Electrophoretic methods – electrophoresis and immunofixation
Reproducibility of the results, even for the same commercial method, although gradually improving as the studies advance, it is still insufficient, particularly for low concentrations and clearly inferior to that of nephelometry and turbidimetry. Collaboration is required with producers to achieve a necessary better standardization of electrophoretic methods in general.
The sensitivity of commercial Electrophoresis (EPh) and Immunofixation (IFX), on the samples examined, is inferior to nephelometry and turbidimetry. Detection limit should be comparable to those of immunochemical methods (around 0.5 mg/dl)
Immunochemical methods – nephelometry and turbidimetry
Reproducibility of results, in all studies performed, is confirmed as very good, even for low concentrations with all the reagents used.
Sensitivity is very good, both with reagents for “Total” Light Chains (Bound and Free Light Chains) and those for Free Light Chains.
Expression of the “Total” Light Chain result is formally different between Behring and Beckman on a 3.33 factor. Uniformity would be convenient.
Meetings held after the experiments have allowed the two “most advanced” groups to formalize some “Operational Recommendations” drafts:
Their document proposes some base characteristics which the methods and protocols used for BJP qualitative and quantitative determination should comply with.
Their document integrates the above and complementing it with two proposals:
- mask for the report
- assessment proposal for quantitative determination
Considerations for the report
Given the focus multiplicity and different characteristics of the routine methods used, it has been considered convenient that the laboratory report should:
- clearly indicate the use of a “Screening method” and in which case, detail the need of a “confirmation test” in the event of a positive result
- include information on sample type and methods used, particularly on their sensitivity, to achieve a starting point base for comparing the results obtained from the different laboratories
A specific report example, contemplating these considerations, is that proposed by the “Liguria” commission:
Test Name: Bence Jones Protein study First level test: Sample: random urine, 24h urine, etc. Method: EPh, Nephel., etc. (sensitivity <insert sensitivity here> mg/dl) Result: [_] Negative [_] Confirmation test needed (Waiting time: <insert waiting time here>) Confirmation test: Sample: random urine, 24h urine, etc. Method: IFX (detail characteristics) (sensitivity <insert sensitivity here> mg/dl) Result: <insert result here>
Other “positive effects”
Other positive effects obtained thanks to the strategy adopted with multicentric studies are:
- Better “state-of-the-art” knowledge and comparison of the participating laboratories
- Evidencing methods have turned out to be not very reliable and subsequent abandon: Total Proteins
- Progressive improvement of the characteristics of the methods used
- Advances in the BJP study uniformity
- Availability of samples verified in the multicentric works and consequently the possibility of objective comparison of the different methods available
- Possibility of applying and expanding the same strategy and work methodology adopted to subsequent studies