Kidney stones are hard deposits made of minerals and salts that form inside your kidneys or urinary tract. Stones form when the urine becomes concentrated, causing minerals to crystallize and stick together. These stones may stay in your kidneys or travel out of your body through the urinary tract. When a stone moves through a ureter, it generally causes severe pain and other symptoms. Kidney stones are also known as renal calculi.
Causes of kidney stones
The kidneys regulate the levels of fluid, minerals, salts, and other stuffs in the body. When the balance of these compounds changes, kidney stones may develop. The most common cause of change in balance is not drinking enough water. When you don’t drink adequate water, the urine becomes concentrated, causing the salts and other minerals in the urine to grow and stick together to form stones. Certain medical conditions can also affect the normal balance and cause stones to form. These stones are very small when they form, smaller than a grain of sand, but can grow slowly over time to an inch or larger. They may cause severe pain if they break loose and pass into the ureters, the narrow ducts leading to the bladder.
Types of kidney stones
There are different types of kidney stones, each made of different substances. Knowing the kind of kidney stone helps to know the cause and may give hints on how to decrease your risk of getting more stones. Types of kidney stones include:
- Calcium stones: Most kidney stones are calcium stones, generally in the form of calcium oxalate. A slighter percentage of calcium stones are made of calcium phosphate. Dietary factors and certain metabolic disorders increase your risk.
- Struvite stones: These stones are made of magnesium ammonium phosphate and are usually formed in response to an infection, such as a urinary tract infection. They can grow quickly and become quite large.
- Uric acid stones: These stones are made of uric acid, a waste product normally passed out of the body in the urine. These usually form due to low fluid intake, high protein diet, and gout.
- Cystine stones: These stones are caused by a buildup of the amino acid cystine. The tendency to form these stones is hereditary. Cystine stones grow rapidly and tend to recur.
Risk factors for developing kidney stones
- Family or personal history: If you have a family history of kidney stones, you are more likely to develop stones. And if you have had one or more kidney stones previously, you are at increased risk of developing another.
- Dehydration: Not drinking plenty water can increase your risk. When there is not sufficient water to weaken the uric acid (a component of urine), the urine becomes more acidic, which encourages the formation of kidney stones. People living in warm climates and those who sweat a lot may be at higher risk than others.
- Diet: Consuming a diet that is high in protein and sodium (salt) may increase your risk of kidney stones. Too much salt in your food increases the quantity of calcium your kidneys must filter and drastically increases your risk of stones.
- Obesity: Excess weight, a large waist size, and high body mass index (BMI) are factors linked to an increased risk of kidney stones. People with larger body sizes may excrete more calcium and uric acid into the urine, that increases the risk for stone formation.
- Digestive diseases and surgery: Long-lasting diarrhea, inflammatory bowel disease or gastric bypass surgery can cause changes in the digestive process that disturb your absorption of calcium and water, increasing the levels of stone-forming substances in your urine.
- Medical conditions: Your risk of kidney stones can increase with diseases and conditions, such as renal tubular acidosis, hyperparathyroidism, gout, urinary tract infections, high blood pressure and diabetes. Certain medications can also increase the risk of kidney stones.
Symptoms of kidney stones
Kidney stones generally do not produce symptoms until they pass into the ureter, the tube connecting the kidney and bladder. When kidney stones move through the urinary tract, they may cause:
- Acute pain in the side, back, abdomen, or groin
- Pain that comes in waves and varies in intensity
- Frequent need to urinate
- Reduced amount of urine excreted
- Pain during urination
- Blood in the urine
- Nausea and vomiting
- Fever and chills (if there is an infection)
- Small stones may pass without causing symptoms