| Androgen deficiency in men is a syndrome characterized by a constellation of symptoms and signs and low circulating testosterone levels. Thus, the diagnosis of androgen deficiency is predicated upon the determination whether circulating testosterone level is low or normal. Rigorously established reference ranges constitute the essential basis for identifying whether the circulating levels of an analyte, such as testosterone, are normal or low. The reference ranges for testosterone have been derived previously mostly from small convenience samples, or from hospital or clinic-based patients; these approaches are limited by their inherent selection bias, as patients seeking medical care are more likely to have a disease than individuals in the general population. |
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