## Assessment of Melphalan Toxicity Risk ### Why Renal Function is Critical **Key Point:** Melphalan is an alkylating agent that undergoes hepatic metabolism but is renally excreted. Impaired renal function significantly increases systemic exposure and toxicity risk, particularly hematologic and gastrointestinal toxicity. **High-Yield:** Baseline creatinine clearance (CrCl) assessment via 24-hour urine collection or Cockcroft-Gault formula is mandatory before high-dose melphalan because: - Dose reduction is required if CrCl < 30 mL/min - Risk of severe mucositis, myelosuppression, and secondary malignancies increases with impaired clearance - Melphalan accumulation in renal failure can be life-threatening ### Melphalan Pharmacokinetics in Renal Impairment | Parameter | Normal Renal Function | Renal Impairment (CrCl < 30) | |-----------|----------------------|------------------------------| | Clearance | 3–5 mL/min/kg | Reduced 30–50% | | Half-life | 60–90 min | Prolonged | | Toxicity Risk | Standard | High (dose reduction needed) | | Monitoring | Standard labs | Intensive hematologic monitoring | **Clinical Pearl:** In the context of autologous stem cell transplantation (ASCT), renal function assessment is part of pre-transplant evaluation because melphalan is the standard conditioning regimen, and adequate renal clearance ensures optimal pharmacokinetics and tolerability. **Warning:** Bone marrow biopsy (option B) assesses disease burden and cytogenetics for prognosis, not toxicity risk. Serum albumin (option C) and pulmonary function (option D) are general pre-treatment assessments but are NOT specific to melphalan toxicity prediction. [cite:KD Tripathi 8e Ch 62]
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