What is the initial treatment approach for patients with IgA (Immunoglobulin A) nephropathy according to the KDIGO (Kidney Disease: Improving Global Outcomes) guidelines?

Initial Treatment Approach for IgA Nephropathy According to KDIGO Guidelines

The primary focus of management for IgA nephropathy (IgAN) should be optimized supportive care, with ACE inhibitors or ARBs as first-line therapy for all patients with proteinuria >0.5 g/day. 1

Risk Assessment and Stratification

Before initiating treatment, assess the risk of progression by evaluating:

• Proteinuria level (key prognostic indicator)
• Blood pressure
• eGFR at diagnosis and during follow-up
• Pathological features (Oxford MEST-C score) 2

Consider using the International IgAN Prediction Tool for more accurate risk assessment rather than relying solely on proteinuria levels 3.

Supportive Care (First-Line Treatment)

Blood Pressure Management

• Target BP <130/80 mmHg if proteinuria <1 g/day
• Target BP <125/75 mmHg if proteinuria ≥1 g/day 1

Renin-Angiotensin System (RAS) Blockade

• For proteinuria >1 g/day: Long-term ACE inhibitor or ARB treatment (Grade 1B) 1
• For proteinuria 0.5-1 g/day: ACE inhibitor or ARB treatment (Grade 2D) 1
• Titrate ACE inhibitor or ARB to maximum tolerated dose to achieve proteinuria <1 g/day (Grade 2C) 1

Lifestyle Modifications

• Dietary sodium restriction (<2.0 g/day)
• Weight normalization
• Smoking cessation
• Regular exercise 1

Second-Line Treatment for High-Risk Patients

For patients with persistent proteinuria ≥1 g/day despite 3-6 months of optimized supportive care and eGFR ≥50 ml/min/1.73 m²:

• Consider a 6-month course of corticosteroid therapy (Grade 2C) 1

The corticosteroid regimen may include:

• IV bolus methylprednisolone (1g for 3 days) OR
• 6-month oral prednisone regimen starting with 0.8-1 mg/kg/day for 2 months 1

Important Considerations and Caveats

• Do not use corticosteroids combined with cyclophosphamide or azathioprine unless there is crescentic IgAN with rapidly deteriorating kidney function 1
• Do not use immunosuppressive therapy in patients with eGFR <30 ml/min/1.73 m² unless there is crescentic IgAN 1
• Fish oil supplementation may be considered for persistent proteinuria ≥1 g/day despite optimized supportive care 1, 2
• SGLT2 inhibitors show promise in recent studies and may be considered as additional therapy, particularly in patients with reduced eGFR 1, 2
• Monitor closely for adverse effects of therapy, particularly in patients with eGFR <50 ml/min/1.73 m² 2

Special Clinical Scenarios

• IgAN with minimal change disease: Treat as for minimal change disease with standard steroid regimen 1
• IgAN with acute kidney injury and macroscopic hematuria: Provide supportive care; consider kidney biopsy if no improvement after 5 days 1
• Crescentic IgAN (>50% crescents with rapidly progressive deterioration): Consider steroids and cyclophosphamide, similar to ANCA vasculitis treatment 1

Regular monitoring of proteinuria, renal function, blood pressure, and hematuria is essential to assess treatment response and adjust therapy accordingly, with the goal of reducing proteinuria to <1 g/day as a surrogate marker of improved kidney outcomes 2.