Primary Hyperoxaluria (PH)

Primary hyperoxaluria (PH) is a rare inherited metabolic disorder that is identified by the overproduction of oxalate, a naturally occurring chemical in the body.

After oxalate is produced in the liver, it leaves the body in urine. However, if there are high oxalate levels, the extra oxalate often forms kidney stones or directly damages the kidney tissue. High levels of oxalate in the body can also damage other organs in the body like the bones, skin, heart, and eyes.

Over time, your child may experience a loss of kidney function and even kidney failure. If this happens, they will require dialysis or a kidney transplant.

There are three types of PH: PH1, PH2, and PH3. They are characterized by different genetic mutations and metabolic changes. Genetic testing and urine tests can help identify your child’s specific diagnosis.

Children with PH are often diagnosed because they develop multiple kidney stones and have loss of kidney function. Sometimes evaluations for frequent urinary tract infections (UTI), blood in the urine, or flank (side) or back pain will lead to a diagnosis. PH might be diagnosed if your child has:

• Kidney stones forming early in childhood
• Recurrent kidney stones
• Nephrocalcinosis (calcium deposits in the kidney tissue)
• Reduced kidney function or kidney failure with unclear cause
• A family history of kidney problems or kidney stones
• A family history of PH

However, it is important to note that PH1 is the most common form of PH. To prevent kidney stones and the risk of kidney damage to your child, it’s important to diagnose PH as soon as possible so that effective therapies can be started.

At Boston Children’s Hospital, we treat PH with a multidisciplinary approach. Your child’s care team may include:

• Nephrologists, who manage the medical therapies for PH
• Urologists, who help manage the surgical treatments
• Dietitians, who help with any dietary changes that your child’s nephrologist may recommend

Initial PH treatment includes very high daily fluid intake and medications, like potassium citrate, that can help calcium oxalate crystals dissolve in the body. Treatment with pyridoxine (vitamin B6) or RNA interference drugs may lower urine oxalate and blood oxalate levels in PH1. Children with PH who develop kidney failure may require dialysis or transplantation.

Research can help us better understand how to treat all forms of PH. Our team frequently participates in clinical trials to help further our knowledge of PH and its treatment.

Boston Children’s is the first pediatric center designated as a Center of Excellence through the Oxalosis and Hyperoxaluria Foundation’s (OHF) Care Center Network.

As a PH Center of Excellence, we are constantly working to broaden awareness of PH, to advance research into new PH therapies, and to improve the outcomes of children with PH under our care.