Laboratory Monitoring for Multiple Myeloma
For patients with multiple myeloma, comprehensive laboratory monitoring should include complete blood count, serum protein electrophoresis with immunofixation, quantitative immunoglobulins, serum free light chains, 24-hour urine protein electrophoresis with immunofixation, serum calcium, creatinine, albumin, beta-2 microglobulin, and lactate dehydrogenase. 1
Initial Diagnostic Laboratory Panel
Blood Tests - Core Parameters
- Complete blood count (CBC) with differential and platelet count to assess for anemia and cytopenias 1, 2
- Serum protein electrophoresis (SPEP) and serum immunofixation electrophoresis (SIFE) to detect and quantify monoclonal proteins 1
- Quantitative immunoglobulins (IgG, IgA, IgM) to track disease progression and response to treatment 1
- Serum free light chain (FLC) assay with kappa/lambda ratio to screen for myeloma and monitor disease response 1, 3
Blood Tests - Prognostic and Staging Markers
- Beta-2 microglobulin for prognostic assessment and International Staging System classification 1, 4
- Serum albumin for nutritional status, prognosis, and staging 1, 4
- Lactate dehydrogenase (LDH) to evaluate tumor burden and prognosis 1, 4
Blood Tests - End-Organ Damage Assessment
- Serum calcium to evaluate for hypercalcemia (CRAB criteria) 1, 4
- Blood urea nitrogen (BUN), serum creatinine, and electrolytes to assess renal function 1, 5
Urine Tests
- 24-hour urine collection for total protein to evaluate renal function and detect monoclonal proteins 1
- Urine protein electrophoresis (UPEP) and urine immunofixation electrophoresis (UIFE) to detect and quantify monoclonal proteins in urine 1, 4
Critical caveat: A 24-hour urine collection cannot be replaced by a morning urine sample, and serum FLC assay cannot completely replace 24-hour UPEP for monitoring patients with measurable urinary M-proteins 1, 3. Urine-free light chain assay should not be performed 1.
Bone Marrow Evaluation
- Bone marrow aspirate and/or biopsy to confirm diagnosis and evaluate plasma cell infiltration 1
- Cytogenetics (metaphase karyotype) and fluorescence in situ hybridization (FISH) to detect chromosomal abnormalities including del(17p), t(4;14), and t(14;16) for prognostic assessment 1, 4
Standard metaphase cytogenetics should be included despite low yield (20%) as it provides useful prognostic information by separating hyperdiploid from nonhyperdiploid patients 4.
Ongoing Monitoring During Treatment
Disease Response Assessment
- Serial serum protein electrophoresis and immunofixation to track M-protein levels 4
- Serum free light chain measurements for monitoring response, particularly in light chain and oligosecretory myeloma 3
- Quantitative immunoglobulins to assess disease burden 1
- 24-hour urine protein electrophoresis for patients with measurable urinary M-proteins 3
Organ Function Monitoring
- Complete blood count to monitor for treatment-related cytopenias 1
- Serum creatinine and electrolytes to assess renal function, especially important as renal impairment can cause false elevations in free light chains 1, 5
- Serum calcium to monitor for hypercalcemia 1
Important Clinical Considerations
Approximately 3% of patients may have nonsecretory myeloma with neither serum nor urine proteins detectable, making serum free light chain assay particularly valuable in these cases 1.
Renal impairment causes decreased clearance of both kappa and lambda free light chains, potentially leading to false elevations that must be interpreted in clinical context 1.
After quantifying the involved light chain, use the same test for serial measurements to ensure accurate relative quantification and proper monitoring 3.
The combination of beta-2 microglobulin and serum albumin forms the International Staging System, which is more convenient and reproducible than the older Durie-Salmon classification 4. When combined with cytogenetic findings from FISH analysis, this creates the Revised International Staging System for comprehensive prognostic assessment 2.