From the Guidelines
Multiple myeloma is typically indicated by several key laboratory abnormalities, including elevated serum protein with an M-spike on serum protein electrophoresis (SPEP), elevated free light chains with an abnormal kappa/lambda ratio, and immunoglobulin abnormalities, as well as complete blood count, renal function tests, and serum calcium level, as recommended by the most recent guidelines 1. The most important labs for diagnosing multiple myeloma include:
- Elevated serum protein with an M-spike on serum protein electrophoresis (SPEP)
- Elevated free light chains with an abnormal kappa/lambda ratio
- Immunoglobulin abnormalities (often elevated IgG, IgA, or IgM)
- Complete blood count, which may show anemia
- Renal function tests, which often reveal elevated creatinine and BUN due to kidney damage from light chain deposition
- Serum calcium level, which may be elevated due to increased bone resorption
- Bone marrow biopsy, which can show greater than 10% clonal plasma cells, is diagnostic
- Additional findings may include elevated LDH, low albumin, and elevated ESR
- Urine protein electrophoresis may show Bence Jones proteinuria (free light chains) These laboratory abnormalities reflect the underlying pathophysiology of multiple myeloma, which involves the proliferation of malignant plasma cells that produce abnormal immunoglobulins, leading to end-organ damage including bone lesions, renal impairment, anemia, and hypercalcemia (the CRAB criteria) 1. Some of the key tests that should be carried out during follow-up of myeloma patients include:
- Full blood count
- Serum and urine electrophoresis
- Serum-free light chain (sFLC) determination
- Creatinine and calcium tests
- In cases of bone pain, whole-body low-dose CT (WBLD-CT), MRI or PET-CT should be carried out to detect new bone lesions 1.
From the Research
Laboratory Features of Multiple Myeloma
The following laboratory features are indicative of possible multiple myeloma:
- Anemia, which was seen in roughly half of the diagnosed cases, most of which was normocytic normochromic anemia 2
- High erythrocyte sedimentation rate (ESR), which was seen in 65.3% of cases 2
- Increased neutrophil-to-lymphocyte ratio (NLR), which was seen in 29.7% of cases 2
- Hyperproteinemia, which was seen in 30% of cases 2
- Low albumin/globulin (A/G) ratio, which was seen in 54.2% of cases 2
- Hypercalcemia, which was seen in 11.3% of cases 2
- Serum creatinine level of >2.0 mg/dL, which was seen in 27.2% of cases 2
- Increased β2-microglobulin, which was seen in 67% of cases 2
- Monoclonal bands, which were seen in 44 cases (95.7%) 2
- Bence Jones protein, which was positive in 50% of cases 2
Diagnostic Workup
The diagnostic workup for multiple myeloma should include:
- Complete blood count with differential 3
- Serum chemistries 3
- Creatinine, lactate dehydrogenase, and beta2-microglobulin tests 3
- Immunoglobulin studies 3
- Skeletal survey 3
- Bone marrow evaluation 3
- Serum protein electrophoresis (SPEP) 2, 4, 5
- Serum free light chain (FLC) measurements 6, 4
Monitoring Disease Progression
Serum FLC concentrations can be used to follow the disease course in nearly all multiple myeloma patients, as they fall more rapidly in response to treatment than intact immunoglobulin G (IgG) and show greater concordance with serum beta2 microglobulin concentrations and bone marrow plasma cell assessments 6