Correspondence: Ruggero Dittadi, Department of Laboratory Medicine, Laboratory Analysis Unit, Regional General Hospital, ULSS12 Veneziana, Via Paccagnella 11, 30174 Mestre-Venice, Italy. Tel: +39 41965 8216. Fax: +39 4196 57557. E-mail: ruggero.dittadi@ulss12.ve.it (Received 2 February 2013; accepted 13 May 2013) ORIGINAL ARTICLE Evaluation of a sex hormone-binding globulin automated chemiluminescent assay RUGGERO DITTADI 1 , ALINE S. C. FABRICIO 2 , SILVIA MICHILIN 2 & MASSIMO GION 1 1 Laboratory Analysis Unit and 2 Regional Center for Biomarkers, Department of Laboratory Medicine, Regional General Hospital,Venice, Italy Abstract Background. Sex hormone-binding globulin (SHBG) is the main transport protein of sex steroids. This study evaluated the analytical performance of the recently developed Access SHBG assay (Beckman Coulter) and compared it with other commercial methods for the determination of serum SHBG. Clinical validation was also performed. Methods. Analytical performance including within-run and between-run imprecision was assessed for Access SHBG assay on the automated Beckman UniCel DxI800 analyzer. Linearity was assessed using five dilutions of the serum samples. For methods com- parison, SHBG levels were determined also with Immulite 2000 analyzer (Siemens Healthcare) using clinical serum sam- ples ( n = 104). For clinical validation 135 specimens from healthy subjects, pregnant women, hypothyroid and hyperthyroid patients were analyzed. Results. Total coefficients of variation were  5.5%. Linearity test showed  90% recovery for all samples and for all dilution rates. Comparison analysis (Bland-Altman difference analysis and Passing-Bablock regression) showed an acceptable agreement between selected methods. SHBG values measured by Access SHBG assay in different groups of subjects were in agreement with other clinical evidence. Conclusions. Automated Access SHBG assay appears to be a reliable and easy to perform assay, as necessary for application in routine diagnostics. Key Words: Immunoassay , SHBG, method comparison, free Testosterone, method validation Introduction Sex hormone-binding globulin (SHBG) is an 86 kDa circulating beta globulin synthesized in the liver [1] that transports and regulates the access of sex ste- roids from blood to their target tissues [2]. SHBG levels in healthy subjects are related to several variables such as diet, body mass index, insulin concentrations, age and circulating estrogens [3–5]. Furthermore, in some cases, it has been shown that SHBG is an independent predictor factor of bone mineral density [6]. Moreover, the measurement of SHBG can be an important indicator of chronic or excessive androgenic activity. In fact, decreased levels of SHBG are often observed in cases with hir- sutism, obesity and polycystic ovarian syndrome [7,8]. SHBG measurement, as recommended by The Endocrine Society [9] is also used to calculate index of bioactive fractions of testosterone, the cal- culated free testosterone (FT) and the bioavailable testosterone (bioT) [10]. With the final aim to use the test for routine diagnostic application, this study was undertaken to evaluate the analytical performance of the recently developed Access SHBG assay (Beckman Coulter Inc., Fullerton, CA, USA) on UniCel DxI800 ana- lyzer and to compare it with another automated method for SHBG assay: Immulite 2000 (Siemens Healthcare, Tarrytown, NY, USA). The concor- dance with the Immunoradiometric assay (IRMA) Orion Diagnostica was also evaluated in a subset of samples. The selection of this method is justified on the basis of its utilization to determine the algo- rithm for the FT calculation [10]. Moreover, some clinical findings were obtained. Material and methods SHBG levels were assessed by the automated Access SHBG assay (Beckman Coulter Inc., Fullerton, CA, USA), a dual-monoclonal chemiluminescent Scandinavian Journal of Clinical & Laboratory Investigation, 2013; 73: 480–484 ISSN 0036-5513 print/ISSN 1502-7686 online © 2013 Informa Healthcare DOI: 10.3109/00365513.2013.805807 Scand J Clin Lab Invest Downloaded from informahealthcare.com by Universita Statale Milano on 09/26/14 For personal use only.