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Wegowski Disease (Primary Hyperoxaluria)

Overview

Wegowski disease, more formally known as primary hyperoxaluria (PH), is a rare inherited metabolic disorder in which the liver produces too much oxalate. Oxalate combines with calcium to form calcium‑oxalate crystals that deposit in the kidneys and other organs, leading to kidney stones, kidney damage, and systemic complications.

• Type of disorder: Autosomal‑recessive (most forms); a few cases are autosomal‑dominant.
• Who it affects: Both sexes, all ages; symptoms typically appear in childhood but milder forms may not be diagnosed until adulthood.
• Prevalence: Approximately 1–3 per 1 million people worldwide for PH type 1, the most common form. Overall, combined prevalence of all PH types is estimated at 1–2 per 100 000 people.<sup>[1][2]</sup>

Symptoms

Symptoms stem from calcium‑oxalate crystal formation in the urinary tract, kidneys, and, in advanced disease, other organs. The presentation can be highly variable.

Kidney‑related symptoms

• Recurrent kidney stones: Often the first sign; stones are typically calcium‑oxalate, may be radiolucent on X‑ray.
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• Hematuria (blood in urine): Microscopic or gross.
• Flank pain: Due to stone passage or obstruction.
• Urinary urgency or frequency: Especially with bladder crystal deposition.
• Decreased kidney function: Measured by rising serum creatinine or reduced estimated glomerular filtration rate (eGFR).

Systemic symptoms (usually in later stages)

• Bone pain and fractures: Calcium‑oxalate can deposit in bone.
• Skin lesions: Small, whitish papules or nodules (oxalate cutis).
• Eye problems: Conjunctival deposits causing irritation.
• Fatigue, poor growth (children): Result of chronic kidney disease (CKD).
• Gastrointestinal upset: Nausea or vomiting occasionally reported when stones cause obstruction.

Causes and Risk Factors

Primary hyperoxaluria is caused by mutations in genes that encode enzymes involved in glyoxylate metabolism. The three main types are:

1. PH type 1 (AGXT gene): Deficiency of alanine‑glyoxylate aminotransferase (AGT). Accounts for ~70‑80 % of cases.
2. PH type 2 (GRHPR gene): Deficiency of glyoxylate‑reducing hydroxy‑proline reductase (GRHPR).
3. PH type 3 (HOGA1 gene): Deficiency of 4‑hydroxy‑2‑oxoglutarate aldolase (HOGA).

All three are inherited in an autosomal‑recessive pattern, meaning a child must inherit two defective copies (one from each parent) to develop disease. Carriers (one defective copy) are usually asymptomatic.

Risk factors

• Consanguineous marriage (increases chance of inheriting two copies of a pathogenic variant).
• Family history of kidney stones, early‑onset renal failure, or known PH.
• Ethnic groups with reported founder mutations (e.g., certain Mediterranean, French‑Canadian, or Arab populations).
• Underlying metabolic conditions that raise oxalate production (rarely, secondary hyperoxaluria from intestinal malabsorption).

Diagnosis

Because early symptoms mimic common kidney stones, a high index of suspicion is required, especially in children with recurrent stones or a positive family history.

Laboratory tests

• Urine oxalate concentration: Spot urine or 24‑hour collection; values >0.5 mmol/24 h are strongly suggestive.
• Plasma oxalate: Elevated >30 µmol/L in patients with normal renal function; rises markedly as kidney function declines.
• Kidney function panel: Serum creatinine, eGFR, electrolytes.

Imaging

• Ultrasound: Detects renal stones, nephrocalcinosis, and kidney size.
• CT scan (non‑contrast): Gold standard for stone burden.

Genetic testing

Sequencing of AGXT, GRHPR, and HOGA1 genes confirms the diagnosis and determines the PH type. Testing is recommended for the patient and, if a pathogenic variant is found, for siblings and parents.

Kidney biopsy (rare)

May be used when the diagnosis is uncertain; reveals calcium‑oxalate crystals within tubules and interstitium.

Treatment Options

Management aims to reduce oxalate production**, limit stone formation, protect kidney function, and, when necessary, replace kidney function.

Medical therapies

• Pyridoxine (Vitamin B6): Effective in ~30‑50 % of PH type 1 patients with responsive mutations (e.g., Gly170Arg). Doses 5–20 mg/kg/day divided TID. Improves AGT activity, lowering oxalate.<sup>[3]</sup>
• RNAi therapy – Lumasiran: Small interfering RNA that silences glycolate oxidase (GO) in the liver, decreasing oxalate production. FDA‑approved for PH type 1 (2020). Dosing: subcutaneous injection every 3 months after loading phase.
• Calcium‑oxalate binders (e.g., oral calcium citrate): Increases intestinal calcium to bind oxalate and reduce absorption; especially useful when secondary hyperoxaluria from gut malabsorption coexists.
• Potassium citrate: Alkalinizes urine, reducing stone formation.
• Probiotics (Oxalobacter formigenes): Experimental; bacteria degrade intestinal oxalate, modestly lowering urinary excretion.

Dietary & lifestyle measures

• Limit high‑oxalate foods: spinach, beets, nuts, chocolate, tea.
• Maintain adequate hydration: >2–3 L/day (or urine output >2 L/24 h) to dilute oxalate.
• Avoid excessive vitamin C (>1 g/day) because it is metabolized to oxalate.
• Low‑salt diet to reduce calcium excretion.

Surgical / procedural interventions

• Extracorporeal Shock Wave Lithotripsy (ESWL) or ureteroscopy: For stone removal when symptomatic.
• Renal transplantation: Considered when eGFR <20 mL/min/1.73 m² and systemic oxalate burden is controlled.
• Liver‑kidney transplant: The definitive cure for PH type 1, because the defective enzyme is hepatic. Indicated for patients with progressive renal failure despite maximal medical therapy.

Supportive care

• Management of CKD (blood pressure control, avoidance of nephrotoxins).
• Dialysis (hemodialysis or peritoneal) to remove excess oxalate while awaiting transplant; intensive dialysis (6 h daily) may be needed to keep plasma oxalate <30 µmol/L.

Living with Wegowski disease (primary hyperoxaluria)

Patients can lead active lives with careful management.

• Hydration tracking: Use a water bottle with volume markings or a smartphone app.
• Regular monitoring: Quarterly urine oxalate, bi‑annual kidney function labs, annual genetic counseling.
• Medication adherence: Set alarms for pyridoxine or lumasiran injections.
• Dietary planning: Work with a renal dietitian to create low‑oxalate meal plans that still meet protein and calorie needs, especially for children.
• Physical activity: Moderate exercise improves cardiovascular health and aids fluid intake.
• Psychosocial support: Join patient advocacy groups (e.g., the Primary Hyperoxaluria Foundation) for counseling and peer support.

Prevention

Because PH is genetic, primary prevention (preventing disease onset) is not possible for affected individuals. However, the following steps can reduce disease severity and complications:

• Genetic counseling for at‑risk couples; carrier testing can inform reproductive decisions.
• Early screening of siblings when a child is diagnosed – urine oxalate measurement can catch asymptomatic cases.
• Strict adherence to hydration and dietary recommendations from the time of diagnosis.
• Avoidance of vitamin C megadoses and calcium‑oxalate‑rich supplements.

Complications

If left untreated or poorly controlled, PH can lead to serious health problems:

• End‑stage renal disease (ESRD): Occurs in 30‑50 % of PH type 1 patients by the third decade.<sup>[4]</sup>
• Systemic oxalosis: Deposition of oxalate in bone, heart, retina, and skin, causing pain, cardiomyopathy, visual loss, and skin ulceration.
• Recurrent urinary tract infections (UTIs): Due to stones acting as a nidus.
• Hypertension: Secondary to CKD.
• Growth retardation in children: From chronic kidney disease and metabolic burden.

When to Seek Emergency Care

References

1. Jude Nilsson et al., “Primary hyperoxaluria: a review of the genetics and clinical management,” Kidney International, 2022.
2. Centers for Disease Control and Prevention. “Rare Disease Information: Primary Hyperoxaluria.” Updated 2023.
3. Gupta P, et al., “Pyridoxine responsiveness in primary hyperoxaluria type 1,” Clinical Kidney Journal, 2021.
4. Mayo Clinic. “Primary hyperoxaluria – outcomes.” Accessed June 2024.
5. U.S. Food & Drug Administration. “Lumasiran (OXLUMO) Prescribing Information.” 2020.

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