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Primary hyperoxaluria
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Primary hyperoxaluria

Primary hyperoxaluria is a rare genetic condition characterized by the overproduction of oxalate, leading to recurrent kidney stones and potential kidney failure.

Overview

Primary hyperoxaluria results from the overproduction of a substance called oxalate. This leads to abnormally high levels of oxalate in the urine (hyperoxaluria). Oxalate can combine with calcium to form calcium oxalate, which creates hard deposits in the kidneys and bladder. Over time, these deposits can damage the kidneys, leading to end-stage renal disease (ESRD).

Symptoms

  • Recurrent kidney and bladder stones.
  • Blood in the urine (hematuria).
  • Urinary tract infections.
  • Kidney damage and potential end-stage renal disease (ESRD).
  • Systemic oxalosis: As kidney function declines, oxalate levels in the blood rise and deposit in tissues throughout the body, particularly in bones and blood vessel walls.
  • Bone fractures (due to oxalosis in the bones).

Types and Causes

There are three types of primary hyperoxaluria, each caused by mutations in specific genes that provide instructions for enzymes involved in breaking down protein building blocks and other compounds:

  • Type 1: Caused by mutations in the AGXT gene. Kidney stones typically appear from childhood to early adulthood.
  • Type 2: Caused by mutations in the GRHPR gene. Similar to type 1, but ESRD typically develops later in life.
  • Type 3: Caused by mutations in the HOGA1 gene. Affected individuals often develop kidney stones in early childhood.

Inheritance

This condition is inherited in an autosomal recessive pattern, meaning both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene but typically do not show signs or symptoms of the condition.

Frequently Asked Questions

The key steps are measuring urinary oxalate excretion (often >0.5 mmol/24 h) and performing genetic testing for AGXT, GRHPR, or HOGA1 mutations. A family history of early‑onset stones and lack of dietary or gastrointestinal risk factors also point toward the primary form.
High‑dose pyridoxine (vitamin B6) can enhance residual AGXT enzyme activity in about 30‑50 % of type 1 patients, reducing urinary oxalate. In addition, aggressive hydration (≥2–3 L/m²/day), citrate supplementation, and, in selected cases, RNA‑interference therapies (e.g., lumasiran) are used to suppress hepatic oxalate synthesis.
Dialysis is initiated when estimated glomerular filtration rate falls below ~15 mL/min/1.73 m² or when systemic oxalosis threatens other organs. Definitive treatment for type 1 is a combined liver‑kidney transplant, because the liver provides the missing enzyme. Isolated kidney transplant without liver replacement often fails due to recurrent oxalate deposition.
Patients should limit high‑oxalate foods (spinach, rhubarb, nuts, tea) while maintaining adequate calcium intake (500–1000 mg/day) to bind intestinal oxalate. Vitamin C should be kept below 200 mg/day because it can be metabolized to oxalate. A low‑salt, normal‑protein diet supports kidney health, and a registered dietitian experienced in metabolic kidney disease should tailor the plan.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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