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Table 2 Summary of diagnostic tests for APRT deficiency and primary hyperoxaluria in the context of dialysis or kidney transplantation. (APRT: Adenine phosphoribosil transferase, AGT: alanine-glyoxylate aminotransferase, DHA: 2,8 dihydroxyadenine, FTIR: Fourier transform infrared microscopy, CKD: chronic kidney disease, ESRD: end stage renal disease). In bold *: test sufficient for diagnosis if positive

From: Recurrence of crystalline nephropathy after kidney transplantation in APRT deficiency and primary hyperoxaluria

  APRT deficiency Primary hyperoxaluria type 1 Advantages Limitations
Kidney stone analysis DHA* nearly 100 % whewellite any stone previously passed can be studied stone required
DHA pathognomonic of APRT deficiency
morphology and composition (100 % whewellite) suggestive of primary hyperoxaluria
Crystalluria DHA* calcium oxalate (whewellite) DHA pathognomonic of APRT deficiency not feasible in anuric patients
whewellite crystalluria may suggest primary hyperoxaluria (unspecific) rare false negative in ESRD patients
FTIR/kidney biopsy DHA* calcium oxalate (whewellite) characterization of crystals in kidney biopsy kdney biopsy required
highly sensitive and specific limited availability
Urinary oxalate   >0.7 mmol/1.73 m2/day suggests primary hyperoxaluria availability, easy to perform no clear cut-off
may be normal in patients with advanced CKD
Plasma oxalate   >30 to 50 μmol/l suggests primary hyperoxaluria availability, easy to perform no clear cut-off
useless in patients without advanced CKD
Enzyme activity decreased APRT activity in erythrocyte lysates* decreased AGT activity in hepatocytes* highly sensitive and specific AGT activity: liver biopsy required, superseded by genetic testing
APRT activity: not reliable after blood transfusion, limited availability
Molecular study mutations in APRT gene (two alleles)* mutations in AGXT gene (two alleles)* identification of 90 % of mutations in APRT gene, >95 % in AGXT gene cost, whole gene sequencing may be required