Hyperoxaluria and Oxalosis

What is Hyperoxaluria and Oxalosis?

Hyperoxaluria is a condition where too much of a substance called oxalate is present in the urine. Increased oxalate in the urine can come from eating too much oxalate in foods, or from over-absorption of oxalate by the intestines due to certain diseases (called enteric hyperoxaluria). Hyperoxaluria is uncommon. 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. In its many forms, it may be found among all ages, from infants to people in their 70s.

The highest amounts of oxalate in the urine are seen in diseases in which the liver produces too much oxalate. This occurs in primary hyperoxaluria.

Type I and Type II

Primary hyperoxaluria (PH) is a rare genetic, or inherited, disorder that is present at birth. In a person with Type 1 primary hyperoxaluria, the liver creates too little of an enzyme called alanine:glyoxylate aminotransferase, or AGT. In Type II, the liver is missing a different enzyme, called glyoxylate reductase (GR) or hydroxpyruvate reductase. Very large amounts of oxalate are produced when there is not enough enzyme in the liver.

Over time, oxalate in the urine can cause kidney stones. When very large amounts of oxalate are present in the urine, such as in primary hyperoxaluria, the kidneys can be damaged to the point that they quit working (renal failure).

Oxalosis happens after the kidneys fail and the excess oxalate builds up in the blood, and then spreads to the eyes, bones, muscles, blood vessels, heart and other major organs.

Milder forms of hyperoxaluria can cause kidney stones. Severe hyperoxaluria also causes kidney stones and, if left untreated, can lead to serious illness and even death. Among patients with primary hyperoxaluria, about 50 percent will have kidney failure by age 15, and about 80 percent will have kidney failure by age 30. For that reason, it is critical that primary hyperoxaluria be diagnosed and treated as early as possible.

Patients most often develop the first symptoms, typically kidney stones, anywhere from birth to the mid-20s. But hyperoxaluria may go unrecognized until age 30 to 40. In some patients the first symptom is kidney failure.