By contrast, nandrolone has higher molar potency at the androgen receptor but is inactivated by 5 reduction and is minimally aromatizable (44–47), making it a prototype pure androgen (i.e. nonamplifiable, nonaromatizable). The minimal effect of nandrolone on the prostate, which contains high levels of 5 reductase, confirms a previous study of nandrolone in dialysis patients (48)
Source: doi: 10.1210/jc.2002-021827