Laboratory and Molecular Diagnosis of Primary Hyperoxaluria and Oxalosis
Primary hyperoxaluria is a rare, inherited disorder characterized by marked increase in urine oxalate excretion. This excess oxalate combines with calcium to form calcium oxalate, a hard compound that is the main component of kidney stones. Deposits of calcium oxalate can lead to kidney damage, kidney failure, and injury to other organs. Primary hyperoxaluria is caused by the shortage (deficiency) of an enzyme that normally prevents the buildup of oxalate. There are 2 types of primary hyperoxaluria, distinguished by the enzyme that is deficient: primary hyperoxaluria type I (PHI) and primary hyperoxaluria type II (PHII).
Symptoms due to hyperoxaluria may appear anytime from birth to adulthood and presentation can vary from mild to severe. The first sign or symptom is usually blood in the urine, pain, passage of a stone, or urinary tract infection related to a kidney stone. Early diagnosis is of vital importance as primary hyperoxaluria can cause kidney failure, and also can cause severe systemic disease (oxalosis) and death if not adequately treated.
Urine and plasma testing for oxalate, glycolate, and glycerate levels are the main laboratory tests. Several additional tests such as mutation testing for diagnosis, liver biopsy, pyridoxine (vitamin b6) response testing, kidney and bone marrow biopsy can also be useful to diagnose primary hyperoxaluria.