IntroductionThe plasma cell proliferative disorders are characterized by the proliferation of a single clone of plasma cells in the bone marrow and by the production of monoclonal immunoglobulins. These disorders may range from a phenotypically benign entity, monoclonal gammopathy of undetermined significance, to symptomatic myeloma with bone destruction, suppression of bone marrow function, and renal damage. The International Myeloma Working Group has established criteria for the diagnosis of plasma cell proliferative disorders. These test criteria have been adopted and/or slightly modified by other groups and are shown in Table 1. [1][2][3] In everyday practice, there is still some confusion regarding the use of standard laboratory tests that evaluate serum and urine monoclonal proteins. Furthermore, a new test, serum-free light measurement, has emerged. Over the last decade, newer imaging techniques, such as magnetic resonance imaging (MRI) and positron emission tomography-computed tomography (PET-CT), are increasingly used in the assessment of patients with multiple myeloma. In this paper, we report International Myeloma Working Group Consensus Panel recommendations for the minimal diagnostic and prognostic tests, the follow-up investigation after therapy, and the tests to be performed at relapse for patients with multiple myeloma. The Consensus Panel consisted of several physicians with a research interest in plasma cell dyscrasias who held several teleconferences, and their recommendations were presented during the 2009 International Myeloma Workshop.
Minimal diagnostic and prognostic testsInitial investigation of a patient with suspected multiple myeloma should include the tests shown in Table 2. Family history should focus on first-degree relatives with the diagnosis of hematologic malignancies, especially lymphoma, chronic lymphocytic leukemia, and plasma cell dyscrasias. Past medical history should focus on comorbid conditions that may affect treatment decisions, such as coronary artery disease, congestive heart failure, hypertension, renal disorders, liver disorders, and lung diseases. A complete blood count with differential should be ordered, and a peripheral blood smear should be evaluated in search of specific findings, such as rouleaux formation and circulating plasma cells. A complete biochemistry screen should be ordered, which includes liver function tests, renal function tests, electrolytes, calcium, and albumin.Both serum and urine should be assessed for monoclonal protein. Agarose gel electrophoresis or capillary zone electrophoresis of serum and urine is preferred to screen for the presence of monoclonal protein. However, quantitation of serum immunoglobulins by nephelometry should also be performed. Measurement of monoclonal protein both by densitometer tracing and by nephelometric quantitation is recommended. These 2 tests are complementary, and nephelometric quantitation may be particularly useful for low levels of uninvolved immunoglobulins. 4 However, it should be