What blood work is required for IgA (Immunoglobulin A) nephropathy diagnosis and management?

Blood Work Required for IgA Nephropathy Diagnosis and Management

For IgA nephropathy diagnosis and monitoring, a comprehensive panel of blood tests should include serum creatinine, blood urea nitrogen (BUN), complete blood count (CBC), serum immunoglobulins (particularly IgA levels), complement C3, and serum albumin. 1

Initial Diagnostic Blood Work

Essential Tests

• Kidney Function Assessment

  • Serum creatinine and estimated glomerular filtration rate (eGFR) 2, 1
  • Blood urea nitrogen (BUN) 2
  • Serum electrolytes (sodium, potassium, chloride, bicarbonate) 2
  • Serum calcium and phosphate 2

• Immunologic Markers

  • Serum immunoglobulin levels (IgA, IgG, IgM) 1, 3
  • Complement C3 levels 3
  • Serum IgA/C3 ratio (ratio >3.01 suggests IgA nephropathy) 3

• Complete Blood Count

  • CBC with differential and platelet counts 2

Additional Tests

• Metabolic Parameters

  • Serum albumin 2
  • Serum uric acid 2
  • Serum and urine glucose (to assess for Fanconi syndrome) 2

• Inflammatory Markers

  • Lactate dehydrogenase (LDH) 2

Monitoring Blood Work

Regular Follow-up Tests

• Serum creatinine and eGFR (to track kidney function) 1
• Serum electrolytes 2
• Serum albumin (especially with significant proteinuria) 1
• Serum IgA levels (may help monitor disease activity) 3

Clinical Significance of Blood Tests

Diagnostic Value

• Elevated serum IgA levels (>315 mg/dl) are found in many patients with IgA nephropathy and can help distinguish it from other glomerular diseases 3
• Serum IgA/C3 ratio >3.01 has diagnostic value for IgA nephropathy 3
• Normal or reduced complement C3 may help differentiate IgA nephropathy from other forms of glomerulonephritis 3

Prognostic Value

• Reduced eGFR at diagnosis is a strong predictor of progression 1, 4
• Persistent elevation of serum creatinine (>1.5 mg/dl) indicates worse prognosis 5
• Combination of laboratory markers (including elevated serum IgA, IgA/C3 ratio, and presence of hematuria/proteinuria) correlates with disease severity 3

Important Considerations

• A kidney biopsy remains the gold standard for definitive diagnosis of IgA nephropathy, as blood work alone cannot confirm the diagnosis 1
• Blood work should be interpreted alongside urinalysis findings, particularly proteinuria and hematuria 1, 4
• The frequency of blood work monitoring should be individualized based on disease severity, with more frequent monitoring (every 3-6 months) for patients with reduced GFR or significant proteinuria 1

Common Pitfalls

• Relying solely on serum IgA levels for diagnosis - approximately 50% of patients with IgA nephropathy have normal serum IgA levels 3
• Failing to monitor kidney function regularly - IgA nephropathy can progress silently, even in patients with initially mild presentations 5
• Not considering secondary causes of IgA nephropathy that may require additional testing (liver disease, inflammatory bowel disease, celiac disease) 1
• Missing comorbidities that affect prognosis and treatment, such as hypertension and hyperlipidemia, which should be assessed and monitored 6

Remember that while blood work is essential for diagnosis and monitoring, the management decisions in IgA nephropathy are primarily based on the combination of clinical features (proteinuria, hypertension, kidney function) rather than isolated laboratory values 1, 4.