Valor diagnóstico de la electroforesis de proteínas y cadenas ligeras libres en suero en el mieloma múltiple / Diagnostic value of serum protein electrophoresis and free light chains in the multiple myeloma's diagnosis

RESUMEN Fundamento: La electroforesis de proteínas y las cadenas ligeras libres en suero son técnicas utilizadas en el diagnóstico del mieloma múltiple. Sin embargo, la utilidad diagnóstica de ambas pruebas puede variar según el método empleado y condiciones reales del medio donde se realicen. Objetivo: Determinar el valor diagnóstico de la electroforesis de proteínas y de las cadenas ligeras libres en suero en el mieloma múltiple. Metodología: Se realizó un estudio retrospectivo de los parámetros electroforesis de proteínas en suero y cadenas ligeras libres en suero a 43 pacientes con diagnóstico de mieloma múltiple por evaluación de la médula ósea. La electroforesis de proteínas se realizó por el método convencional de separación de proteínas sobre papel de acetato de celulosa y para las cadenas ligeras libres se aplicó un ensayo inmunoturbidimétrico en el que se usó un analizador químico (Cobas 311). Se calcularon 7 parámetros que evaluaron la exactitud diagnóstica. Resultados: Todos los parámetros que evaluaron la exactitud diagnóstica estuvieron dentro de los intervalos de confianza en ambas pruebas. Conclusiones: La electroforesis de proteínas y las cadenas ligeras libres en suero son ensayos de gran utilidad en el diagnóstico del mieloma múltiple y se deben utilizar en conjunto para la mayor captación posible de casos.

ABSTRACT Background: Protein electrophoresis and serum free light chains are techniques used in the diagnosis of multiple myeloma. However, the diagnostic utility of both tests may vary according to the method used and the actual conditions of the environment where they are performed. Objective: To determine the diagnostic value of protein electrophoresis and serum free light chains in multiple myeloma. Methodology: A retrospective study of serum protein electrophoresis parameters and serum free light chains was conducted in 43 patients diagnosed with multiple myeloma by bone marrow evaluation. Protein electrophoresis was completed by the conventional method of protein separation on cellulose acetate paper and for free light chains an immunoturbidimetric assay was applied in which a chemical analyzer (Cobas 311) was used. Seven parameters were calculated to evaluate diagnostic accuracy. Results: All parameters assessing diagnostic accuracy were within confidence intervals in both tests. Conclusions: Protein electrophoresis and serum free light chains are very useful assays in the diagnosis of multiple myeloma and should be used in conjunction for the highest possible approval of cases.

Methodological evaluation on serum free light chains detected by immunoturbidimetry / 国际检验医学杂志

Objective To perform the methodological evaluation on Beckman Immage 800 automatic special protein analyzer for determining serum freeκ,λlight chains (sFLC) .Methods The Beckman Immage800 automatic special protein analyzer was used to quantitatively detect sFLC values for investigating its precision and accuracy ,analyzing its detecting range ,interference and residual contamination rate ,meanwhile verifying its reference intervals .Results The low and high values of within‐run precision coefficients of variation(CV) forκsFLC were 7 .84% and 2 .95% respectively ;which of between‐run precision CV were 7 .38% and 5 .57% re‐spectively .The within‐run precision CV for λFLC were 4 .59% and 3 .94% respectively ,which of between‐run precision CV were 3 .97% and 2 .01% respectively ;bias for detecting theκFLC andλFLC fixed quality serum and the target values was less than 5% , when the analytical detection ranges of κFLC andλFLC were 10 .8-128 .0 mg/L and 10 .1-121 .0 mg/L ,a value was 0 .95-1 .05 , r2 ≥0 .98;the carry‐over rates of κFLC andλFLC were 0 .411% and 0 .216% respectively .The interference test results showed that when free hemoglobin≤342 .0 μmol/L ,conjugated bilirubin ≤342 .0 μmol/L ,hemoglobin≤5 g/L and chyle ≤2 400 turbidness , which had no influence on sFLC results ;among 40 healthy subjects undergoing the physical examination ,1 case of κFLC detection results exceeded the reference interval recommended by the manufacturer ,while theλFLC detection values in these 40 cases were all within the reference interval recommended by the manufacturer .Conclusion The main analytical performance of the Beckman Im‐mage800 automatic special protein analyzer for detecting sFLC meets the requirements of quality objectives and can provides the sci‐entific and precise evidence of diagnosis and treatment for clinic .