What are the symptoms and treatment options for post-streptococcal glomerulonephritis (PSGN) in patients with a history of valve disorders or other underlying medical conditions?

Symptoms of Post-Streptococcal Glomerulonephritis (PSGN)

Classic Clinical Presentation

PSGN characteristically presents with acute nephritic syndrome featuring hematuria (microscopic or gross), hypertension, edema, and oliguria, typically occurring 1-3 weeks after streptococcal pharyngitis or 4-6 weeks after impetigo. 1

Cardinal Symptoms

• Hematuria - Either microscopic or macroscopic (gross) hematuria with red blood cell casts on urinalysis, representing the hallmark finding 1
• Edema - Fluid retention manifesting as periorbital edema, peripheral edema, or generalized swelling due to sodium and water retention 1, 2
• Hypertension - Present in approximately 95% of patients during the acute phase, typically mild to moderate in severity 3
• Oliguria - Reduced urine output secondary to decreased glomerular filtration 2, 4
• Proteinuria - Ranging from mild to nephrotic-range proteinuria in some cases 1, 5

Timing Relative to Infection

• Pharyngitis-associated PSGN - Symptoms develop 1-2 weeks after streptococcal throat infection 1, 6
• Impetigo-associated PSGN - Longer latency period of 4-6 weeks after skin infection 1, 6

Severe Complications (Less Common)

While most cases are self-limited, certain patients develop serious complications requiring intensive management:

• Hypertensive emergencies - Severe blood pressure elevation requiring urgent intervention 2
• Congestive heart failure - Secondary to fluid overload and hypertension 2
• Severe acute kidney injury - Manifesting with significantly reduced GFR (can drop to 11.2 ml/min/1.73 m²), requiring potential dialysis 1, 5
• Rapidly progressive glomerulonephritis - Crescentic disease with rapid deterioration of kidney function 1, 2
• Uremia - In severe cases with marked kidney dysfunction 1
• Life-threatening hyperkalemia - Requiring emergent dialysis 1

Laboratory Manifestations

• Elevated serum creatinine and decreased eGFR - Indicating acute kidney injury 1
• Low C3 complement levels - The hallmark laboratory finding, with C4 typically remaining normal 1
• Elevated streptococcal antibodies - Including ASO, anti-DNAse B, and anti-hyaluronidase antibodies 1
• Metabolic acidosis - May develop with serum bicarbonate <22 mmol/L 1
• Hyperuricemia - Can be markedly elevated (up to 12.7 mg/dl in severe cases) 5

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Treatment Approach

Antibiotic Therapy

Administer penicillin (or erythromycin if penicillin-allergic) even when active infection has resolved, as the goal is to reduce antigenic load rather than treat active infection. 1

• Penicillin remains first-line antibiotic therapy 1
• Erythromycin serves as the alternative for penicillin-allergic patients 1
• Cephalosporins (first-generation like cephalexin or third-generation like ceftriaxone) are appropriate alternatives for non-anaphylactic penicillin allergy or severe infections 1, 5
• Co-amoxiclav (amoxicillin/clavulanate) provides excellent streptococcal coverage and is validated for PSGN management 1
• During outbreaks, systemic antimicrobials help eliminate nephritogenic strains from the community 1

Critical pitfall to avoid: Do not withhold antibiotics even when active infection is no longer evident—the therapeutic goal is reducing antigenic burden, not treating active infection 1

Supportive Management of Nephritic Syndrome

The cornerstone of PSGN management is supportive care focusing on hypertension control, fluid management, and monitoring for complications. 1, 2

Sodium and Fluid Management

• Restrict dietary sodium to <2.0 g/day (<90 mmol/day) as first-line intervention for both edema control and blood pressure management 1
• Monitor fluid status closely and adjust based on clinical response 1
• Use diuretics (typically furosemide) as first-line agents for managing both fluid overload and hypertension 1, 3

Blood Pressure Control

• Target systolic blood pressure <120 mmHg using standardized office measurement in adults 1
• In children, target 24-hour mean arterial pressure at ≤50th percentile for age, sex, and height by ambulatory monitoring 1
• Diuretics serve as first-line antihypertensive agents 1
• Additional antihypertensive medications may be required for adequate control 1

Monitor closely for diuretic-related adverse effects: hyponatremia, hypokalemia, GFR reduction, and volume depletion 1

Dietary Modifications

• Restrict dietary protein to 0.8-1 g/kg/day if nephrotic-range proteinuria is present 1
• Treat metabolic acidosis if serum bicarbonate is <22 mmol/L 1
• Consider treating dyslipidemia in patients with nephrotic syndrome, particularly those with cardiovascular risk factors 1

Management of Severe Cases

• Dialysis is indicated for severe acute kidney injury with uremia, refractory fluid overload, or life-threatening hyperkalemia 1, 5
• Reserve corticosteroids ONLY for severe crescentic PSGN with rapidly progressive glomerulonephritis, based on anecdotal evidence 1
• High-dose glucocorticoids and immunosuppressive therapy may be considered for crescentic PSGN, though evidence is limited 1

Critical pitfall to avoid: Do not routinely use immunosuppression—the evidence is anecdotal at best and most cases resolve spontaneously 1

Monitoring Requirements

• Regular assessment of kidney function, blood pressure, proteinuria, and hematuria 1, 7
• Monitor C3 complement levels at 8-12 weeks to confirm normalization 1, 7
• If C3 remains persistently low beyond 12 weeks, perform kidney biopsy to exclude C3 glomerulonephritis 1, 7
• Monitor serum creatinine, urinalysis with microscopy, and urine protein-to-creatinine ratio 1

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Special Considerations for Patients with Valve Disorders

While the evidence does not specifically address valve disorders in PSGN management, patients with underlying cardiac conditions require heightened vigilance:

• Aggressive fluid management is critical to prevent congestive heart failure in patients with pre-existing valve disorders 2
• Monitor more closely for fluid overload given increased cardiac vulnerability 1
• Blood pressure control becomes even more crucial to prevent cardiac decompensation 1, 3
• Consider earlier initiation of dialysis if fluid overload threatens cardiac function 1

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Prognosis

The prognosis for children with classic PSGN is excellent, with complete recovery expected in the vast majority of cases and minimal risk of chronic kidney disease. 7

• Children with epidemic/classic PSGN have outstanding long-term outcomes, with over 80% returning to premorbid kidney function 7
• Complete recovery is expected in previously healthy children 7
• Prognosis is good with early diagnosis and antibiotic treatment 7
• Most patients make full recovery even with severe renal impairment in early stages 5
• Histological resolution may take up to 9 years in adults 8

Factors Indicating Poorer Prognosis

• Persistent hypertension during disease evolution is a poor prognostic sign, contributing to glomerulosclerosis and later renal insufficiency 3
• Persistent proteinuria, hypertension, and C3 abnormalities beyond 12 weeks warrant kidney biopsy and long-term monitoring 1, 7
• Adults may have less favorable outcomes compared to children 8, 4