Types of Kidney Stones

Calcium oxalate kidney stones:

Majority (75 to 80%) of kidney stones are composed of calcium oxalate crystals. Some factors can promote precipitation of calcium oxalate crystals present in urine in kidney, such as increased concentration of calcium oxalate (more than urine can dilute). Intake of low calcium in diet (contrary to common logic) is associated with increased incidence of calcium oxalate crystal formation according to current evidence. Oxalate crystals present in food binds to calcium present in diet and prevent absorption of oxalates, but in case of low dietary calcium intake less calcium is available to bind to oxalates and as a result there is increased absorption of oxalates into blood stream. Oxalates after absorption, get excreted in urine by kidneys and result in precipitation of oxalate crystals and formation of stones.

Uric acid kidney stones:

Approximately 5-10% of kidney stones are made of uric acid crystals. Uric acid stones are more common among obese individuals. Uric acid stones occur when there is hyperuricosuria (increased uric acid level in urine) with or without increase in blood uric acid level.

Uric acid stones are more common if urine is highly acidic (due to acid/base imbalance) for prolonged period of time, as acidic urine is responsible for precipitation of uric acid in urine. Uric acid stones can be diagnosed by persistent acidic urine, presence of crystals of uric acid in fresh urine sample and presence of radiolucent stone.

Other types of kidney stones:

There are several less common types of kidney stones such as calcium phosphate stones, cystine stones, and struvite stones (composed of magnesium, ammonium and phosphate) etc.

Calcium phosphate stones generally occur in renal tubular acidosis and hyperparathyroidism.

Cystine stones occur in patients suffering from cystinuria or presence of cystine in urine (an uncommon metabolic disorder).

Approximately 10-15% of kidney stones are struvite stones, which are also called infection stones (as struvite stones are always associated with urinary tract infection), urease stones or triple-phosphate stones. Struvite stones are associated with urea splitting bacteria, such as Proteus mirabilis, which split urea into ammonia and makes condition favorable for struvite stone formation.

Use of some medication also may cause increased risk of formation of kidney stones such as, indinavir, sulfadiazine, triamterene etc. due to deposition/precipitation of crystals of these medications.

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  • How to prevent Kidney Stone Formation? | mayamclistr
    February 27, 2011 - 9:18 am

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