Autonomic Manifestations of Testosterone Deficiency in Men

The investigators will recruit 40 men between the ages of 40 to 80-years-old with low testosterone. Participants will be selected among those males referred to the Texas Tech University Health Sciences Center's (TTUHSC's) Internal Medicine Endocrinology Division outpatient clinic for the study and management of testosterone deficiency and to the TTUHSC Urology Department for diagnosis and management of prostate cancer that will result in testosterone deficiency due to surgical or pharmacological castration. After recruitment, patients will have an initial standard clinical visit where aspects such as fatigue and anxiety will be investigated, followed by a full battery of autonomic testing (tilt table, heart rate response to deep breathing, Valsalva, and the Quantitative Sudomotor Axon Reflex Test (QSART). Those patients with an initial diagnosis of testosterone deficiency will be initiated on testosterone replacement (intramuscular or skin routes) as standard of care, followed by a second visit in three (3) months--after normalization of serum testosterone levels--to evaluate changes in anxiety and fatigue level, and to repeat the cardiovascular autonomic function test. Those patients with primary diagnosis of prostate cancer and normal serum testosterone levels will be evaluated a second time after confirmation of low testosterone, as described above. Standard questionnaires will be used to evaluate fatigue and anxiety. The autonomic testing of the heart will include tilt table (tilt the patient 70 degree by special designed table) and heart rate response to deep breathing, and Valsalva maneuver. Descriptive statistics will be compared between before and after treatment using different statistical methods.