hyperoxaluria

Last edited 04/2023 and last reviewed 05/2023

Hyperoxaluria is a uncommon cause of urolithiasis.

Classification:

  • hereditary / primary oxaluria
    • autosomal recessive
    • either inherited enzyme defect (types I and II) or intestinal hyperabsorption (type III)
  • secondary hyperoxaluria
    • vegetarian diet rich in oxalates
    • terminal ileal disease/resecntion with increased oxalate absorption
    • pyrdoxine deficiency or Aspergillus infection

Possible clinical features include:

  • nephrocalcinosis
  • oxalate stones
  • renal failure
  • cardiac manifestations - cardiomyopathy, cardiac conduction defects
  • neurological manifestations - mononeuritis multiplex, peripheral neuropathy
  • osteodystrophy, subcutaneous calcinosis
  • synovitis
  • retinal changes

Treatment options include:

  • dietrary restriction of oxalate (oxalate found in chocolate, tea, beans, nuts, strawberries, rhubarb, beetroot, celary)
  • ensure good fluid intake
  • pyridoxine - reduces urinary oxalate excretion
  • organophosphates - reduces crystal formation
  • NICE have recommended that (1)
    • lumasiran is recommended, within its marketing authorisation, as an option for treating primary hyperoxaluria type 1 (PH1) in people of all ages
    • lumasiran is a subcutaneously administered drug based on the mechanism of RNA interference (2)
      • is a synthetic double-stranded siRNA conjugated with the carbohydrate N-acetylgalactosamine (GalNAc) that targets the hydroxyacid oxidase 1 (HAO1) gene in hepatocytes
        • prevents HAO1 mRNA translation to the enzyme glycolate oxidase (GO).
        • GO catalyzes the conversion of glycolate to glyoxylate, which is the direct precursor of oxalate
        • reduction in GO expression results in a reduction of oxalate production and an increase in glycolate levels
  • transplantation in some cases - hepatic and/or renal

The precipitation of calcium oxalate stones does not seem to depend on urinary pH (in contrast to calcium phosphate stones - precipitated more favourably in alkaline urine).

Reference:

Related pages:

urolithiasis