Drug-Induced Kidney Injury: Renal Safety Assessment in Clinical Development and Pharmacovigilance

Drug-induced kidney injury is a broad safety concept covering functional and structural effects on the kidney. A rise in serum creatinine may signal reduced filtration, but it does not automatically prove tissue injury; conversely, cellular injury may begin before creatinine changes substantially.

Purpose and Scientific Framework

The central question is not simply whether creatinine increased. It is what changed in kidney function, whether there is evidence of kidney injury, what mechanism is plausible, and whether the medicinal product is responsible.

The assessment can draw on:

• serum creatinine and eGFR;
• urine output;
• proteinuria or albuminuria;
• haematuria and urinary sediment;
• electrolyte and acid-base abnormalities;
• cystatin C or other functional markers where appropriate;
• structural-injury biomarkers in a defined context of use;
• imaging or biopsy in selected cases;
• dose and exposure;
• concomitant nephrotoxins;
• haemodynamic and volume status; and
• alternative renal disease.

KDIGO's published AKI guideline remains the 2012 guideline; a 2026 AKI/AKD update is currently a public-review draft and should not be described as adopted guidance.

Kidney Function Versus Kidney Injury

This distinction is fundamental.

Kidney function describes filtration, excretion and homeostatic performance. Kidney injury refers to structural or cellular damage. They overlap but are not interchangeable.

A medicine can alter intrarenal haemodynamics or inhibit tubular creatinine secretion, causing an apparent reduction in filtration without structural injury. FDA regulatory-science work specifically recognises transporter-mediated creatinine increases as a potential source of false-positive nephrotoxicity signals.

Conversely, tubular injury can begin before serum creatinine rises substantially. This explains interest in more sensitive injury biomarkers, although biomarker interpretation must remain tied to a validated context of use. FDA emphasises that biomarker qualification is context-specific rather than a blanket declaration that a marker is universally diagnostic.

Major Renal Injury Phenotypes

Haemodynamic or Functional Change

Changes in glomerular filtration can occur because of altered renal perfusion or intraglomerular haemodynamics. These may be reversible and mechanistically different from cellular nephrotoxicity.

Tubular Injury

Direct or indirect tubular injury can produce rising creatinine, urinary abnormalities, electrolyte disturbances or biomarker changes. Timing, dose, urine findings and co-exposures help determine plausibility.

Interstitial Nephritis

Drug-associated interstitial nephritis may present with kidney dysfunction and variable systemic or urinary findings. Classical hypersensitivity features are neither required nor consistently present, so absence of rash or eosinophilia does not exclude the diagnosis.

Glomerular Injury

Proteinuria, albuminuria, haematuria or nephritic/nephrotic features may indicate glomerular injury. The assessment should distinguish treatment-emergent disease from pre-existing renal pathology.

Crystal, Obstructive and Vascular Injury

Some products can precipitate in urine, alter urinary flow, damage renal vasculature or contribute to thrombotic microangiopathy. Mechanistic classification is valuable because monitoring, reversibility and clinical consequences differ substantially.

Serum Creatinine and eGFR

Serum creatinine remains central to routine renal monitoring but is an imperfect injury marker. It is influenced by muscle mass, age, diet, volume status, tubular secretion and some medicines.

eGFR provides a standardised estimate of filtration but remains derived from filtration markers and therefore does not directly measure structural damage. A change in eGFR should be interpreted together with trajectory and clinical context rather than as an isolated toxicity label.

Individual-Case Assessment

A useful case review reconstructs baseline kidney status, treatment timing, creatinine/eGFR trajectory, urine findings, haemodynamic context, concomitant nephrotoxins, competing disease and recovery after interruption.

Urine Output and Urinary Findings

Urine output can provide clinically important functional information, especially in acute illness. Proteinuria, albuminuria, haematuria and sediment abnormalities may point toward glomerular, tubular or interstitial processes, but none is independently diagnostic of drug causality.

Pseudo-Nephrotoxicity

Some medicines inhibit creatinine transport and increase serum creatinine without a corresponding fall in true GFR or structural injury. The reviewer should consider alternate filtration markers, temporal pattern and known transporter pharmacology where this mechanism is plausible.

Biomarkers

Novel kidney biomarkers may help identify cellular stress or injury earlier than conventional functional markers, but their meaning depends on assay performance and context of use. FDA's biomarker framework requires interpretation within the specific qualified or accepted context rather than treating a biomarker as universally diagnostic.

Clinical-Development Assessment

Population-level renal assessment should examine more than the number of creatinine elevations. Useful analyses include:

• baseline-to-treatment shifts;
• timing and reversibility;
• dose/exposure relationships;
• treatment-versus-control patterns;
• urine abnormalities;
• electrolyte disturbances;
• serious AKI outcomes;
• discontinuations or dose reductions; and
• clinically relevant subgroups with pre-existing renal impairment.

A small reproducible functional change may have different implications from rare severe structural injury. Mechanism therefore matters as much as magnitude.

Post-Marketing Pharmacovigilance

Spontaneous reports should be followed for baseline renal function, timing, hydration/haemodynamics, infection, contrast exposure, concomitant nephrotoxins, urine findings, dialysis, recovery and rechallenge where naturally observed.

Signal assessment should group clinically coherent renal phenotypes rather than combine every report coded as renal failure. Acute tubular injury, interstitial nephritis, glomerulonephritis and haemodynamic creatinine increases may reflect different mechanisms and should not be pooled uncritically.

Product-Level Interpretation

The final question is whether the totality of evidence supports:

• a functional but non-injurious effect;
• a plausible structural nephrotoxicity;
• an immune-mediated renal reaction;
• an indirect effect mediated by another toxicity;
• an unresolved signal; or
• a better alternative explanation.

This distinction should then flow consistently into signal documentation, product information, risk management and aggregate reporting where relevant.

Practical Medical Review Sequence

1. Define the renal phenotype.
2. Establish baseline kidney function and relevant comorbidity.
3. Reconstruct creatinine/eGFR, urine output and urinary findings over time.
4. Assess haemodynamic and volume status.
5. Review concomitant nephrotoxins and alternative causes.
6. Distinguish functional change from structural injury where possible.
7. Integrate mechanism, exposure, dechallenge and other cases.
8. State the product-level conclusion with appropriate uncertainty.

Potential Failure Modes

The following are illustrative failure modes, not reported inspection findings.

Governance and Inspection Considerations

For an important renal signal, assessors may ask how the organisation distinguished kidney function from injury, obtained follow-up, considered competing nephrotoxins and haemodynamic causes, grouped cases and translated conclusions into risk management. No universal renal review committee or fixed biomarker panel is mandated.

Practical Review Checklist

1. Is the renal phenotype clear?
2. Are baseline function and trajectory known?
3. Are urine output and urine findings considered where relevant?
4. Are haemodynamics and volume status assessed?
5. Are concomitant nephrotoxins reviewed?
6. Is pseudo-nephrotoxicity considered when plausible?
7. Are biomarkers interpreted only within an appropriate context?
8. Does the final conclusion distinguish functional change, injury and causality?

Relationship With Other QPPV.com Articles

This article complements [[causality-assessment-in-pharmacovigilance]], [[signal-assessment]] and the organ-safety articles on liver, cardiac, pulmonary and neurological toxicity.

Key Takeaways

Kidney function and kidney injury are related but not synonymous.

Creatinine and eGFR are important functional measures, but neither alone proves structural nephrotoxicity. Urinary findings, clinical context, mechanism and longitudinal course are essential.

Novel biomarkers can strengthen renal assessment, but their interpretation must respect the defined context of use.

References

1. Kidney Disease: Improving Global Outcomes. KDIGO Clinical Practice Guideline for Acute Kidney Injury. 2012.
2. Kidney Disease: Improving Global Outcomes. 2026 AKI/AKD Guideline Public Review Draft. Draft, not adopted final guidance as of 9 September 2026.
3. U.S. Food and Drug Administration. Biomarkers at FDA and Biomarker Qualification Program materials. Current.
4. U.S. Food and Drug Administration. Renal Impairment in New Drug Development regulatory-science materials.
5. International Council for Harmonisation. ICH M3(R2).

Regulatory Note

The 2026 KDIGO AKI/AKD document remains a public-review draft as of 9 September 2026; the 2012 AKI guideline remains the published KDIGO guideline. FDA biomarker qualification is context-specific. Neither a particular renal biomarker panel nor a single creatinine threshold should be presented as a universal pharmacovigilance causality rule.