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Stone Issue

Kidney stones are crystals of dissolved minerals in urine which are found inside the urinary system. They vary in sizes from as small as a grain of sand to as large as a golf ball. They are formed from the dissolved minerals in urine. As the kidney produces urine and flushes the urinary system, there is a tendency for the stones to move and to pass out through the urinary tract.

Sometimes, when the crystals or stones become too large (about 2–3mm), they will obstruct the urine stream and cause acute pain during urination. As the stone rubs against the inner lining of the urinary tract, it can damage the tract and cause blood to flow into the urine. The injured site can become a nidus (or catalyst) for recurrent urinary infection. At times, the stones can cause kidney damage and failure due to recurrent infection and obstruction.


The occurrence of kidney stones run in the family. This means genetic defect is one of the causes of urinary stone formation. One way of looking at this is, as the kidney filters and processes blood into urine, defects in the processing result in high concentrations of stone forming minerals like calcium, oxalate and uric acid. These mineral deposits accumulate over time to become kidney stones. The defective kidney may also cause too low a concentration of stone preventing minerals like citrates.

About 90% of urinary stones are mixed stones with the commonest minerals being calcium and oxalate. In minority of cases or about 10% of the time, we will find pure uric acid stones.

In calcium-based stones, treatment using shockwaves or holmium laser technology would remove the stones efficiently. These treatments shatter the stones into fine fragments that can then be flushed out safely during urination.

To date, there is no known medication that can dissolve calcium urinary stones. On the other hand, pure uric acid stones can be treated with oral medication, with a good possibility of dissolving them if there is no obstruction and there is good kidney function.

In urinary stone management, removal of the stones as well as prevention of recurrence are equally important. In select individuals, we can lower the chance of stone recurrences with tailored dietary changes according to one’s chemistry. A thorough checkup and close consultation with a kidney specialist is necessary to ensure a proper and effective plan.

Dr Michael Wong

Medical Director & Senior Consultant Urologist
FAMS (Urology), FICS (USA), FRCS (Edinburgh),
M Med (Surgery), MBBS (S’pore)

Dr Michael Wong is a Senior Consultant Urologist who is internationally recognized for his surgical expertise and academic contribution to the field of Urology, in particular the subspecialized field of minimally invasive Endourology.

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