Inclusion Criteria:

          1. The patient must be able to provide study-specific informed consent prior to study
             entry

          2. Age ≥ 18

          3. ECOG Performance Status 0-2

          4. Pathologically proven diagnosis of prostate adenocarcinoma

          5. Patients must have metastatic prostate cancer

          6. Patients may have mCRPC or may have metastatic castration-sensitive disease.

          7. Patients must be maintained on a GnRH analogue (agonist (leuprolide, goserelin,
             triptorelin, histerelin, deslorin) or antagonist (degarelix))

          8. The patient and the investigator have decided that the next line of cancer therapy
             will be abiraterone plus prednisone and the initial dose of abiraterone will be 1000
             mg daily. Or patients may already be on abiraterone with prednisone at a dose of 1000
             mg daily along with a GnRH analogue.

          9. Lab values meeting the following criteria

               1. Total testosterone level of <50 ng/dl

               2. Total bilirubin < 2.0 X Upper Limit of Normal (ULN)

               3. Aspartate aminotransferase (AST) ≤ 3 X ULN

               4. Alanine aminotransferase (ALT ) ≤ 3 X ULN

               5. Absolute Neutrophil Count > 1.5 K/mm3

               6. Platelets > 100 K/mm3

               7. Hemoglobin ≥9.0 g/dL

               8. calculated creatinine clearance ≥ 30 mL/min

             Exclusion Criteria:

         10. History of bilateral orchiectomy

         11. History of hypopituitarism

         12. For patient not yet started on abiraterone with prednisone, uncontrolled hypertension
             (systolic blood pressure >170 mm Hg or diastolic blood pressure >100 mm Hg)

         13. Patients must not have New York Heart Association Class III or IV heart failure at the
             time of screening. Patients must not have any unstable angina, myocardial infarction,
             or serious uncontrolled cardiac arrhythmia within 6 months prior to registration

         14. Any other serious illness or medical condition that the principal investigator feels
             would make the patient a poor candidate for this study