Hyperoxaluria is the term for high levels of oxalate in the urine. It is normal to pass oxalate in the urine but these levels are lower than 40mg (milligrams) per day. In hyperoxaluria the urinary oxalate levels exceed 40mg within a 24 hour period. The oxalate is produced within the body and/or sourced from certain foods. High levels of oxalate greatly increases the risk of urinary stones. It can also progress to oxalosis where the blood levels of oxalate is raised and oxalate is deposited in various tissues throughout the body.