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Definition of Hyperoxaluria
Hyperoxaluria – excessive oxalate excretion in the urine. Oxalate is a natural chemical that enters the body through dietary sources such as vegetables, fruits, and grains. The liver also metabolizes oxalate. Researchers do not know what benefits the body derives from oxalate. However, in the body oxalate attracts calcium, creating the insoluble compound calcium oxalate.
About 80 percent of kidney stones are made of calcium oxalate. Deposits of calcium oxalate may also accumulate in tissues such as the kidneys, liver, heart, and bones, a circumstance known clinically as oxalosis.
Most hyperoxaluria is idiopathic (without a clearly identifiable cause). Doctors believe about 50 percent of people who have mild to moderate hyperoxaluria consume an abundance of foods high in dietary oxalate. In some people the binding between calcium and oxalate intensifies for reasons researchers do not understand though believe results from genetic factors.
Less commonly, hyperoxaluria occurs as an autosomal recessive genetic disorder that results in the absence of an enzyme the body requires to break down oxalate into soluble components that are more easily excreted. Genetic hyperoxaluria generally causes symptoms (typically kidney or bladder stones) in early childhood. Rarely, hyperoxaluria is a secondary complication of malabsorption disorders, such as short bowel syndrome and inflammatory bowel disease (ibd), that alter the gastrointestinal tract’s absorption of dietary calcium and oxalate.
Symptoms, Diagnosis and Diet
The most common symptoms are kidney stones (nephrolithiasis) or bladder stones (urolithiasis). The diagnostic path includes laboratory tests to measure the levels of oxalate in the urine and the blood, analysis of any stones, and family history. Dietary modifications (eating fewer foods with high oxalate content) are often treatment enough for mild idiopathic hyperoxaluria.
Other therapeutic approaches include medications to increase the ability of the urine to dissolve calcium and oxalate salts, magnesium and pyridoxine (vitamin B6) supplementation, and increasing water consumption to dilute the urine. Primary (genetic) hyperoxaluria typically results in renal failure by early adulthood with the only definitive treatment being kidney transplantation.
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