Pembrolizumab Can Cause Increased Creatinine Through Immune-Mediated Nephritis
Yes, pembrolizumab can cause increased serum creatinine, primarily through immune-related nephrotoxicity, though this is uncommon (occurring in <3% of patients). The most important mechanism is immune-mediated acute interstitial nephritis (AIN), which requires early recognition and treatment to prevent permanent kidney damage 1, 2, 1.
Primary Mechanism: Immune-Mediated Nephritis
The FDA drug label explicitly lists nephritis as an immune-mediated adverse effect of pembrolizumab 3. Multiple guidelines consistently identify nephritis as a recognized immune-related adverse event (irAE) across different cancer types 1, 4, 2, 1.
The renal toxicity manifests in several distinct patterns:
- Acute Interstitial Nephritis (AIN) - most common histologic finding 5
- Acute Tubular Injury (ATI) - second most common pattern 5
- Minimal Change Disease (MCD) - less common glomerular involvement 5
- Anti-GBM disease - rare but severe presentation 6
Clinical Presentation and Timing
In a nephrology referral center case series, pembrolizumab-induced nephropathy occurred with an incidence of 1.77% (12 of 676 treated patients) 5. The median time to presentation was 9 months after treatment initiation (range 1-24 months), though cases can occur earlier 5.
Key clinical features include:
- Acute kidney injury (most common presentation)
- Proteinuria (may occur with or without AKI)
- Usually isolated kidney dysfunction without systemic symptoms
- Can be severe enough to require dialysis in rare cases 5
Important Confounding Factor: Hypothyroidism
A critical diagnostic pitfall: Pembrolizumab-induced hypothyroidism can cause reversible increases in serum creatinine without true kidney injury 7. This occurs because:
- Hypothyroidism reduces creatinine generation from muscle
- Serum creatinine rises paradoxically despite normal kidney function
- Serum cystatin C remains normal, distinguishing this from true AKI 7
- Levothyroxine treatment normalizes creatinine levels 7
This distinction is crucial because it prevents unnecessary kidney biopsies and inappropriate steroid treatment 7.
Diagnostic Approach
When creatinine rises during pembrolizumab therapy:
- Check thyroid function immediately - hypothyroidism is among the most common irAEs (13% in KEYNOTE-040) 4
- Measure serum cystatin C - if normal with elevated creatinine, suspect hypothyroidism rather than true nephropathy 7
- Urinalysis with microscopy - look for proteinuria, hematuria, cellular casts
- If true AKI suspected: Consider kidney biopsy before initiating steroids to confirm diagnosis 5
Management Strategy
For confirmed immune-mediated nephritis:
- Discontinue pembrolizumab immediately 5
- Initiate corticosteroids - most effective treatment for AIN 5
- Monitor for recovery - most patients improve with steroids and drug withdrawal 5
- Rechallenge is high-risk - one patient experienced more severe recurrence upon reintroduction 5
For hypothyroidism-induced creatinine elevation:
- Treat with levothyroxine - normalizes both thyroid and renal function 7
- Pembrolizumab can be safely resumed after thyroid function stabilizes 7
Monitoring Recommendations
Based on consensus guidelines for head and neck cancer (applicable across tumor types), evaluate patients at least monthly during treatment for signs of adverse events 4. For renal monitoring specifically:
- Baseline creatinine before each treatment cycle
- Prompt evaluation of any creatinine increase
- Include thyroid function testing in routine monitoring
- Consider cystatin C if creatinine rises with normal urinalysis
Rare but Severe Presentations
Anti-GBM disease represents a rare but life-threatening complication, presenting with rapidly progressive glomerulonephritis and crescentic changes on biopsy 6. This requires aggressive treatment with:
- Plasma exchange
- High-dose corticosteroids
- Cyclophosphamide
- Consider rituximab 6
Despite aggressive treatment, outcomes can be poor, particularly in patients with advanced cancer and baseline renal impairment 6.
Clinical Context
The overall benefit-risk profile remains favorable - pembrolizumab demonstrates significant survival benefits across multiple cancer types 8. Renal toxicity, while important to recognize, is substantially less common than other irAEs such as hypothyroidism (13-35%), fatigue (38%), and diarrhea (27-54%) 4, 8.
The key to optimal outcomes is early detection through routine monitoring and rapid differentiation between true nephrotoxicity requiring immunosuppression versus hypothyroidism-induced creatinine elevation requiring only thyroid hormone replacement.