Primary hyperoxaluria

Primary hyperoxaluria, also referred as primary oxalosis, is a congenital autosomal recessive disease related to a liver enzyme deficiency leading to massive cortical nephrocalcinosis and renal failure.

Please, refer on secondary oxalosis for a discussion on the acquired form of hyperoxaluria.

Epidemiology

Hyperoxaluria is an autosomal recessive disorder and is more common in the Mediterranean countries. The most common subtype is primary hyperoxaluria type 1 which is responsible for approximately 80% of the cases.

Clinical presentation

Typical presentation is nephrolithiasis and global (cortical and medullary) nephrocalcinosis at an early age.

Pathology

It has three types due to the defects in the gene that encodes following enzymes:

• glyoxylate aminotransferase
• glyoxylate reductase/hydroxypyruvate reductase
• liver-specific mitochondrial 4-hydroxy-2-oxoglutarate aldolase enzyme

Radiographic features

Plain radiograph

Plain radiographs demonstrate osteosclerosis as well as osteopenia. Other skeletal abnormalities include fine transverse lines of increased bone density located in areas of rapid growth, submarginal metaphyseal lucency, wide translucent metaphyseal zone with sclerosis of the adjacent diaphysis, and metaphyseal “waisting” or focal narrowing.

Diagnosis by usually by bone (iliac crest) biopsy.

Treatment and prognosis

Treatment is with a combined liver and renal transplantation (the liver is to rectify the enzyme deficiency, not because of liver failure).

The pyridoxine supplementation may be used in conjunction with combined liver-kidney transplantation to enhance the alternative pathway of glyoxylate metabolism to glycine and, therefore, reduce the amount of glyoxylate available for conversion to oxalate.