Primary hyperoxaluria type 1 in Tunisian children

Primary hyperoxaliuria type 1 is an autosomal recessive disorder characterized by increasing urinary excretion of calcium oxalate, recurrent urolithiasis, nephrocalcinosis, and accumulation of insoluble oxalate throughout the body. This inborn error of metabolism appears to be a common cause of end stage renal disease in Tunisia.

To review the clinical, biological and radiological futures of primary hyperoxaluria type 1 and to correlate these aspects with the development of end-stage renal disease.

we retrospectively reviewed 44 children with Primary hyperoxaliuria type I who were treated in our department during a period of 15 years between 1995 and 2009. The diagnosis was established by quantitative urinary oxalate excretion. In patient with renal impairment, the diagnosis was made by infrared spectroscopy of stone or by renal biopsy.

Male to female ratio was 1.2. The median age at diagnosis was 5.75 years. About 43 % of those were diagnosed before the age of 5 years. Initial symptoms were dominated by uraemia. Four patients were asymptomatic and diagnosed by sibling screening of known patients. Nephrocalcinosis was present in all patients. It is cortical in 34%, medullary in 32% and global in 34%. At diagnosis, twelve children were in end-stage renal disease (27%). Pyridoxine response, which is defined by a reduction in urine oxalate excretion of 60% or more, was found in 27%.

In the majority of patients, the clinical expression of Primary hyperoxaliuria type 1 is characterized by nephrocalcinosis, urolithiasis and renal failure. Pyridoxine sensitivity is associated with better outcome.