Introduction

Primary hyperoxalurias (PH) are very rare diseases characterised by overproduction and accumulation of oxalate in the body. The main target organ is the kidney, as oxalate cannot be metabolised and is excreted in the urine, leading to nephrocalcinosis, recurrent urolithiasis, and subsequent renal impairment. During the last decade, major advances in enzymology, molecular genetics, and cell biology have generated excellent reviews on both pathophysiology and management^1 2; however, specific questions remain unanswered.

	Urinary oxalate

Basically, hyperoxaluria (normal urinary oxalate < 0.5 mmol/1.73 m² per day; normal urinary oxalate to creatinine ratio < 0.10 mmol/mmol) and calcium oxalate crystallisation are the hallmarks of any kind of PH.¹ The presence of monohydrated calcium oxalate crystals in the urine or tissues can be assessed by infrared spectrometry or polarised light microscopy.³ Hyperoxaluria may be associated with increased urinary excretion of either glycolate in PH1 or L-glycerate in PH2, but urinary metabolites are no longer adequate for accurate . . . [Full text of this article]