Hyperoxaluria is a condition that occurs when there is an excess amount of oxalate in the urine. Oxalate is a natural substance that is normally in the body and is also found in various foods, but having too much oxalate can be dangerous. Oxalate combines with calcium to form calcium oxalate, which makes kidney stones. The calcium oxalate can build up and cause kidney damage, kidney failure, and damage to other parts of the body. There are two main types of hyperoxaluria: primary and secondary. Primary hyperoxaluria is a genetic condition. There are two types of primary hyperoxaluria. Type 1 is caused by changes (mutations) in the AGXT gene and type two is caused by mutations in the GRHPR gene. Secondary hyperoxaluria occurs when a person gets too much oxalate from the foods that they eat. Foods that contain oxalate include berries, kiwis, figs, purple grapes, rhubarb, okra, leeks, spinach and chocolate.
If a person has symptoms of hyperoxaluria, such as kidney stones or kidney failure, the doctor will usually start by performing a physical exam. Additional tests are usually needed to find the issue. These may include getting images of the kidney (such as an x-ray or CT scan) or collecting a small piece of the kidney (kidney biopsy) as well as blood and urine tests. A high level of oxalate in the urine strongly suggests a diagnosis of hyperoxaluria. Genetic testing is needed to confirm a diagnosis of primary hyperoxaluria. Early diagnosis and treatment is very important in order to prevent severe problems, such as kidney failure. Treatment options depend on the type of hyperoxaluria a person has. Avoiding foods that are high in oxalate is usually recommended. A kidney transplant or dialysis may be needed to treat kidney failure. If your child has been diagnosed with hyperoxaluria, talk with their doctor to discuss current treatment recommendations. Support groups are good resources for support and additional information.