Diagnosing PH
Many Patients With Primary Hyperoxaluria Experience a Significant Delay From Initial Symptom Onset to Diagnosis1-3
42% of patients with PH experience a significant delay in diagnosis1
Patients experience 3.4 ± 5.4 years between first symptom presentation and diagnosis1
One study reported that 27% of patients are diagnosed at ESRD, with delay of 3.5 years after symptom onset2
A separate study found that ~5% are diagnosed after kidney transplant3
19% diagnosed after transplant are not diagnosed until after first transplant failure3
Diagnosis Typically Begins With 24-Hour Urine Collection and Kidney Stone Analysis4
24-hour urine tests can also uncover other genetic
drivers of stone formation such as cystinuria6
*Urinary oxalate >0.5 mmol/1.73 m2/24 hours and/or plasma oxalate >20 µmol/L.5
Patients with primary hyperoxaluria present with certain characteristics. For both pediatric and adult patients, these characteristics may include a history of kidney stones or nephrocalcinosis (a condition marked by the buildup of calcium deposits in the kidney), a family history of hyperoxaluria (excess oxalic acid or oxalate in the urine), or chronic kidney disease, defined as a glomerular filtration rate (GFR) of <50 mL/min/1.73 m2 or a serum creatinine ≥2 times normal for age.5,7,8
Screening for primary hyperoxaluria should be undertaken in a child with a first kidney stone, in an adult with recurrent kidney stones, and in patients with nephrocalcinosis or a family history of kidney stones.9
24-Hour urine collection
Careful 24-Hour Urine Collection for an Accurate Diagnosis
In patients with otherwise normal renal function, urine should be collected ideally over 24 hours. Persistently elevated oxalate (>0.7 mmol/1.73 m2/day) or a urine oxalate-to-creatinine ratio greater than normal for age may suggest primary hyperoxaluria.5
The 24-hour urine test is important in identifying primary hyperoxaluria, but it places the burden on the patient for compliance and can be especially challenging in the case of infants and children. Patients should be informed about how to adequately collect, store, and time collections.10,11