What is the best course of action for a patient with a history of post-infectious glomerulonephritis, presenting with elevated CRP and WBC count, normal renal function, and no proteinuria, while being treated with terbinafine?

Management of Post-Infectious Glomerulonephritis with Elevated Inflammatory Markers

This patient with a history of post-infectious glomerulonephritis showing elevated CRP (200) and WBC (13,000) but normal renal function and no proteinuria requires antibiotic therapy to eliminate residual streptococcal antigens, supportive management of inflammation, and close monitoring—while terbinafine should be continued with caution and liver function monitoring. 1

Immediate Assessment and Antibiotic Therapy

Administer penicillin (or erythromycin if penicillin-allergic) immediately, even without evidence of active infection, to decrease the antigenic load. 2, 1 This is critical because streptococcal antigens can persist and drive ongoing immune complex formation. 3

• The elevated CRP (200) and WBC (13,000) indicate active inflammation, which may represent either residual immune response or concurrent infection requiring treatment 1
• Cephalosporins (first-generation like cephalexin or third-generation like ceftriaxone) are appropriate alternatives if there are concerns about beta-lactamase producing organisms or non-anaphylactic penicillin allergy 1
• During outbreaks, systemic antimicrobials help eliminate nephritogenic strains of Streptococcus pyogenes from the community 1

Terbinafine Management Decision

Continue terbinafine but monitor liver function tests weekly for the next 4 weeks, given the elevated inflammatory markers and potential hepatotoxicity risk. 1

• The normal renal function (RFT within limits) and absence of proteinuria indicate the glomerulonephritis is not currently active from a renal standpoint 1, 3
• Terbinafine does not require dose adjustment for normal renal function 4
• However, the elevated CRP suggests systemic inflammation that could theoretically increase hepatotoxicity risk with terbinafine, warranting closer monitoring 1

Supportive Care Protocol

Restrict dietary sodium to <2.0 g/day and monitor blood pressure at every visit. 2, 1, 4

• Even without current proteinuria, sodium restriction helps prevent hypertension development, which occurs in 45% of post-infectious glomerulonephritis patients long-term 5
• Monitor for fluid overload signs (edema, weight gain) and treat with diuretics if they develop 1, 4
• Target blood pressure <120 mmHg systolic using standardized office measurement 4

Monitoring Schedule

Measure serum creatinine, eGFR, urinalysis with microscopy, and CRP every 2 weeks until CRP normalizes, then monthly for 3 months. 1, 4

• Check C3 complement levels now and repeat at 8-12 weeks—persistently low C3 beyond 12 weeks requires kidney biopsy to exclude C3 glomerulonephritis 1
• Monitor for proteinuria development (albumin-to-creatinine ratio) as this would indicate disease reactivation 1, 4
• A ≥40% decline in eGFR from baseline over 2-3 years serves as a surrogate outcome measure for kidney failure 2, 4
• Assess for hematuria with red blood cell casts, which would indicate active glomerular inflammation 1, 6

Red Flags Requiring Escalation

Perform urgent kidney biopsy if any of the following develop: 1

• Rising serum creatinine or declining eGFR by >30% from baseline 1
• Development of nephrotic-range proteinuria (>3.5 g/day) 1
• Persistent hematuria with red blood cell casts 1, 6
• C3 complement levels remaining low beyond 12 weeks 1

Consider corticosteroids only if crescentic glomerulonephritis is documented on biopsy or if rapidly progressive glomerulonephritis develops (doubling of creatinine over 1-2 months). 2, 1 The evidence for corticosteroids in post-infectious glomerulonephritis is anecdotal and limited to severe crescentic disease. 2, 1

Infection Prevention During Treatment

Administer pneumococcal vaccine if not previously given, ensure influenza vaccine is current, and provide herpes zoster vaccination (Shingrix). 2, 4

• Screen for tuberculosis, hepatitis B, hepatitis C, HIV, and syphilis if clinically appropriate given the elevated inflammatory markers 2
• Do not start prophylactic trimethoprim-sulfamethoxazole unless high-dose corticosteroids or other immunosuppression is initiated 2, 4

Common Pitfalls to Avoid

• Do not assume the elevated CRP and WBC are solely from post-infectious glomerulonephritis—rule out concurrent bacterial infection, endocarditis, or other systemic infections 2, 7
• Do not withhold antibiotics waiting for culture confirmation—treat empirically to reduce antigenic load 2, 1
• Do not start immunosuppression based on elevated inflammatory markers alone without biopsy-proven crescentic disease or rapidly progressive renal dysfunction 2, 1
• Do not discontinue terbinafine prematurely unless liver function tests become abnormal or renal function deteriorates 4