Kidney stones usually form within the kidney, where urine collects before flowing into the ureter, the tube that leads to the bladder. Small kidney stones are able to pass out of the body in the urine — and may go completely unnoticed by you
Kidney stones usually form within the kidney, where urine collects before flowing into the ureter, the tube that leads to the bladder. Small kidney stones are able to pass out of the body in the urine — and may go completely unnoticed by you. But larger stones can irritate and stretch the ureter as they move toward the bladder, blocking the flow of urine and causing excruciating pain. Sometimes, a stone can be too large to pass into the ureter and can remain lodged in the kidney.
Why some people form kidney stones and others don’t is not always clear. Kidney stone disease is more common in young and middle-aged adults than in the elderly, and more prevalent in men than women. People living in hot climates are sometimes prone to kidney stones because they may become dehydrated more often than those in cooler climates, which concentrates the minerals in their urine and makes crystal formation easier. Medical evidence suggests that drinking too few fluids can increase the risk for forming kidney stones.
Most urinary stones are composed of calcium oxalate crystals — a kind of salt in the urine that’s difficult to dissolve. Uric acid is a less common cause of stones. If your urine is chronically infected with certain organisms, you can be prone to getting different types of kidney stones, as well.
Certain people are frequent “stone formers.” A person who has one stone has a 50% chance of developing another stone within the next 7 years.
Kidney stones may form when the normal balance of water, salts, minerals, and other substances found in urine changes. How this balance changes determines the type of kidney stone you have. Most kidney stones are calcium-type-they form when the calcium levels in your urine change.
Things that change your urine balance include:
- Not drinking enough water. When you don’t drink enough water, the salts, minerals, and other substances in the urine can stick together and form a stone. This is the most common cause of kidney stones.
- Medical conditions. Many medical conditions can affect the normal balance and cause stones to form. Examples include gout and inflammatory bowel disease, such as Crohn’s disease.
More commonly, kidney stones can run in families, as stones often occur in family members over several generations.
In rare cases, a person forms kidney stones because the parathyroid glands produce too much of a hormone. This leads to higher calcium levels and possibly calcium kidney stones.
Several risk factors (things that put you at risk) for kidney stones make it more likely that you will get them. Some of these things you can control, and others you cannot.
Risk Factors You Can Control
- Your diet. Diets high in protein, sodium, and oxalate-rich foods, such as dark green vegetables, increase your risk for kidney stones. If you think that your diet may be a problem, schedule an appointment with a dietitian and review your food choices.
- Being overweight. This can cause both insulin resistance and increased calcium in the urine, which can result in a greater risk for kidney stones.
- Medicine. Some medicines, such as acetazolamide (Diamox) and indinavir (Crixivan), can cause kidney stones to form.
Risk Factors You Can’t Control
- Age and gender.Men between the ages of 30 and 50 are most likely to get kidney stones.Postmenopausal women with low estrogen levels have an increased risk for kidney stones. Women who have had their ovaries removed are also at increased risk.
- Postmenopausal women with low estrogen levels have an increased risk for kidney stones, as are women who have had their ovaries removed.
- family history of kidney stones.
- A personal history of frequent urinary tract infections.
- Other diseases or conditions, such as Crohn’s disease, hyperparathyroidism, or gout.
- Intestinal surgery or gastric bypass surgery.
Symptoms of a Kidney Stone
Kidney stones form in the kidney. If they stay in the kidney, they typically do not cause pain. When they travel out of the body through the tubes of the urinary tract (including the ureters, which connect the kidney to the bladder, or the urethra, which leads outside the body)
The movement of kidney stones in the body may cause:
- No symptoms, if the stone is small enough.
- Sudden, severe pain that get