Primary Hyperoxaluria Type 1 (PH1)

What is primary hyperoxaluria type 1 (PH1)?

Primary hyperoxaluria type 1 (PH1) is a rare disorder that affects the kidneys. PH1 results from buildup of oxalate, which normally is filtered through the kidneys and excreted in the urine. For those with PH1, the oxalate accumulates in the kidneys and urinary tract and combines with calcium to form the main component of kidney and bladder stones (calcium oxalate).

What are the symptoms of primary hyperoxaluria type 1 (PH1)?

• Kidney and bladder stones (and symptoms associated with kidney/bladder stones)
• Stunted growth
• Kidney damage
• Renal failure

What causes primary hyperoxaluria type 1 (PH1)?

PH1 is caused by mutations in a gene called AGXT, which instructs the body to make the enzyme alanine-glyoxylate aminotransferase.  Mutations in the AGXT gene prevent the breakdown of glyoxylate, causing an accumulation that leads to oxalate. Excess oxalate that is not excreted combines with calcium to form calcium oxalate, which damages the kidneys and other organs.

How is primary hyperoxaluria type 1 (PH1) diagnosed?

PH1 is often diagnosed after clinical evaluation, detailed patient history, and identification of characteristic symptoms.

A diagnosis may be confirmed through:

• Blood test
• Imaging test
• Molecular genetic testing
• Biopsy

What are the treatments for primary hyperoxaluria type 1 (PH1)?

The goal of PH1 treatment is to minimize calcium oxalate and maintain renal function. Early diagnosis and therapy is critical to preserve the function of the kidneys for as long as possible.

Treatments include:

• Oral potassium citrate
• Drugs such as thiazides or pyridoxine
• Avoiding large intakes of vitamins C and D
• Dietary calcium supplements
• Intake of large amounts of fluids

Dialysis or organ transplantation are possible options if the disease progresses severely.

Where can I find out more about primary hyperoxaluria type 1 (PH1)?

• NIH
• National Organization for Rare Diseases (NORD)
• Orphanet