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If the crystals that form the stones remain tiny enough, they can pass through without even being noticed.

More men tend to develop stones than women. But the number of women who get kidney stones has been increasing. Whites are more prone to kidney stones than are Blacks, Hispanics, and Asians. The prevalence of kidney stones rises dramatically as men enter their 40s and continues to rise into their 70s. For women, the prevalence of kidney stones peaks in their 50s. Kidney stones also tend to run in families. Once a person gets more than 1 stone, they are more likely to develop others.

The most common type of stone contains calcium plus either oxalate or phosphate. These chemicals are part of a person's normal diet and make up important parts of the body, such as bones and muscles.

Kidney disorders such as malformations or blockages, and metabolic disorders such as hyperparathyroidism, are also linked to stone formation. Genetic conditions may also play a role. Also, people with a rare hereditary disease called renal tubular acidosis have increased risk of developing kidney stones.

The pain often begins suddenly, when a stone moves in the urinary tract. This causes irritation or blockage. Typically, a person feels a sharp, cramping pain in the back and side, in the area of the kidney. Or they may feel pain in the lower belly (abdomen). Sometimes nausea and vomiting occur with this pain. Later, the pain may spread to the groin. Change of position doesn't improve the pain.

Fortunately, most stones can be treated without surgery. Most kidney stones can pass through the urinary system with plenty of water (2 to 3 quarts a day) to help move the stone along. In most cases, you can stay home during this process, taking pain medicine as needed. Your healthcare provider will likely ask you to save the passed stone(s) for testing. They can give you a device that's like a coffee filter. You can use it when peeing (urinating). It allows you to see the stones when you are done. Other minimally invasive methods are available to treat stones. Surgery is only needed in rare cases.

If you have stones that develop again and again, you should try to drink enough liquids—water is best—throughout the day to make at least 2 quarts of urine in every 24-hour period.

Extracorporeal shockwave lithotripsy (ESWL) is the most often used nonsurgical procedure to treat kidney stones. ESWL uses shockwaves that are created outside of the body. These shockwaves travel through the skin and body tissues until they hit the dense stones. They cause the stones to break into tiny pieces. The stones become sand-like and are easily passed through the urinary tract in the urine.