Struvite Vs. Oxalate Crystals

Kidney stones are a common and painful disorder of the urinary tract and are the cause of as many as 3 million doctors' visits in America each year. The stones (also called renal calculi) form from crystals of insoluble compounds that agglomerate in the urine inside the urinary tract. There are different compounds that can form kidney stones; two of these are calcium oxalate and struvite. Although the end effect is similar, calcium oxalate stones and struvite stones often result from different causes.

General Causes

• There are a variety of factors that can increase your chance of developing kidney stones. Several rare inherited diseases like renal tubular acidosis are linked to an increased risk, as is a family history of kidney stones. Gout, urinary tract infections, chronic bowel inflammation, and certain dietary imbalances can also cause or be linked to kidney stones in adults.

Incidence

• In the United States, calcium oxalate stones are by far the most common type. Only 10 to 15 percent of kidney stone cases involve struvite stones.

Urinary Tract Infections

• Struvite stones are composed of crystals of ammonium magnesium phosphate. Struvite dissolves readily in acidic solutions but is more insoluble in basic or neutral solutions. Certain species of bacteria can split urea, a compound in urine, thereby making the urine more alkaline or basic and creating the conditions for struvite crystals to form.

Diet and Stones

• While struvite stones typically form as a result of urinary tract infections, calcium oxalate stones are more closely linked to other conditions, and diet and hereditary factors often play major roles. An excess of calcium or of oxalate in the urine increases the chances that kidney stones will form. This excess may result from genetic disorders, from diet or from other diseases and conditions.

Preventive Measures

• According to the National Institute of Diabetes and Digestive and Kidney Diseases, an excess intake of vitamin D or of calcium-containing antacids can both contribute to the chances of developing calcium oxalate stones. Doctors typically recommend that patients who have developed stones in the past avoid foods high in oxalate, including rhubarb, spinach, beets, swiss chard, wheat germ, soybean crackers, peanuts, okra, chocolate and sweet potatoes. Doctors may also prescribe medicines to try to manage the level of calcium or the pH of your urine. Struvite crystals, on the other hand, result primarily from bacterial infections that increase urinary pH; doctors will generally test regularly for any signs of recurrence and may take additional steps to prevent repeated infections.