[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Conditions](https://durgical.com/en/conditions/) › Primary hyperoxaluria [Conditions](https://durgical.com/en/conditions/) · [Metabolism (biochemistry)](https://durgical.com/en/conditions/) # Primary hyperoxaluria A liver enzyme defect makes the body produce too much oxalate, which forms calcium oxalate stones and can destroy the kidneys from childhood. Updated 2026-11-01 ## Structures involved Tap one to see what it is and open it in 3D. - [Kidneys](https://durgical.com/en/anatomy/kidney/) - [Renal pelvis](https://durgical.com/en/anatomy/renal-pelvis/) - [Ureters](https://durgical.com/en/anatomy/ureter/) - [Urinary bladder](https://durgical.com/en/anatomy/urinary-bladder/) - [Liver](https://durgical.com/en/anatomy/liver/) ## In biochemistry - [Protein targeting and signal sequences](https://durgical.com/en/biochemistry/topics/protein-targeting-and-signal-sequences/) ## What it is A group of inherited disorders of glyoxylate metabolism in the liver that cause oxalate overproduction, kidney stones, nephrocalcinosis and kidney failure. ## Who gets it About 1 in 58,000 people worldwide; type 1 is about 80 % of cases and types 2 and 3 about 10 % each. More frequent where consanguinity is common. No Colombian figures are published. ## Causes - Type 1: variants in AGXT (peroxisomal alanine–glyoxylate aminotransferase, a vitamin B6 enzyme) - Type 2: variants in GRHPR (glyoxylate/hydroxypyruvate reductase) - Type 3: variants in HOGA1 (mitochondrial 4-hydroxy-2-oxoglutarate aldolase) - All are autosomal recessive ## Risk factors - Carrier parents; consanguinity - Dehydration, which raises urinary oxalate concentration ## Pathophysiology Normally liver AGT turns glyoxylate into glycine inside peroxisomes. When AGT is missing (or mistargeted to mitochondria by some variants), glyoxylate is oxidised by lactate dehydrogenase to oxalate, and glycolate also rises. Oxalate cannot be metabolised by humans and is excreted by the kidneys, where it binds calcium and forms crystals, stones and nephrocalcinosis. As GFR falls, plasma oxalate rises and calcium oxalate deposits in bone, heart, vessels, [retina](https://durgical.com/en/anatomy/retina/) and [skin](https://durgical.com/en/anatomy/skin/) (systemic oxalosis). ## Classification - Type 1 (AGXT): most common and most severe; urinary glycolate high; some respond to pyridoxine - Type 2 (GRHPR): urinary L-glycerate high; usually milder - Type 3 (HOGA1): stones in childhood, kidney failure uncommon ## Symptoms and signs - Recurrent kidney stones from childhood - Blood in urine and renal colic - Urinary infections - In infants: failure to thrive and early kidney failure ## Red flags - Kidney stones in a child - Nephrocalcinosis with falling kidney function - Recurrent calcium oxalate stones after a kidney transplant ## Diagnosis **Clinical** Recurrent or early calcium oxalate stones, nephrocalcinosis or unexplained [kidney](https://durgical.com/en/anatomy/kidney/) failure, often with a family history. **Tests** 24-hour urine oxalate (high), urinary glycolate and L-glycerate, stone analysis (calcium oxalate monohydrate), plasma oxalate in kidney failure, kidney function. Genetic testing of AGXT, GRHPR and HOGA1 confirms the type. **Imaging** Kidney ultrasound or CT showing stones and nephrocalcinosis; bone and heart imaging in systemic oxalosis. ## Treatment **Lifestyle** Very high fluid intake spread through the day and night to dilute urine **Medical** Citrate to inhibit calcium oxalate crystallisation, and pyridoxine (vitamin B6) in responsive type 1 **Medical** RNA interference medicines that reduce hepatic oxalate production (lumasiran, nedosiran) in type 1, under specialist care **Procedure** Removal of obstructing stones by urological procedures; intensive dialysis when kidneys fail **Surgical** Combined [liver](https://durgical.com/en/anatomy/liver/) –kidney transplant (or sequential) in type 1 with kidney failure, because kidney transplant alone recurs **Follow-up** Monitoring of kidney function, urine oxalate and systemic deposits ## Complications - Chronic kidney disease and end-stage kidney failure - Systemic oxalosis: bone pain and fractures, heart conduction defects, retinopathy, skin ulcers - Recurrence in a transplanted kidney ## Prognosis Type 1 often leads to kidney failure by early adulthood without treatment; new liver-directed therapies are improving the outlook. ## Test yourself Think of the answer, then tap the question to see it. ## Which enzyme is deficient in primary hyperoxaluria type 1 and where is it located? Alanine–glyoxylate aminotransferase (AGT, gene AGXT), a vitamin B6 enzyme of liver peroxisomes. ## Why does glyoxylate turn into oxalate when AGT is missing? Unconverted glyoxylate is oxidised by lactate dehydrogenase to oxalate, which humans cannot break down. ## Which vitamin helps some patients with type 1? Pyridoxine (vitamin B6), the precursor of the AGT cofactor pyridoxal phosphate. ## Why is kidney transplant alone not enough in type 1? The liver keeps overproducing oxalate, which damages the new kidney; the liver must also be treated or replaced. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/conditions/primary-hyperoxaluria/) ## Related conditions - [Kidney stones (urolithiasis)](https://durgical.com/en/conditions/kidney-stones/) - [Chronic kidney disease](https://durgical.com/en/conditions/chronic-kidney-disease/) - [Ethylene glycol poisoning](https://durgical.com/en/conditions/ethylene-glycol-poisoning/) Educational information, not medical advice. For any symptom, see a health professional. Sources: [Primary hyperoxaluria: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/primary-hyperoxaluria/) (MedlinePlus, US National Library of Medicine, 2026); [AGXT gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/agxt/) (MedlinePlus, US National Library of Medicine, 2026); [GRHPR gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/grhpr/) (MedlinePlus, US National Library of Medicine, 2026); [HOGA1 gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/hoga1/) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011). [← All conditions](https://durgical.com/en/conditions/) ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. 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