Disorders of oxalate metabolism

Oxalate is a useless metabolic endproduct, formed as an unfortunate byproduct of the metabolism of glyoxylate and ascorbate. When formed it is excreted in the urine where it constitutes a hazard because of the insolubility of its calcium salt. In the majority of patients with calcium oxalate stones the urinary excretion of oxalate is normal. Reviewed herein are the acquired and genetic disorders associated with excessive oxalate excretion, in particular primary hyperoxaluria types I (glycolic aciduria) and II (glyceric aciduria). The demonstration of specific enzyme defects associated with these diseases has clarified the pathogenesis of oxalate production. Although rare, these diseases are important since they most frequently lead to early death from renal failure. Newer approaches to treatment are therefore being pursued; if successful, they might also find application in the treatment of patients with idiopathic calcium oxalate nephrolithiasis.