Primary Hyperoxaluria Type I

Primary Hyperoxaluria Type I

Primary Hyperoxaluria Type I (PH1) is a rare autosomal recessive metabolic disorder that causes high levels of oxalate in the urine and leads to premature kidney failure. It is caused by a defect in the gene AGXT, which provides instructions for making an enzyme called alanine-glyoxylate aminotransferase. This enzyme is responsible for breaking down fructose and glycine, two molecules produced during the digestive process.

People with PH1 develop excessive amount of oxalates in their urine, leading to the crystallization of calcium oxalate. This buildup of oxalate in the kidneys can cause severe damage, leading to kidney failure. Other effects can include gastrointestinal symptoms, pain in the abdomen, and nerve damage.

PH1 is treated with a combination of dietary modifications, medications, and surgery. Treatment focuses on reducing the amount of oxalate that is produced and increasing the elimination of oxalates from the body. Dietary modifications may include limiting high-oxalate foods, increasing dietary calcium, and taking vitamin B6.

Medications that are used to help reduce elevated oxalate levels include allopurinol, citrate supplements, and sodium 2-mercaptoethane sulfonate. These drugs help reduce the amount of oxalate that enters the body and increase its elimination.

Surgery may be necessary to prevent further damage to the kidneys. Surgical treatments may include lithotripsy, which uses shock waves to break up kidney stones; placement of a stent, which will help both urine drainage and reduce stone recurrence; and renal transplantation.

Risk Factors for PH1

  • Family history of PH1
  • Inheritance of two copies of the mutated AGXT gene
  • Age at diagnosis is usually before 5 years of age
  • Incidence of PH1 is higher in individuals of Mediterranean or North African descent

Complications of PH1

  • Kidney failure
  • Urinary stones
  • Nerve damage
  • Gastrointestinal symptoms
  • Liver and pancreatic damage
  • Cardiovascular disease
  • Osteoporosis