Sex-hormone binding globulin

Evaluation and treatment of hypogonadal men has become an important part of urological practice. Fatigue, loss of libido and erectile dysfunction are commonly reported, but non-specific symptoms of low testosterone (T) and laboratory verification of low testosterone is an important part of evaluation in addition to a detailed history and physical exam. Significant intra-individual fluctuations in serum T levels, biological variation of T action on end organs, the wide range of T levels in human serum samples and technical limitations of currently available assays have led to poor reliability of T measurements in the clinical laboratory setting. There is no universally accepted threshold of T concentration that distinguishes eugonadal from hypogonadal men, thus laboratory results have to be interpreted in the appropriate clinical setting. This review focuses on clinical, biological and technological challenges that affect serum T measurements to educate clinicians regarding technological advances and limitations of currently available laboratory methods to diagnose hypogonadism. A collaborative effort led by the American Urological Association (AUA) between practicing clinicians, patient advocacy groups, government regulatory agencies, industry and professional societies is underway to provide optimized assay platforms and evidence based normal assay ranges to guide clinical decision making. Until such standardization is commonplace in clinical laboratories, the decision to treat should be based on the presence of signs and symptoms in addition to serum T