Symptomatic Multiple Myeloma
A patient presenting with anemia, bone pain, and kidney problems has symptomatic multiple myeloma, characterized by end-organ damage meeting CRAB criteria (hypercalcemia, renal insufficiency, anemia, and bone lesions). 1, 2
Diagnostic Classification
This clinical triad definitively indicates symptomatic (active) multiple myeloma rather than smoldering myeloma or MGUS, because the patient exhibits clear end-organ damage. 1, 3
Key Distinguishing Features
The presence of all three symptoms confirms CRAB criteria fulfillment:
- Anemia: Normochromic, normocytic with hemoglobin <10 g/dL or ≥2 g/dL below normal, manifesting as weakness and fatigue 1, 2
- Bone pain: Indicates lytic lesions, severe osteopenia, or pathologic fractures from osteoclastic bone destruction 1, 2
- Renal insufficiency: Serum creatinine >2 mg/dL or creatinine clearance <40 mL/min, often from light chain cast nephropathy 1, 4
Why This is NOT Smoldering Myeloma or MGUS
Smoldering multiple myeloma (SMM) requires serum monoclonal protein ≥3 g/dL and/or bone marrow plasma cells ≥10% but specifically lacks any CRAB criteria or end-organ damage. 1, 3 This patient clearly has end-organ damage, excluding SMM.
MGUS requires serum monoclonal protein <3 g/dL, bone marrow plasma cells <10%, and absence of end-organ damage. 1, 3 Again, the presence of anemia, bone pain, and renal problems excludes this diagnosis.
Required Diagnostic Confirmation
To confirm symptomatic multiple myeloma, the following must be documented:
- ≥10% clonal plasma cells on bone marrow examination or biopsy-proven plasmacytoma 1, 5, 6
- Evidence of end-organ damage attributable to the plasma cell disorder (already present clinically) 1, 5
Essential Laboratory Workup
- Serum and urine protein electrophoresis with immunofixation to identify monoclonal protein 3, 4
- Serum free light chain assay with kappa/lambda ratio 3, 4
- Complete blood count confirming anemia 3, 4
- Serum creatinine and calcium levels documenting renal dysfunction 3, 4
- Bone marrow aspiration and biopsy with CD138 staining to quantify plasma cells 3, 4
Imaging Requirements
- Skeletal survey or whole-body low-dose CT to document lytic bone lesions 1
- MRI of spine if skeletal survey is negative or spinal cord compression is suspected 4, 7
Critical Diagnostic Pitfalls to Avoid
Elderly patients may have confounding conditions that mimic myeloma: 1
- Mild renal insufficiency from diabetes or hypertension (not myeloma-related) 1
- Anemia from iron, B12, or folate deficiency, or myelodysplastic syndrome 1
- Osteoporosis with compression fractures (long-standing progressive osteoporosis argues against active myeloma; sudden onset indicates active disease) 1
- Hypercalcemia from hyperparathyroidism rather than myeloma (check PTH levels) 1
However, the combination of all three symptoms (anemia, bone pain, AND kidney problems) in the context of a plasma cell disorder strongly indicates symptomatic myeloma requiring immediate treatment. 1, 2, 8
Treatment Implications
Treatment must be initiated immediately because this patient has active myeloma fulfilling CRAB criteria. 1, 3 Patients with smoldering myeloma or MGUS do not require immediate treatment, but symptomatic myeloma demands urgent intervention. 1, 3
The specific treatment regimen depends on transplant eligibility, but the presence of end-organ damage mandates starting therapy without delay. 1, 5, 6