Infant with failure to thrive

Infant presentation

A female infant presenting with a fever with possible urinary tract infection and a failure to thrive. She has been referred from primary care.

Hypothetical patient representative of typical presentations.

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Diagnosis

Urine testing

Urine testing is an important factor in achieving a PH1 diagnosis and the diagnosis pathway should include a 24-hour urine analysis^1,5. 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 PH1^1,5. A spot urine test is based on oxalate:creatinine ratios and may be imprecise; however, this method may be necessary for infants^5,6.

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 sample^4,5. 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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Management options