Quantification of Testosterone (t) by 8 Immunoassays and by Liquid Chromatography -Tandem mass Spectrometry (lc -msms) in Normal and Hirsute Women: A Multicenter Study

Objective: To compare T results in normal and hirsute women, obtained by different laboratories employing the same or different methods, including an in-home RIA, and the gold standard method LC-MS/MS. In addition, T results were referred to a curve obtained by 6 different pools that had been prepared on the basis of LC-MS/MS results. Design: Prospective study Setting: Hormone Determination Laboratory, Hospital Italiano, La Plata, and private practice of each participant laboratory. Patient(s): Blood samples were obtained from 78 individuals sorted into 3 groups, namely, normal men (n:39), normal women (n:24) and hirsute women (n:15) Interventions(s): None Main Outcome Measure(s): To evaluate if the results obtained in each lab for each serum sample by the methods currently employed in our country are significantly different from those obtained by LC-MS/MS (Gold standard) Result(s) One out of the 24 NW showed high T values by LC - MS/MS. In each lab, except in 1 (Architect) T results of this serum sample were normal. Two out of the 15 hirsute patients showed normal T values (LC - MS/MS). Method and number of labs -shown between brackets- and percentages of normal T results (false negatives) are described for each method as follows: Chemiluminescence: Axsym - Abbott (Axn) - (3) 85, Architect - Abbott - (Arch); (2) 70; Immulite - Siemmens - (IMM); (2) 42; Electrochemiluminescence - Elecsys - Roche- ((EQL); (4) 52; Fluorescent enzymatic - Vidas - Bio-Merieux - (Vidas) (1) 69; Manual coated tube radioimmunoassay (RIA): RIA - Siemmens Coat-a-Count (RIA S); (3) 64; RIA - DSL Inc (RIA DSL); (1) 31; RIA - DIASource - (DiaS); (1) 31; and in-Home RIA (in-H) (1) 12. Statistically significant differences were obtained between different methods and against LC MS/MS. In-H method is the one that comes closest to 1 on the Weighted Deming regression and closest to zero on the SD intercept, (standard deviation of the constant in the straight line equation) indicating that the values match those obtained by LC - MS/MS. The values recorded by the various methods employed showed no significant modifications when plotted against a secondary standard curve. Conclusion(s) This indicates that the techniques in current use in our area underestimate hyperandrogenemia in these patients. Discrepancies are not due to the various calibration curves proposed in the corresponding commercial kits. The fact that the In-H technique affords finer results while employing a larger serum volume suggests that the disparities among the various commercial methods result from their limited sensitivity to the sample volumes they process. No financial conflicts of interest exist. El diagnostico de hiperandrogenemia requiere la demostracion de niveles aumentados de Testosterona Total (TT) en suero. Los inmuno ensayos comerciales dan resultados divergentes a niveles bajos de TT como los obtenidos en mujeres. Valoramos los niveles de TT en 24 mujeres normales (MN) y 15 hirsutas (MH) en 18 laboratorios por metodos comunmente empleados en nuestro medio, Quimioluminiscencia: Axsym - Abbott (Axn)- (3 ), Architect - Abbott - (Arch); (2); Immulite - Siemmens - (IMM); (2); Electroquimioluminiscencia - Elecsys - Roche- ((EQL); (4); Enzimatico acoplado a fluorescencia Vidas - Bio-Merieux - (Vidas) (1), Radioinmunoiensayo en tubo recubierto (RIA): RIA - Siemmens (RIA S); (3) 64; RIA - DSL Inc (RIA DSL); (1) 31; RIA - DIASource - (DiaS); (1) 31; y un metodo desarrollado en uno de los laboratorios (in-H) (1).El numero entreparentesis indica elnumero de laboratorios que emplearon la misma tecnica,y comparamos los resultados por LC MS/MS. Comparativamente a LC MS/MS los niveles fueron en todas las muestras significativamente mas bajos por AXS y en 18 de las 24 MN por DiaS. En 7 casos; 3 por RIA S, 2 por IMM y 1 por EQL y Arch los valores de TT fueron superiores al limite superior de sus respectivos metodos. En todos los casos se obtuvo una gran variacion entre los mismos y con diferentes metodos. Trece de las 15 MH tuvieron niveles altos de TT por LC MS/MS. De las MH con TT aumentada de acuerdo a la determinacion por LC MS/MS entre el 12 y el 85 % de las mismas por los distintos metodos fueron normales, indicando que en la mayoria de los metodos habitualmente utilizados en nuestro medio subvaloran la hipernadrogenemia en estas pacientes. Estas diferencias se hacen mas notorias a niveles mas bajos de TT (Se obtuvieron valores normales en el 71 % de los casos con valores de TT entre 0.47 y 0.74 ng/ml y en el 38 % de los casos, con niveles de TT mayor a 0.98 ng/ml). En 9 muestras se determino la TT empleando una curva en el rango de 0.21 a 6.44 ng/ml preparada con de una mezcla de 78 sueros cuyos valores fueron obtenidos por LC MS/MS. No se obtuvo una modificacion significativa de los valores indicando que la diferencia entre los distintos metodos no es debida a las diferentes curvas de calibracion de los kit comerciales. En conclusion ninguno de los metodos mayormente empleados en nuestro medio son aceptables para la evaluacion de niveles menores a 1.5 ng/ml.