment of stones should be individualized. so if you have a history of stones, consult your physician about dietary measures.

Consider reducing your protein intake

Some stones are specifically linked to certain kinds of protein in the diet, which leads to too much uric acid and calcium stone formation. Again, consult your physician. Changing the diet to help the body utilize calcium more efficiently or taking medicine to reduce uric acid may help prevent this type of stone.

Treat underlying urinary tract infections

People with chronic urinary tract infection often develop stones composed of struvite, which is a combination of magnesium, ammonium, and phosphate. Preventing urinary tract infection will prevent these struvite stones.

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