primary hyperoxaluria type 2
What is Primary Hyperoxaluria Type 2?
Primary hyperoxaluria type 2 (PH2) is an inherited disease in which the lack of a particular liver enzyme causes the body to accumulate excess amounts of a substance called oxalate. This oxalate leads to a buildup of insoluble calcium salts in the kidneys and other organs. If untreated, it can result in life-threatening kidney failure.
People with PH2 are prone to recurrent kidney stones that can lead to kidney failure. The disease has similar symptoms to primary hyperoxaluria type 1 (PH1), but PH2 tends to be a less aggressive form of the disease, even when symptoms start early in life. PH1 and PH2 are caused by different missing liver enzymes.
In addition to the kidneys, PH2 also leaves insoluble calcium deposits in other body tissues, causing problems with bones, eyes, teeth, nerves, and the heart.
Symptoms typically begin between the ages of 1 and 25, with roughly 80% showing signs of the disease in late childhood or early adolescence. Another 10% of people with PH2 show symptoms in early infancy (before the age of 6 months) while the final 10% do not show symptoms until their 40s or 50s.
How common is Primary Hyperoxaluria Type 2?
PH2 is very rare, though its exact incidence is unknown. As of 2002, only 37 individuals with the disease have been described in medical literature.
How is Primary Hyperoxaluria Type 2 treated?
People with the condition should drink plenty of water. A physician may prescribe medications or other vitamins to help lower oxalate levels and inhibit the formation of kidney stones.
While people with PH2 are less likely to develop kidney failure than people with PH1, organ transplantation remains an option if kidney failure does occur. Because a deficient liver enzyme leads to kidney failure, early liver transplantation may avoid the need to also transplant new kidneys. Kidney replacement alone is not a sufficient treatment as the liver could destroy the new kidneys as well.
People with PH2 should avoid extremely large doses of vitamin C as well as foods high in oxalate, including chocolate, rhubarb, and starfruit.
What is the prognosis for a person with Primary Hyperoxaluria Type 2?
The prognosis for a person with PH2 is variable and depends on how early the disease is detected and treated. Some people with the disease will develop kidney failure that may require liver and kidney transplantation. In other cases, hydration and medication will be sufficient to control the disease.
Generally, people with PH2 have a better long-term outcome than people with PH1 and they require fewer surgeries.
Following organ transplant, some people have lived normal or near-normal lifespans.