Kidney stones are abnormal, hard, crystalline mineral materials which form inside the kidneys. Kidney stones are also known as renal calculi or nephrolithiasis. The condition of having stones in the urinary tract is referred to as urolithiasis, and if the stone is present in ureters it is known as ureterolithiasis.
The size of kidney stones can be as small as grains of sand, the size of a pea, a marble or even larger. The stones can be asymptomatic and may pass out of the body in urine without causing discomfort or it can cause excruciating, cramping pain in the groin, lower back or abdomen. Kidney stones can often cause of blood in the urine (haematuria).
There are several types of kidney stones and the type of stone formed depends on the causative factor. The four common types of stone are:
- Calcium stones: These are the most common type of stone and tend to occur more often in men than in women. They appear mostly between ages 20 – 30 and have a tendency to recur. Calcium precipitates with other substances such as oxalate (the most common substance), phosphate, or carbonate to form stones. Certain foods such as dark green vegetables, nuts, and chocolates contain high amount of oxalate. The risk of formation of calcium oxalate stones is increased in case of diseases of the small intestine.
- Cystine stones: These stones form in people who suffer from cystinuria. This disorder tends to runs in families –so if you have cystine stones, your children are also at risk of developing cystine stones. These stones can affect both men and women.
- Struvite stones: These stones occur mostly in women who have urinary tract infection. The stones tend to become very large which can block the kidney, ureter, or bladder.
- Uric acid stones: These are found more often in men than in women. People with gout or on chemotherapy are at higher risk of developing uric acid stones.
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