here is a little read about var htpa surpression
http://jcem.endojournals.org/cgi/content/full/84/8/2705
Short-Term Oxandrolone Administration Stimulates Net Muscle Protein Synthesis in Young Men1
Melinda Sheffield-Moore, Randall J. Urban, Steven E. Wolf, J. Jiang, Don H. Catlin, David N. Herndon, Robert R. Wolfe and Arny A. Ferrando
Departments of Surgery (M.S.-M., S.E.W., D.N.H., R.R.W., A.A.F.), Anesthesiology (R.R.W.), and Internal Medicine (R.J.U., J.J.), University of Texas Medical Branch, and Shriners Burn Hospital for Children (D.N.H., R.R.W.), Galveston, Texas 77550; and the Department of Molecular and Medical Pharmacology, University of California, Olympic Analytical Laboratory (D.H.C.), Los Angeles, California 90025
...Total serum T concentrations were within normal physiological range on day 0 (449 ± 35 ng/dL) and day 3 (441 ± 44 ng/dL) of OX treatment. However, by day 5, total serum T concentrations were significantly reduced (282 ± 45 ng/dL; P < 0.05) below day 0 and day 3 values (Fig. 3)...Figure 3. Total androgen concentration. Total serum T (hatched portion) and OX (black portion) concentrations in five young men on days 0, 3, and 5. *, T decreased significantly from days 0 and 3 to day 5 (P < 0.05).