All you need to know about: hyperoxaluria

Oxalate is a natural substance normally removed by the body through urine, but in some people, it can accumulate and combine with calcium to form crystals that gradually damage the kidneys. This hidden buildup, often mistaken for ordinary kidney stones, can progress without obvious symptoms, affecting overall kidney function. In severe cases, other organs also can be at risk. Early detection, monitoring and timely treatment are crucial to prevent this condition — know as hyperoxaluria.

What is hyperoxaluria?

Hyperoxaluria is a metabolic disorder in which the body produces or absorbs excessive amounts of oxalate. Such metabolic and genetic disorders that disrupt normal waste elimination can lead to progressive organ damage if not detected early. In the case of hyperoxaluria, excess oxalate combines with calcium to form crystals, most commonly calcium oxalate stones, which gradually injure the kidneys.

In primary hyperoxaluria, defects in specific liver enzymes result in continuous overproduction of oxalate from an early age. Studies note that because early symptoms often resemble routine kidney stone disease, it is frequently underdiagnosed, especially in younger patients.

What are the signs and symptoms?

Recurrent kidney stones are often the earliest sign of hyperoxaluria. Patients may experience severe pain in the back or abdomen, blood in the urine and painful or frequent urination. Recurrent urinary tract infections are also commonly reported. In children with inherited forms of this condition. Symptoms may include vomiting, eating difficulties and poor growth.

As oxalate builds up over time, persistent crystal deposits can gradually damage kidney tissue and reduce renal function completely. Research published in Nature Reviews Nephrology highlights that when the kidneys’ ability to clear oxalate declines, the substance can accumulate in the bloodstream and spread to other organs too. This advanced stage, called systemic oxalosis, can affect the bones, eyes, blood vessels and heart, leading to bone pain, fractures, anaemia, visual problems, and cardiovascular complications.

Who is at risk?

Individuals who inherit defective genes from both parents are at the highest risk of developing primary hyperoxaluria. Siblings of affected patients are therefore advised to undergo early evaluation.

People with chronic intestinal conditions are also considered vulnerable. Disorders such as inflammatory bowel disease, fat malabsorption syndromes and prior intestinal or bariatric surgery can significantly increase oxalate absorption from the gut. Dietary patterns high in oxalate-rich foods, particularly when calcium intake is low, may further increase urinary oxalate levels in some individuals. A family history of kidney stones or unexplained kidney disease is regarded as an important clinical warning sign.

What are the treatment options?

According to recommendations published in Nature, management of hyperoxaluria focuses on reducing oxalate levels, preventing stone formation and preserving kidney function. High fluid intake is widely recommended to dilute urine and reduce crystal formation. In a few cases, dietary strategies aimed at limiting oxalate absorption can be beneficial.

Clinical studies also show that vitamin B6 therapy can reduce oxalate production in some patients with specific genetic subtypes of primary hyperoxaluria. In recent years, research has highlighted the role of RNA-interference–based therapies that target oxalate production in the liver, representing a major advance in treatment for certain patients.

When kidney stones cause an obstruction or infection, surgical or endoscopic intervention may be required. In advanced kidney failure, dialysis is used to manage metabolic waste, though studies note that it does not fully eliminate oxalate. According to outcomes reported in international transplant registries and studies, combined liver and kidney transplantation remains the definitive treatment for severe primary hyperoxaluria, as it corrects the underlying metabolic defect while restoring renal function.

Early diagnosis, appropriate genetic counselling and sustained follow-up are essential, as timely intervention can prevent irreversible organ damage and significantly improve outcomes.