Immunoglobulin A Nephropathy (IgA Nephropathy) – A Complete Patient Guide

Overview

Immunoglobulin A nephropathy (IgA nephropathy), also called Berger disease, is a chronic kidney disorder characterized by the buildup of the antibody immunoglobulin A (IgA) in the glomeruli—the tiny filtering units of the kidney. This deposition triggers inflammation, which can gradually impair the kidneys’ ability to filter waste and excess fluid.

• Who it affects: Most patients are adolescents or young adults, with the peak incidence between ages 15‑30. Males are slightly more often affected than females (approximately 1.3‑1.5 : 1 ratio).
• Prevalence: IgA nephropathy is the most common primary glomerulonephritis worldwide, accounting for 30‑40 % of biopsy‑proven glomerular diseases in Asia, 20‑30 % in Europe, and 10‑15 % in North America (Mayo Clinic, 2023; KDIGO 2021).
• Geographic variation: Higher rates are reported in East Asian countries (Japan, China, Korea), suggesting genetic and environmental influences.

Symptoms

Symptoms can be subtle early on and often go unnoticed until routine urine tests reveal abnormalities. The clinical picture varies from isolated hematuria to rapidly progressive renal failure.

• Hematuria (blood in urine): The hallmark sign. Often visible as “tea‑colored” or “cola‑colored” urine, especially after an upper‑respiratory infection. Microscopic hematuria may be the only finding on routine dipstick.
• Proteinuria (protein in urine): Ranges from mild (<1 g/day) to nephrotic‑range (>3.5 g/day). Persistent proteinuria is a predictor of disease progression.
• Edema: Swelling of the ankles, feet, or around the eyes, typically due to fluid retention from impaired kidney function.
• Hypertension: Elevated blood pressure develops in ~30‑40 % of patients and can accelerate kidney damage.
• Flank pain: Rare, but some patients experience dull pain in the sides of the lower back.
• Decreased urine output: May occur in advanced stages or during an acute flare.
• Fatigue, loss of appetite, and nausea: Nonspecific symptoms reflecting accumulation of waste products (uremia) in later disease.
• Episodes of gross hematuria after infections: Often follows a sore throat or sinus infection, reflecting the immune‑mediated nature of the disease.

Causes and Risk Factors

IgA nephropathy is considered an immune‑mediated disease; the precise trigger is not fully understood, but several mechanisms and risk factors have been identified.

Pathophysiology

• Abnormal IgA1 molecules: Patients produce galactose‑deficient IgA1 that tends to form immune complexes.
• Deposits in glomeruli: These complexes lodge in the mesangial area, activating complement (especially the alternative pathway) and causing inflammation.
• Genetic predisposition: Genome‑wide association studies have linked HLA‑DQ, -DR, and several non‑HLA loci (e.g., CFHR1‑CFHR3 deletion) to higher risk.

Risk Factors

• Family history of IgA nephropathy or other autoimmune kidney disease.
• Asian or Mediterranean ancestry (higher prevalence).
• Frequent mucosal infections (respiratory or gastrointestinal) that stimulate IgA production.
• Co‑existing conditions such as celiac disease, inflammatory bowel disease, or hepatitis C.
• Smoking – associated with faster progression to end‑stage renal disease (ESRD).

Diagnosis

Diagnosing IgA nephropathy requires a combination of clinical suspicion, laboratory testing, imaging, and, importantly, a kidney biopsy.

Initial Evaluation

• Urinalysis: Detects hematuria and proteinuria.
• Quantitative protein measurement: 24‑hour urine collection or spot urine protein‑to‑creatinine ratio.
• Blood tests: Serum creatinine, estimated glomerular filtration rate (eGFR), and complete metabolic panel to assess kidney function.
• Blood pressure assessment: Hypertension may be an early clue.

Kidney Biopsy

The definitive test. Light microscopy shows mesangial proliferation; immunofluorescence reveals dominant IgA deposits in the mesangium; electron microscopy confirms the location and characteristics of the immune complexes.

Additional Tests

• Complement levels (C3, C4) – usually normal but can be low in atypical cases.
• Serologic screening for hepatitis B/C, HIV, and ANA to exclude secondary causes.
• Genetic counseling may be offered for families with multiple affected members.

Staging & Prognostic Tools

Oxford Classification (MEST‑C score) evaluates mesangial hypercellularity (M), endocapillary proliferation (E), segmental sclerosis (S), tubular atrophy/interstitial fibrosis (T), and presence of crescents (C). This helps predict renal outcome and guide therapy (KDIGO 2021).

Treatment Options

Treatment aims to slow progression, control blood pressure, reduce proteinuria, and manage complications. Therapy is individualized based on proteinuria level, eGFR, and histologic findings.

Medications

• Renin‑Angiotensin System (RAS) Blockade: ACE inhibitors (e.g., lisinopril) or ARBs (e.g., losartan) are first‑line to control blood pressure and reduce proteinuria. Goal: <130/80 mm Hg and proteinuria <0.5 g/day.
• Immunosuppressive therapy:
  • Corticosteroids: Prednisone 0.5–1 mg/kg/day for 2–6 months, tapering based on response. Shown to reduce proteinuria in patients with >1 g/day proteinuria.
  • Cytotoxic agents: Azathioprine or mycophenolate mofetil (MMF) used as steroid‑sparing agents.
  • Tonsillectomy plus steroid bursts: Some Japanese studies suggest benefit, but evidence remains mixed.
• Fish‑oil (omega‑3 fatty acids): 2–4 g/day may modestly lower proteinuria and inflammation (Cleveland Clinic, 2022).
• Blood pressure adjuncts: Calcium‑channel blockers (especially non‑dihydropyridine) can be added if ACE/ARB alone insufficient.

Procedures

• Plasmapheresis: Considered for rapidly progressive IgA nephropathy with crescent formation, especially when combined with high‑dose steroids.
• Dialysis: Initiated when eGFR <15 mL/min/1.73 m² or symptomatic uremia develops.
• Kidney transplantation: Viable for ESRD; recurrence in the graft occurs in 20‑30 % of cases but usually does not preclude long‑term graft function.

Lifestyle & Supportive Measures

• Low‑salt diet (≤2 g sodium/day) to aid blood pressure control.
• Protein intake of 0.8 g/kg/day (moderate restriction) if proteinuria is high.
• Weight management and regular aerobic exercise (150 min/week) to improve cardiovascular health.
• Smoking cessation – reduces progression risk.
• Vaccinations: Hepatitis B, influenza, COVID‑19, and pneumococcal vaccines (per CDC guidelines) to prevent infections that may trigger flares.

Living with Immunoglobulin A Nephropathy

Successful management combines medical therapy, self‑monitoring, and psychosocial support.

Self‑Monitoring

• Check blood pressure at home daily; keep a log for the nephrologist.
• Urine dipstick weekly for protein/hematuria – report sudden changes.
• Track weight; >2 kg (≈4.5 lb) increase over 48 hours may signal fluid retention.

Dietary Tips

• Emphasize fruits, vegetables, whole grains, and healthy fats (olive oil, nuts).
• Limit processed foods, sugary beverages, and high‑phosphorus items (soft drinks, cheese).
• Stay well‑hydrated, but follow fluid restrictions if advised by your doctor (often <2 L/day in advanced CKD).

Emotional & Social Health

• Join support groups (e.g., National Kidney Foundation patient forums).
• Consider counseling or stress‑reduction techniques (mindfulness, yoga) – chronic illness can increase anxiety and depression.
• Keep up with employment or schooling; disclose the condition only as needed.

Regular Follow‑up

Typical schedule: every 3–6 months for stable disease, more frequently if proteinuria or eGFR deteriorates. Labs should include serum creatinine, eGFR, urinalysis, and lipid profile.

Prevention

Because IgA nephropathy has a strong intrinsic component, true primary prevention is limited. However, steps can reduce the risk of triggering flares or slowing progression:

• Prompt treatment of upper‑respiratory or gastrointestinal infections (e.g., antibiotics for streptococcal pharyngitis).
• Maintain optimal blood pressure and glycemic control (if diabetic).
• Avoid nephrotoxic agents: non‑steroidal anti‑inflammatory drugs (NSAIDs), contrast dyes, and certain antibiotics without hydration.
• Adopt a heart‑healthy lifestyle: regular exercise, balanced diet, and smoking avoidance.
• Vaccination adherence to lower infection‑related immune activation.

Complications

If uncontrolled, IgA nephropathy can lead to serious health problems.

• Chronic kidney disease (CKD) progression: Approximately 25‑30 % reach ESRD within 20 years of diagnosis (KDIGO 2021).
• Hypertension: Can become resistant to standard therapy.
• Cardiovascular disease: CKD amplifies risk of myocardial infarction and stroke.
• Thrombotic microangiopathy: Rare, but can cause sudden kidney function loss.
• Anemia: From reduced erythropoietin production.
• Bone‑mineral disorders: Phosphorus retention and vitamin D deficiency leading to secondary hyperparathyroidism.
• Pregnancy complications: Worsening proteinuria, hypertension, and risk of pre‑eclampsia in affected women.

When to Seek Emergency Care

---

**Sources:** Mayo Clinic. “IgA Nephropathy (Berger Disease).” 2023.
KDIGO Clinical Practice Guideline for Glomerulonephritis. 2021.
National Kidney Foundation. “IgA Nephropathy.” 2022.
Cleveland Clinic. “Kidney Disease – Treatment Options.” 2022.
CDC. “Vaccines for People with Kidney Disease.” 2024.
NIH National Institute of Diabetes and Digestive and Kidney Diseases. “IgA Nephropathy.” 2023.