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Lab Studies for Multiple Myeloma


- Studies:
    - sed rate: is usually > 100 mm per hour;
    - serum electrophoresis:
         - finding of abnormal protein peak migrating w/ IgA or IgG fraction is diagnostic;
                - an protein migrating w/ IgG or IgA bond in about 90% of pts;
         - major criteria for dx:
                - monoclonal globulin spike > 3.5 g for IgG;
                - monoclonal globulin spike > 2.0 g per 100 ml for IgA
    - hypercalcemia may occur in 20-40% of patients;
         - this does not correlate with the amount of bony destruction;
         - is more common in renal insufficiency, & hence treatment may be difficult;
         - combo of calcitonin & steroids is usually effective in myeloma esp when there is renal insufficiency;
         - agents that are nephrotoxic such as plicamycin (mithramycin) should be avoided;
         - parental pamidronate (biphosphonate) is effective but should be used w/ caution in renal insufficiency;
    - alkaline phosphatase:
         - marker of osteoblast activity;
         - is usually not increased in myeloma since there is little new bone formation, which explains why bone scans appear cold;
    - anemia:
         - pts w/ diffuse disease & assoc osteopenia have fairly profound normocytic, normochromic anemia, often w/ Hct of < 30%;
    - platelet deficiency;
    - uric acid: - high level of uric acid (secondary gout);
    - renal f(x):
         - abnormal renal function;
         - lambda light chains, are nephrotoxic, & light-chain myeloma is commonly complicated by renal failure;
    - bence jones proteinuria:
         - occurs in less than 50 per cent of patients;
         - urinary immunoelectrophoresis may have substantially higher yield for IgG light chains excreted in the urine.
         - dx: monoclonal globulin spike > 1.0 g / 24 hrs for urinary light chains.