Why wouldn't endocrinologist test for zinc when diagnosing low testosterone considering this study? http://www.ncbi.nlm.nih.gov/pubmed/8875519

No Clear Evidence: The study you cite, from 1996, has not been corroborated in subsequent follow up research. A change in practice rarely occurs from a single study's findings. The size of the sample is small as well, at 40 patients, leaving the likelihood of these results being valid low. Here is a link to some zinc studies from mayo: http://www.Mayoclinic.Com/health/zinc/ns_patient-zinc/dsection=evidence.