|
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AGT activity: liver biopsy required, superseded by genetic testing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
|
