Immunosuppressant medication Mechanism of immunosuppressant action Endocrine dysfunction Tacrolimus (FK506)/ Cyclosporine Calcineurin inhibition 1.  Hyperglycemia: Beta cell toxicity, decreased insulin secretion and insulin sensitivity PTDM [16,21,22,26,28,29]. 2.   Hypogonadism/oligospermia: rarely [53].      3.   Low bone density: Cyclosporine has strong evidence while TAC has equivocal effects [60-62,64]. Sirolimus (rapamycin) mTOR inhibition 1.  Hyperglycemia: Insulin resistance and beta cell toxicity [14-16,37]. 2.  Primary hypogonadism in men and rarely reduced sperm counts [54-58]. 3.  May impair fracture healing [67].

Table 1: Summary of effects of TAC and SIR on endocrine system