Numerous dissolved minerals and salts are found in urine. When your urine contains a high concentration of these minerals and salts, stones can form. Kidney stones can start out small, but they can grow to fill the kidney’s inner hollow structures. Some kidney stones remain in the kidney and cause no problems. Kidney stones can sometimes travel down the ureter, the tube between the kidney and the bladder. If the stone reaches the bladder, it can be eliminated through urine. If the stone becomes lodged in the ureter, it obstructs the kidney’s urine flow and causes pain.

The Urinary and Kidney System

The kidneys are fist-sized organs that regulate fluid and chemical levels in the body. One kidney is located on each side of the spine behind the liver, stomach, pancreas, and intestines in the majority of people. Kidneys in good health filter blood and excrete waste as urine. They regulate the blood levels of sodium, potassium, and calcium.

Kidneys, ureters, and the bladder comprise the urinary tract. The urinary system produces, transports, and stores urine. The kidneys produce urine from water and waste from the body. The urine then travels down the ureters and is stored in the bladder. Urine exits the body via the urethra.

Renal calculi are formed in the kidney. Some kidney stones migrate into the ureter. Ureters are tubes connecting the kidneys and bladder. When a kidney stone migrates to the ureter, it is referred to as a ureteral stone.

What Constitutes Kidney Stones?

There are many different types and colors of kidney stones. It depends on the type of stone you have as to how you treat them and prevent new ones from forming.

Calcium stones (80 percent of stones)

Calcium kidney stones are the most prevalent type. Two kinds of calcium stones exist: calcium oxalate and calcium phosphate. Calcium oxalate is the most common type of calcium stone by a wide margin. Some individuals have excessive calcium in their urine, which increases their risk for calcium stones. Even with normal calcium levels in the urine, calcium stones can form due to other causes.

Uric acid crystals (5-10 percent of stones)

Uric acid is a byproduct of chemical reactions within the body. Crystals of uric acid do not dissolve well in acidic urine and will instead form uric acid stones. • Obesity • Chronic diarrhea • Type 2 diabetes (high blood sugar) • Gout • Diet high in animal protein and low in fruits and vegetables

Struvite/infection calculi (10 percent of stones)

Struvite stones are a rare variety of stone. These stones are caused by persistent urinary tract infections (UTIs). Certain bacteria make urine less acidic and more alkaline or basic. In alkaline urine, magnesium ammonium phosphate (struvite) crystals form. These stones are typically large and branching, and they grow very rapidly.

People with chronic UTIs, such as those with long-term tubes in their kidneys or bladders, or those with poor bladder emptying due to neurologic disorders (paralysis, multiple sclerosis, and spina bifida) have the greatest risk for developing these stones.

Cystine stones (less than 1 percent of stones)

Cystine is an amino acid found in some foods; it is one of the protein’s building blocks. Cystinuria (excess cystine in the urine) is an uncommon genetic metabolic disorder. This condition occurs when the kidneys fail to reabsorb cystine from the urine. High levels of cystine in the urine result in the formation of stones. Typically, cystine stones begin to form during childhood.

Symptoms

Kidney stones frequently cause no symptoms and can go undiagnosed. When a kidney stone leaves the kidney, it travels through the ureter to the bladder. Stones frequently become lodged in the ureter. When a kidney stone obstructs the flow of urine out of the kidney, it can cause the kidney to swell (hydronephrosis), which is often extremely painful.

• Sharp, cramping pain in the back and sides, which frequently moves to the lower abdomen or groin. Some women claim that the pain is worse than labor pains. Frequently, the pain begins suddenly and comes in waves. It can appear and disappear as the body attempts to eliminate the stone.
• An overwhelming need to urinate.
• Frequent urination or a burning sensation during urination.
• Urine that is dark or red due to the presence of blood. Red blood cells are sometimes so rare in urine that they cannot be seen with the naked eye.
• Nausea and nausea.
• Men may experience pain at the tip of the penis.

Causes

Low Urine Volume

A significant risk factor for kidney stones is a persistently low urine volume. Low urine volume may result from dehydration (loss of body fluids) caused by strenuous exercise, working or living in a hot environment, or insufficient fluid intake. Low urine volume results in concentrated, dark-colored urine. There is less liquid in concentrated urine to keep salts dissolved. Increasing fluid intake will dilute the concentration of salts in urine. This may reduce your risk of developing kidney stones.

Adults who form stones should consume enough fluid each day to produce at least 2.5 liters (2/3 gallon) of urine. This will require approximately 3 liters (100 ounces) of fluid intake per day. Although water is likely the best fluid to consume, what is most important is consuming sufficient fluids.

Diet

Diet can also affect the likelihood of developing kidney stones. High calcium levels in the urine are one of the most prevalent causes of calcium kidney stones. High calcium levels in the urine may result from the way your body processes calcium. It is not always related to calcium intake. Rarely does reducing the amount of calcium in your diet prevent the formation of stones. Studies have shown that restricting calcium intake is detrimental to bone health and may increase the risk of kidney stones. Generally, health care providers do not recommend restricting calcium intake in order to reduce urine calcium levels. However, calcium intake should not be excessive.

Instead of reducing calcium intake through diet, your healthcare provider may attempt to lower calcium levels in your urine by decreasing your sodium (salt) intake. The consumption of excessive salt is a risk factor for calcium stones. This is because excessive salt levels in the urine prevent calcium from being reabsorbed back into the bloodstream. Dietary salt restriction decreases urine calcium, thereby decreasing the likelihood of calcium stone formation.

Since oxalate is a component of the most common type of kidney stone (calcium oxalate), consuming oxalate-rich foods can increase the risk of developing these stones.

A diet rich in animal proteins, such as beef, fish, chicken, and pork, can increase acid levels in the body and urine. High acid levels facilitate the formation of calcium oxalate and uric acid stones. Additionally, the breakdown of meat into uric acid increases the likelihood of both calcium and uric acid stones forming.

Bowel Disorders

Certain bowel disorders that cause diarrhea (such as Crohn’s Disease or ulcerative colitis) and surgeries (such as gastric bypass surgery) can increase the risk of developing calcium oxalate kidney stones. Diarrhea may result in significant fluid loss, thereby decreasing urine volume. Additionally, your body may absorb excessive oxalate from the intestine, resulting in elevated oxalate levels in your urine. Low urine volume and high urine oxalate levels can both contribute to the formation of calcium oxalate kidney stones.

Obesity

Stones are a risk associated with obesity. Obesity may alter the acid levels in urine, leading to the formation of kidney stones.

Medical conditions

Some medical conditions increase the likelihood of developing kidney stones. The abnormal growth of one or more parathyroid glands, which regulate calcium metabolism, can result in high blood and urine calcium levels. This could result in kidney stones. Another condition known as distal renal tubular acidosis, which involves an accumulation of acid in the body, can increase the risk of calcium phosphate kidney stones.

Some rare, inherited disorders can also increase the likelihood of certain types of stones. Cystinuria, in which there is an excess of the amino acid cystine in the urine, and primary hyperoxaluria, in which the liver produces an excess of oxalate, are examples.

Medication

Some medications, calcium supplements, and vitamin C supplements may increase the risk of developing kidney stones. Inform your healthcare provider of every medication and supplement you take, as these may affect your risk of developing kidney stones. Do not stop taking any of these unless instructed to do so by your doctor.

Family ancestry

If you have a parent or sibling with a history of kidney stones, your risk of developing them is significantly increased.