A kidney stone is a hard mass that develops when crystals separate from urine and build up on the inner surfaces of the kidney. Stones develop in the kidney, but they may break loose and move through the ureter, bladder or urethra. Small stones pass through with little discomfort, but if they continue to build up and grow, this can cause intense pain.
The first symptom of a kidney stone is generally sharp, cramping pain in the back and side near the kidney or in the lower abdomen. The pain begins when a stone moves into the urinary tract, causing blockage and irritation. Nausea and vomiting may occur, and the pain may spread to the groin and genital areas. As a stone grows larger or continues to move through the urinary tract, blood may appear in the urine and you may feel the need to urinate more often or experience a burning sensation while urinating. Other symptoms include fever, loss of appetite, profuse sweating, and diarrhea or constipation.
In addition to causing severe pain, a lodged stone can block the flow of urine, causing wastes to back up into the kidneys. Such a condition must be corrected swiftly, either by surgically removing the stone or by nonsurgical medical procedures that break it up and allow it to pass naturally out of the body. If immediate action is not taken, serious kidney damage and related medical problems can result.
There are several different types of kidney stones, and each type contains various combinations of chemicals. The most common type of kidney stones contains calcium combined with either oxalate or phosphate. Another type of stone, called a struvite, is caused by infection in the urinary tract. Uric acid stones and cystine stones are the least common types.
Kidney stones are most commonly caused by not drinking enough water. They can also be caused by various diseases and disorders, and are more likely to develop in people with a family history of kidney stones. Urinary tract infections, kidney disorders and metabolic disorders such as hyperparathyroidism can lead to stone formation. Also, people with rare hereditary diseases, including renal tubular acidosis, cystinuria and hyperoxaluria, can develop kidney stones.
Other causes of stone formation include hyperuricosuria, gout, excess intake of vitamins C or D, and blockage of the urinary tract. Some diuretics and antacids could cause stones by increasing the amount of calcium in the urine.