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Primary hyperoxaluria (PH): A group of rare genetic diseases caused by excessive overproduction of oxalate, which is toxic to the kidneys

PH is a family of rare inherited disorders of the liver that can cause damage throughout the body, beginning with the kidneys. In many people, kidney stones may be the first sign of PH.

How PH is inherited

Oxalate overproduction in the liver


When people are born with a genetic mutation for PH, they lack certain liver enzymes. This lack of enzymes results in an overproduction of a waste product called oxalate, which is damaging to the body’s organs. Our bodies send that waste to the kidneys, which eliminate it in the urine.

Illustration of oxalate overproduction in the liver

Crystal formation and stones in the kidneys


As oxalate builds up in the kidneys, it combines with calcium to form calcium oxalate crystals.


These crystals can clump together to form kidney stones. Calcium oxalate crystals can also deposit into the kidney tissue, causing calcium to build up, a condition known as nephrocalcinosis.

Illustration of crystal formation and stones in the kidneys

Chronic kidney disease


Over time, the buildup of calcium oxalate crystals in the kidneys can cause damage, making it hard for them to do their job—which is to filter out waste. This condition is called chronic kidney disease (CKD). The speed at which CKD progresses is different from person to person. Some people with PH develop CKD quickly, while others may develop CKD over a long period of time—or they may not develop CKD at all.

Illustration of chronic kidney disease

Later stages of CKD


In some people with PH, calcium oxalate crystals can build up so much that their kidneys eventually reach an advanced stage of CKD. People in the later stages of CKD may need frequent dialysis, a kidney transplant, or both a kidney and a liver transplant.

Illustration of later stages of chronic kidney disease

Sometimes PH can affect organs beyond the kidneys


As the kidneys become more damaged by calcium oxalate crystals and/or kidney stones, they will start to lose the ability to filter out wastes and harmful substances, including oxalate. At this stage of kidney damage, a healthcare provider may start frequent dialysis. This may help prevent a condition called systemic oxalosis, which happens when oxalate begins to circulate throughout the body and build up in other organs, including the heart, bones, retina, and skin.


Signs of systemic oxalosis include bone pain, anemia, fractures, heart problems, vision loss, open sores (called ulcers), and bumps (called nodules).

Female skeleton with calcium oxalate crystals highlighted
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"It is not just a kidney stone that my children or any patient suffers through, but an emotional, often debilitating disease.”

– Mother of two children with PH2

No kidney stones?

Remember, even if you don’t have kidney stones, calcium oxalate crystals can still be building up in your kidneys and possibly other parts of your body, causing damage. It’s important to talk to your healthcare provider about monitoring your oxalate levels.

Female skeleton with oxalate crystals throughout body
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