Evaluation of the Siemens Healthineers Atellica TSTII testosterone assay in the CDC HoSt-TT program

Standardized testosterone measurement is essential for diagnosing hypogonadism, infertility, endocrine disorders, and monitoring therapy. The CDC Hormone Standardization Program for Total Testosterone (HoSt-TT) evaluates assay performance against ID-LC-MS/MS using clinically relevant concentrations. This study assesses the Atellica IM TSTII assay compliance to HoSt-TT criteria and its correlation with LC-MS/MS.

Analytical performance of Atellica IM TSTII and method comparison studies using HoSt-TT certification samples were analyzed, evaluated, and stratified by sex. Comparisons of TSTII TT to LC-MS/MS and calculated vs measured free testosterone (FT) were performed and analyzed using remnant patient samples, with FT calculated (Vermeulen method, ISSAM calculator).

HoSt-TT vs Atellica IM TSTII assay results demonstrated average bias within ±6.4%, with OLS regression slopes of 1.02-1.06, r ≥ 0.98. TSTII demonstrated repeatability (2.18% CV), within-lab precision (3.46% CV), and overall total analytical error of 18.3% (IQR 11.6-31.6%). Furthermore, comparing TT on the TSTII to LC-MS/MS (LDT) using native patient samples, resulted in strong fits (slope = 0.9798, r = 0.991); and calculated FT correlated well with equilibrium dialysis/LC-MS/MS (slope = 0.9530, r = 0.965).

The TSTII assay is CDC HoSt-TT certified, has strong alignment to LC-MS/MS, and shows good correlation of calculated FT with equilibrium dialysis/LC-MS/MS. Although LC-MS/MS remains the reference method for testosterone quantification, particularly at low concentrations, CDC HoSt certification of the TSTII assay supports its potential suitability for measuring testosterone concentrations in women and children within defined analytical and clinical contexts.