A boy has been referred from primary care. He has been complaining of abdominal pain, in addition to nausea and vomiting. Ultrasound and computed tomography (CT) scans reveal evidence of kidney stones and nephrocalcinosis.
Hypothetical patient representative of typical presentations.
Urine testing is an important factor in achieving a PH1 diagnosis and the diagnosis pathway should include a 24-hour urine analysis1,5. This is the most informative test in the metabolic evaluation of kidney stone diseases, and urinary oxalate is the key marker when investigating hyperoxaluria5. Daily urinary oxalate excretion above the upper limit of normal of ≥45 mg/24 hours (0.5 mmol/1.73 m2) is a biochemical indicator of PH11,5. A spot urine test is based on oxalate:creatinine ratios and may be imprecise; however, this method may be necessary for infants5,6.
Genetic testing is required to confirm a PH1 diagnosis5.
The diagnosis of PH1 is confirmed by the identification of mutations in the AGXT gene through genetic testing using a blood sample4,5. A multigene panel, including AGXT, GRHPR and HOGA1, is recommended to also allow for the potential identification of primary hyperoxaluria type 2 and type 34. In the majority of patients diagnosed with PH1, genetic testing was essential in reaching the diagnosis7.
See the PH1 management section for management options in PH1, and visit OXALEurope.org for guidance on how to measure oxalate and perform genetic testing.
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Date of preparation: March 2021 │ OXL-CEMEA-00010
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