Bioavailable testosterone assay constitutes a major improvement in clinical laboratory practice compared with the classic total testosterone assay for the identification of patients with partial androgen deficiency. It is also clear that clinical laboratories are not faced with obvious markers of primary hypogonadism but have to contribute to identifying a more subtle hypogonadal condition that does not involve testosterone uniquely; it probably involves a more complex endocrine condition with multiple components. In the near future, other markers may appear that may improve the diagnosis and treatment of men with partial androgen and other deficiencies.
