![]() ![]() As most antibodies migrate into the γ region, the monoclonal proteins are generally identifiable as a sharp peak in the γ region of the SPEP, referred to as an “M spike.” SPEP neither establishes the subtype of monoclonal protein nor confirms that an M spike represents monoclonal protein. Serum is loaded onto a medium to which an electrical current is applied, separating constituent proteins into 5 distinct regions based on electrical charge and size: albumin, α1, α2, β, and γ. The most widely used laboratory test to identify monoclonal protein is serum protein electrophoresis (SPEP). This monoclonal protein can be intact immunoglobulin or immunoglobulin fragments, such as free light chains (FLC) or less-commonly free heavy chains. The rationale for recommended monoclonal protein evaluation is highlighted in Table 1. In patients with suspected amyloidosis, both AL and ATTR amyloidosis should be considered.ĭiagnosing AL amyloidosis requires showing the presence of a clonal plasma cell dyscrasia, which starts with monoclonal protein evaluation ( 3). Given the divergent therapeutic approaches, determining the subtype of amyloidosis is of paramount importance. The most widely used ATTR amyloidosis therapeutics either reduce transthyretin production (inotersen and patisiran) or stabilize the tetramer (tafamidis) ( 2). By contrast, ATTR amyloid fibrils are misfolded monomers of transthyretin, a tetrameric protein produced by the liver that binds thyroid hormone. AL amyloidosis is typically treated with chemotherapy targeted at clonal populations of plasma cells that are responsible for producing amyloidogenic light chains. The treatment paradigm for both disorders is to reduce bloodstream concentrations of amyloidogenic protein, and the specific therapeutic approach depends on the subtype of amyloidosis. The 2 most common types of cardiac amyloidosis in the United States are AL amyloidosis and ATTR amyloidosis. Cardiac involvement is common and can result in arrhythmias or clinical heart failure events, which are often fatal ( 1). Amyloidoses are diseases in which misfolded proteins deposit in organs, interfering with normal function. ![]()
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