Once a monoclonal intact immunoglobulin is identified in a patient's serum, guidelines recommend that it is quantified using scanning densitometry of serum protein electrophoresis (SPE) gels (or capillary zone electrophoresis [CZE]), alongside nephelometric/turbidimetric quantitation of total immunoglobulins (Chapter 25) . The serum concentration of the monoclonal intact immunoglobulin is an important determinant in choosing the correct method to monitor disease course. Whilst it is preferred that monoclonal proteins are monitored by densitometric quantification, in cases where small monoclonal proteins are obscured by other serum proteins (e.g. transferrin), nephelometric measurements may be more accurate .
Additionally, international guidelines recommend performing sFLC analysis at presentation as it provides important prognostic information (Chapter 20). This also gives a baseline measurement for monitoring oligosecretory patients (serum monoclonal protein <10 g/L and urine monoclonal protein <200 mg/24 hours ) and all patients to allow early detection of relapse by FLC escape (Chapter 18) .