Overview of Hyperoxaluria
Kidney stones are on the rise. One cause is a condition called hyperoxaluria — when you have too much oxalate in your urine. Oxalate is a natural chemical in your body, and it’s also found in certain types of food. There is no known need for oxalate by the human body, it is normally eliminated as waste through the kidneys. But too much oxalate in your urine can cause serious problems when the excess oxalate binds with calcium in the urine to form kidney stones.
Hyperoxaluria can be caused by eating too many oxalate-rich foods, an intestinal disease or an inherited (genetic) disorder. In some persons the cause of the disease is not known, but may result from changes in the way kidneys handle normal amounts of body oxalate. Hyperoxaluria is uncommon, though can be found in about 20 percent of individuals with kidney stones. Quick diagnosis and treatment of hyperoxaluria is important to the long-term health of your kidneys.
Primary hyperoxaluria (PH). Is a rare, inherited (genetic) disorder of liver metabolism that often results in life-threatening damage to the kidneys. In this type, the liver doesn’t create enough of a certain protein (enzyme) that prevents overproduction of oxalate, or the enzyme doesn’t work properly. Unlike dietary or enteric hyperoxaluria, the amount of oxalate in the urine is not greatly affected by changes in dietary oxalate.
Secondary hyperoxaluria. Caused by excess absorption of oxalate from the gastrointestinal tract due to underlying gastrointestinal conditions such as gastric bypass, Crohn’s Disease, short bowel syndrome or other malabsorption disorders causing enteric hyperoxaluria. Avoiding, foods high in oxalate in particularly important. Learn more…
Types of PH
PH is a rare, occuring in one to three people out of a million. It may be found among all ages, from infants to late adulthood. Three types of PH are currently known and can be readily diagnosed. Each of the types of PH causes a decrease in activity of a specific enzyme in the liver which causes an increase in oxalate production. The decrease in the enzyme activity in each case changes how the liver makes oxalate, and a much larger amount of oxalate is produced.
The enzymes involved in the three disorders are as follows:
- PH1: alanine-glyoxylate aminotransferase, or AGT
- PH2: glyoxylate/hydroxypyruvate reductase, or GR/HPR
- PH3: 4-hydroxy-2-oxoglutarate aldolase, or HOGA
Very large amounts of oxalate are produced when there is not enough of these enzymes in the liver. Excess oxalate is eliminated through your kidneys, in your urine. The extra oxalate can combine with calcium to create kidney stones and crystals, which can damage the kidneys and cause them to stop working (renal failure).
It is possible that other types of PH will be discovered. Some patients have high urine oxalates and kidney stones but do not have a genetic mutation that causes one of the three known types of PH. Future research may help us to better understand the cause of the high urine oxalate in these patients.
Oxalosis is a rare metabolic disorder that occurs when the kidneys stop eliminating calcium oxalate crystals from the body through the urine. Because the kidneys stop working, oxalate crystals are deposited elsewhere in the body. Oxalosis in its late stages can cause a variety of complications outside the kidney, including bone disease, anemia, skin ulcers, heart and eye problems, and in children, a failure to develop and grow normally.