Monoclonal Gammopathy of Undetermined Significance

A 58-year-old man with no significant medical history is found to have an elevated total protein concentration (8.1 g per deciliter) on a routine blood chemical study. He is asymptomatic, and his physical examination is normal. Serum protein electrophoresis reveals a monoclonal spike of 2.1 g per deciliter at the gamma region; immunofixation shows a monoclonal IgG kappa protein. What further evaluation is warranted, and assuming the diagnosis of monoclonal gammopathy of undetermined significance is made, how should the patient be followed?