What is the initial approach to treating nephritic syndrome?

Initial Approach to Treating Nephritic Syndrome

For nephritic syndrome, the cornerstone of initial treatment is identifying and treating the underlying infectious or autoimmune cause with appropriate antimicrobials or immunosuppression, while providing supportive care with antihypertensives, diuretics, and dialysis if needed. 1

Immediate Supportive Management

The initial approach differs fundamentally from nephrotic syndrome and focuses on managing the acute inflammatory glomerular injury:

• Control hypertension aggressively using ACE inhibitors or ARBs as first-line agents, targeting systolic blood pressure <120 mmHg to prevent further glomerular damage 2
• Manage fluid overload with loop diuretics (furosemide) for edema and pulmonary congestion, as nephritic syndrome typically presents with salt and water retention 3, 1
• Restrict dietary sodium to <2.0 g/day to reduce fluid retention and help control blood pressure 2, 3
• Initiate dialysis emergently if acute kidney injury progresses to uremia, severe hyperkalemia, or refractory fluid overload 1

Disease-Specific Treatment Based on Etiology

The treatment must be tailored to the specific underlying cause, as nephritic syndrome represents acute glomerulonephritis from various etiologies:

Post-Infectious Glomerulonephritis

• Administer penicillin (or erythromycin if penicillin-allergic) even in the absence of persistent infection to decrease antigenic load 4
• Provide supportive care only in most cases, as post-streptococcal GN is typically self-limited 4, 1
• Consider corticosteroids only for severe crescentic disease based on anecdotal evidence, though data are limited 4

IgA Nephropathy

• Use ACE inhibitors or ARBs at maximally tolerated doses for proteinuria control 2
• Consider corticosteroids for patients with persistent proteinuria >1 g/day despite maximal supportive therapy and preserved kidney function 1

Lupus Nephritis

• Initiate immunosuppression with corticosteroids plus cyclophosphamide or mycophenolate mofetil for proliferative forms 1, 5
• Consider anticoagulation if nephrotic-range proteinuria develops with serum albumin <20 g/L 6

ANCA-Associated Vasculitis

• Start high-dose corticosteroids immediately combined with cyclophosphamide or rituximab for induction therapy 1
• Do not delay treatment while awaiting biopsy confirmation if clinical suspicion is high, as this is rapidly progressive 1

Membranoproliferative GN

• Treat underlying cause first (hepatitis C, cryoglobulinemia, monoclonal gammopathy) 4
• Consider immunosuppression with cyclophosphamide or MMF plus low-dose corticosteroids only for idiopathic cases with nephrotic syndrome and progressive kidney function decline, limited to <6 months initially 4

Critical Diagnostic Steps to Guide Treatment

• Obtain urinalysis immediately looking specifically for dysmorphic red blood cells and red cell casts, which confirm glomerular origin of hematuria 1, 5
• Measure serum creatinine and eGFR to assess for acute kidney injury, which is common in nephritic syndrome unlike nephrotic syndrome 1, 5
• Check complement levels (C3, C4) as low levels suggest post-infectious GN, lupus nephritis, or MPGN 6, 1
• Perform kidney biopsy urgently if diagnosis is unclear or if rapidly progressive GN is suspected, as treatment differs dramatically by etiology 4, 1
• Test for ANCA, anti-GBM antibodies, ANA, and anti-dsDNA if vasculitis or lupus is suspected 6, 1

Common Pitfalls to Avoid

• Do not confuse nephritic with nephrotic syndrome - nephritic syndrome presents with hematuria, hypertension, and acute kidney injury rather than massive proteinuria and edema as the dominant features 1, 5
• Do not delay treatment for ANCA vasculitis or anti-GBM disease while awaiting biopsy, as these are medical emergencies requiring immediate immunosuppression 1
• Avoid routine albumin infusions and prophylactic anticoagulation unless nephrotic-range proteinuria develops, as these are not indicated for pure nephritic syndrome 7
• Do not use immunosuppression empirically for post-infectious GN, as most cases resolve with supportive care alone and steroids are reserved only for severe crescentic disease 4

Monitoring During Initial Treatment

• Assess urine output, blood pressure, and fluid status daily during the acute phase 1
• Monitor serum creatinine every 1-2 days to detect worsening kidney function that may require escalation of therapy or dialysis 1
• Repeat urinalysis to track resolution of hematuria and proteinuria as markers of treatment response 5
• Watch for complications including severe hypertension, pulmonary edema, and uremia requiring urgent intervention 1, 5