Results of Long-Term Treatment with Orthophosphate and Pyridoxine in Patients with Primary Hyperoxaluria

Dawn S. Milliner, David M. Wilson, Lynwood H. Smith, Jeffrey T. Eickholt, Erik J. Bergstralh

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Background: The prognosis for patients with primary hyperoxaluria has been ominous, with the expectation of renal failure, poor results with transplantation, and early death. Methods: We studied the long-term effects of orthophosphate and pyridoxine therapy in 25 patients with primary hyperoxaluria who were treated for an average of 10 years (range, 0.3 to 26). Their mean age at the start of treatment was 12 years (median, 6; range, 0.5 to 32). We also studied the effect of orthophosphate and pyridoxine on urinary supersaturation with calcium oxalate, crystal inhibition using a seeded growth system, and crystal formation using scanning electron microscopy in 12 patients during three-day stays in the clinical research center. Results: The mean (±SD) glomerular filtration rate at the start of treatment was 91 ±26 ml per minute per 1.73 m2. The median decline in glomerular filtration rates was 1.4 ml per minute per 1.73 m2 of body-surface area per year. The actuarial survival free of end-stage renal disease was 96, 89, 74, and 74 percent at 5, 10, 15, and 20 years, respectively. Treatment with orthophosphate and pyridoxine reduced urinary supersaturation with calcium oxalate from 8.3 ±3.0 to 2.1 ±1.7 kJ per mole at 38 °C (P<0.001), increased the inhibition of calcium oxalate formation from 63 ±11 to 108 ±10 inhibitor units per 24 hours (P<0.001), and improved the crystalluria score from 2.6 ±0.3 to 0.6 ±0.1 (P<0.001). Conclusions: Treatment of patients with primary hyperoxaluria with orthophosphate and pyridoxine decreases urinary calcium oxalate crystallization and appears to preserve renal function., Primary hyperoxaluria is an autosomal recessive disorder caused by defects in hepatic enzyme systems important in the metabolism of glyoxylate, a major precursor of oxalate1. In type I primary hyperoxaluria, a deficiency or mistargeting of hepatic alanine-glyoxylate transaminase results in increased production of glycolate and oxalate25. In type II primary hyperoxaluria, deficiencies in glyoxylate reductase and glycerate dehydrogenase result in increased production of l-glyceric acid and oxalate6,7. The marked excess of oxalate in both disorders is eliminated primarily by renal excretion, leading to the formation of insoluble calcium oxalate in the urine, crystalluria, stone formation,…

Original languageEnglish (US)
Pages (from-to)1553-1558
Number of pages6
JournalNew England Journal of Medicine
Issue number23
StatePublished - Dec 8 1994

ASJC Scopus subject areas

  • General Medicine


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