Table 7.

Specimen types preferred for protein electrophoresis and other associated methods.

Test	Sample type	Comment
Serum protein electrophoresis and IFE	Serum preferred	Plasma contains fibrinogen that can obscure a paraprotein and not allow its accurate quantification; fibrinogen can cross-react with serum FLC antisera on IFE
Serum FLC	Serum preferred
Urine protein electrophoresis and IFE (testing for BJP) and including urine total protein and urine creatinine	Random urine (1st morning void) or 24-hour urine BJP is detected down to 20 mg/L without pre-concentration of urine, and down to 10 mg/L with pre-concentration	Monoclonal FLC in urine (BJP) should not be measured by immunoassay as values are overestimated due to the presence of polyclonal FLC
Immunoglobulins	Serum (preferred) or plasma	Also see cryoglobulin
Cryoglobulin	Serum collected and handled at 37 °C	Loss of cryoglobulin if sample collection and handling are not done at 37 °C and any precipitated cryoglobulin is not resolubilised prior to sample analysis

IFE, immunofixation; FLC, free light chain; BJP, Bence Jones protein