Primary hyperoxaluria Type 1: organic aciduria diagnosed in plasma

Background: Primary hyperoxaluria Type 1 (PH1) is a rare autosomal recessive inborn error of glyoxylate metabolism, caused by a deficiency of the liver-specific peroxisomal enzyme alanine:glyoxylate aminotransferase. The disorder results in overproduction and excessive urinary excretion of oxalate, causing recurrent urolithiasis and nephrocalcinosis. Patient and methods: The patient, a 38 year-old-woman, was referred to our lab with severe arthritis in the hips and knees, calcinosis and stage V chronic renal failure under hemodialysis. No urine samples were available to perform organic acids analysis so we studied patient plasma. Samples were extracted with ethylacetate and analyzed by GC-MS. Results: Plasmatic organic acids profile in two different samples revealed a marked excretion of oxalate (131 and 125 µmol/L; controls: 0-5) and glycolate (362 and 338 µmol/L; controls: 9-42). Glicerate concentration was normal (17 and 15 µmol/L; controls: 0-24). Conclusions: The usual biochemical indicator of PH1 is a persistently and markedly elevated urine oxalate. In the absence of urine samples, this biochemical diagnosis can also be done in plasma samples. PH1 is a treatable organic aciduria and an early and accurate diagnosis preserves renal function. So, it is important to screen for PH1 in patients with recurrent urolithiasis or unexplained renal insufficiency.Abstract publicado em: J Inherit Metab Dis. 2013;36(Suppl 2):S178. (P-243).