Diagnostic testing for monoclonal gammopathies!
A tweetorial for internists to clear some confusion!
Serum protein electrophoresis(SPEP)
Urine protein electrophoresis (UPEP)
Serum immunofixation (SIFE)
Urine immunofixation (UIFE)
Serum free light chains(sFLC) (kappa/lambda)
A tweetorial for internists to clear some confusion!
Serum protein electrophoresis(SPEP)
Urine protein electrophoresis (UPEP)
Serum immunofixation (SIFE)
Urine immunofixation (UIFE)
Serum free light chains(sFLC) (kappa/lambda)
Electrophoresis (SPEP/UPEP) = how much
Charge based separation of protein on gel
Low sensitivity
May miss small monoclonal proteins and light chains
Quantifies M-protein (g/dL)
Does not qualify M-protein (IgG, IgA, IgM, IgD, IgE)
Charge based separation of protein on gel
Low sensitivity
May miss small monoclonal proteins and light chains
Quantifies M-protein (g/dL)
Does not qualify M-protein (IgG, IgA, IgM, IgD, IgE)
Immunofixation = Determines the flavor
Ab’s against the heavy chains and κ and λ light chains
Allows for identification of isotype (IgG, IgA, IgM, IgD, IgE)
Detection of small proteins missed on electrophoresis
More sensitive than SPEP
Unlike SPEP/UPEP, not quantitative
Ab’s against the heavy chains and κ and λ light chains
Allows for identification of isotype (IgG, IgA, IgM, IgD, IgE)
Detection of small proteins missed on electrophoresis
More sensitive than SPEP
Unlike SPEP/UPEP, not quantitative
Serum Free Light Chains
Clone either kappa or lambda so in monoclonal process ratio will be skewed
Free serum kappa light chains – 3.3 to 19.4 mg/L
Free serum lambda light chains – 5.7 to 26.3 mg/L
Ratio of kappa to lambda FLCs – 0.26 to 1.65
Most sensitive test
Altered in CKD
Clone either kappa or lambda so in monoclonal process ratio will be skewed
Free serum kappa light chains – 3.3 to 19.4 mg/L
Free serum lambda light chains – 5.7 to 26.3 mg/L
Ratio of kappa to lambda FLCs – 0.26 to 1.65
Most sensitive test
Altered in CKD
Conclusions
If truly concerned for monoclonal gammopathy order SPEP, IFE, light chains, +/- urine studies
Sensitivity:
FLC>IFE>SPEP
IFE determines flavor (IgG/A/M)
SPEP determines amount = g/dL
Serum immunofixation is more sensitive than SPEP
If truly concerned for monoclonal gammopathy order SPEP, IFE, light chains, +/- urine studies
Sensitivity:
FLC>IFE>SPEP
IFE determines flavor (IgG/A/M)
SPEP determines amount = g/dL
Serum immunofixation is more sensitive than SPEP
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