Kidney stones may be composed of several substances. However, the four most common types of Kidney stones include calcium, struvite, uric acid and Cystine stones. Out of these the most commonly found stones are those composed of calcium, followed by struvite, uric acid and the least common are the Cystine stones.



Almost 80% of all kidney stones are made of calcium compounds; calcium oxalate and calcium phosphate. The extra calcium that is not used up in bone and muscle building and strengthening is passed into the blood that carried to the kidneys. The kidneys filter the blood of all impurities, along with this extra calcium. This extra calcium, in normal circumstances, dissolves in the urine and is flushed out of the body. However, if the kidneys do not carry out their functions optimally, the calcium remains in the kidneys and tends to clump together to form kidney stones. Certain other medical conditions such as sarcoidosis, hyperthyroidism, renal tubular acidosis, multiple myeloma, hyperoxaluria and some types of cancer increase the risk of calcium stones. If you have calcium stones your doctor may ask you to cut back on salt and sodium as they facilitate stone formation. Your dietician can help you make the required changes in your diet. Consult a registered doctor or dietician to determine if you need more or less calcium.

About 10% of all kidney stones fall into the Struvite stones category. Struvite stones are mainly composed of magnesium ammonium phosphate. The stones usually occur when the patient has repeatedly suffered from urinary tract infection. The bacteria involved in this infection leaves behind a deposit which is called urease. This deposit increases the urine PH, making it more alkaline and less acidic. This chemical environment encourages the forming of struvite stones. These "infection stones" are also known as stag horn calculi, if they grow large enough. Women are affected more than men because of their higher risk of urinary tract infections. Medical treatment, including antibiotics and removal of the stone, is usually needed for struvite stones.

Uric acid stones are about 5% of all the stones that occur. Uric acid stones are caused by the clumping together of uric acid crystals within the kidneys. This happens in patients who have a high percentage of uric acid in their blood stream. If the urine output is low, the uric acid absorbed out of the blood stays in the kidneys with a little amount being flushed out with the urine. A diet high in animal protein, such as red meat and high alcohol intake may trigger the formation of these stones. Uric acid stones are common in people who have Gout. Other causes of uric acid stones include chemotherapy for cancer, certain bone marrow disorders where blood cells are over-produced, and an inherited disorder called Lesch-Nyhan syndrome.

Cystine stones are the rarest. They make up only 1% of all kidney stones. The excess of the chemical Cystine in the urine results in the formation of these stones. They are more likely to develop in families with a condition called 'Cystinuria' which results in too much of Cystine in the urine. Medicine is available to prevent or dissolve these stones. However, if large, the removal of the stone may get difficult and painful.

The chemical make up of the stone goes a long way in helping to pave the way for more efficient and effective treatment in a lesser time frame. The reason for the development of a specific stone type may then be determined and eradicated. Similarly, the likelihood of the recurrence of these stones may be lessened.