What is the recommended evaluation and treatment approach for an adult with nephrotic syndrome?

Evaluation and Treatment of Adult Nephrotic Syndrome

Begin with renal biopsy to establish the underlying cause in adults, except when serum anti-phospholipase A2 receptor antibodies are positive (diagnostic of membranous nephropathy), and initiate supportive care with ACE inhibitors/ARBs, sodium restriction, and diuretics while determining disease-specific immunosuppressive therapy. 1, 2

Initial Evaluation

Confirm Nephrotic Syndrome Diagnosis

• Measure 24-hour urine protein (>3.5 g/day), serum albumin (<3.0 g/dL), and lipid panel to confirm the nephrotic syndrome triad of proteinuria, hypoalbuminemia, and hyperlipidemia 3, 2
• Assess for edema and document blood pressure 2

Identify Secondary Causes

• Screen for diabetes mellitus (most common secondary cause in adults), systemic lupus erythematosus, amyloidosis, hematologic malignancies, and infections (HIV, hepatitis B/C) 4, 2
• Obtain targeted serologic testing based on clinical suspicion rather than broad unguided workup 2
• Test for serum anti-phospholipase A2 receptor antibodies if membranous nephropathy is suspected—positive results are diagnostic and may obviate biopsy 4

Renal Biopsy

• Perform renal biopsy in adults to establish diagnosis unless anti-PLA2R antibodies are positive 2, 5
• Biopsy is essential to differentiate primary causes (focal segmental glomerulosclerosis, membranous nephropathy, minimal change disease) from secondary causes 1, 4
• Carefully assess for clinical and pathologic clues distinguishing idiopathic from secondary FSGS, as immunosuppression risks outweigh benefits in secondary disease 1

Disease-Specific Treatment Approaches

Focal Segmental Glomerulosclerosis (FSGS)

First-Line Corticosteroid Therapy:

• Initiate prednisone 1 mg/kg/day (maximum 80 mg) or alternate-day 2 mg/kg (maximum 120 mg) for patients with nephrotic syndrome 6
• Continue high-dose corticosteroids for minimum 4 weeks, up to maximum 16 weeks or until complete remission, whichever occurs first 1
• Taper slowly over 6 months after achieving complete remission 1
• Adult response rates are lower than children, with >50% showing steroid resistance even with prolonged treatment 1

Second-Line Therapy for Steroid-Resistant or Intolerant Patients:

• Consider calcineurin inhibitors (cyclosporine or tacrolimus) as first-line therapy for patients with contraindications to corticosteroids (uncontrolled diabetes, psychiatric conditions, severe osteoporosis) 6
• Start cyclosporine at 2 mg/kg/day, gradually increase to maximum 4 mg/kg/day based on pharmacokinetic monitoring 3
• Target cyclosporine trough levels (C0) of 125-175 ng/mL and C2 levels >500 ng/mL 3
• Continue treatment for 6-12 months to achieve maximum benefit, with response rates >70% in steroid-resistant FSGS 3, 1
• After complete remission, taper slowly (by 0.5 mg/kg/month) to minimum effective dose and maintain for 1-2 years, as relapses occur in >50% upon discontinuation 3
• If no response after 6 months (minimum 50% reduction in proteinuria), consider alternative agents 3

Membranous Nephropathy

• Risk stratify patients by proteinuria severity over 6 months: low-risk (<4 g/day), medium-risk (4-8 g/day), high-risk (>8 g/day or deteriorating renal function) 3
• Treatment decisions should focus on high-risk patients, as 20-30% achieve spontaneous remission 3

Minimal Change Disease

• Treat relapses of nephrotic syndrome per relapsing MCD recommendations in adults 1
• Adults require longer time to respond with poorer response rates compared to children 1

Universal Supportive Care

Cardiovascular Risk Reduction

• Initiate ACE inhibitors or ARBs for all patients to reduce proteinuria and provide cardiovascular protection 1, 2, 7
• Start statin therapy given significant cardiovascular morbidity and mortality risk in nephrotic patients with CKD 1
• This is particularly important in adults given variable response to immunosuppression and prolonged treatment courses 1

Edema Management

• Restrict dietary sodium and implement fluid restriction 2, 7
• Use oral or intravenous diuretics as needed for symptomatic edema 2

Thromboembolism Prevention

• Consider anticoagulation prophylaxis for high-risk patients, particularly those with membranous nephropathy and serum albumin <20 g/L 4, 8
• Thromboembolic risk increases significantly when albumin falls below 20 g/L 8

Infection Prevention

• Administer pneumococcal vaccination to reduce infection risk 8
• Prophylactic antibiotics are not currently recommended 2

Monitoring and Follow-Up

Treatment Response Assessment

• Define complete remission as proteinuria <0.20 g/day with serum albumin >35 g/L 3
• Define partial remission as proteinuria 0.21-3.4 g/day with >50% reduction from baseline 3
• Monitor renal function (GFR) closely, as it serves as the primary guide for treatment decisions 3
• Watch for steroid resistance (persistence of proteinuria despite prednisone 1 mg/kg/day for >4 months) 3

Side Effect Monitoring

• Vigilantly monitor for complications from both nephrotic syndrome and immunosuppressive agents, particularly in elderly patients with comorbidities like obesity and diabetes 1
• Steroid intolerance is more significant in adults with advanced age and comorbid conditions 1

Critical Pitfalls to Avoid

• Do not withhold immunosuppression in idiopathic FSGS with nephrotic syndrome, as it improves proteinuria and slows progression to ESRD 1
• Do not use immunosuppression in secondary FSGS, as risks outweigh benefits—focus on treating underlying cause and cardiovascular risk reduction 1
• Do not stop cyclosporine abruptly, as rapid renal function deterioration can occur even after years of treatment 3
• Do not delay biopsy in adults when diagnosis is uncertain, as this may miss the opportunity for timely immunosuppressive therapy 1