## Clinical Context This patient has newly diagnosed **symptomatic multiple myeloma** with all four CRAB criteria met: **C**alcium elevated (11.2 mg/dL), **R**enal dysfunction (creatinine 2.1 mg/dL), **A**nemia (Hb 8.5 g/dL), and **B**one lesions (lytic lesions in skull and pelvis). Bone marrow shows 45% plasma cells with an M-spike of 3.5 g/dL — this is unequivocal symptomatic MM requiring immediate treatment. ## Why Induction Chemotherapy is the Correct Next Step **Key Point:** In symptomatic MM with CRAB criteria, the standard of care is to initiate induction chemotherapy promptly. Delay in treatment leads to progressive organ damage. **High-Yield (Harrison's 21e, Ch. 110):** The current standard induction regimen for transplant-eligible patients is a **bortezomib-based triplet** (e.g., VRd: bortezomib + lenalidomide + dexamethasone, or VCd: bortezomib + cyclophosphamide + dexamethasone). Bortezomib is preferred in patients with renal impairment as it does not require dose adjustment for renal dysfunction. **Why not Option B (hydration + allopurinol + cardiac echo + PFTs)?** - While hydration is appropriate supportive care for hypercalcemia and renal dysfunction, it does not replace or precede chemotherapy initiation in symptomatic MM. - **Tumor lysis syndrome (TLS) is not a significant concern in MM** — unlike lymphomas or leukemias, MM cells lyse slowly and TLS prophylaxis with allopurinol is not a standard pre-treatment requirement before bortezomib-based therapy. - Cardiac echo and PFTs are **not mandatory pre-treatment requirements** before initiating bortezomib-based induction in standard practice guidelines (NCCN, IMF). These are performed selectively based on clinical indication. - Delaying chemotherapy for extensive pre-treatment workup in a patient with active organ damage (renal failure, hypercalcemia) is not evidence-based and risks further deterioration. ## Management Algorithm | Step | Action | |------|--------| | 1 | Confirm diagnosis (done: BM biopsy, SPEP, skeletal survey) | | 2 | Initiate induction: Bortezomib-based regimen (VRd or VCd) | | 3 | Supportive care: IV hydration, bisphosphonates for bone disease | | 4 | Assess transplant eligibility after 4–6 cycles of induction | | 5 | Proceed to ASCT if eligible and good response | **Clinical Pearl:** Bortezomib is the preferred proteasome inhibitor in MM with renal impairment (creatinine 2.1 mg/dL) because it is hepatically metabolized and does not require renal dose adjustment. Bisphosphonates (zoledronic acid) should be added for bone disease, with dose adjustment for renal function. **Why not Option C (immediate ASCT)?** ASCT is performed after 4–6 cycles of induction chemotherapy to achieve maximum response; it is never the immediate first step. **Why not Option D (observation)?** Observation (watchful waiting) is reserved for smoldering/asymptomatic MM. This patient has symptomatic MM with CRAB criteria — observation is contraindicated. [cite: Harrison's Principles of Internal Medicine, 21e, Ch. 110; NCCN Guidelines for Multiple Myeloma v2024]
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