1. Oxymetholone converts rapidly to estrogen. False. So false. In fact oxymetholone cannot interact with the aromatase enzyme at all, and thus it cannot be converted into estrogen in any amount or at any pace.
2. Oxymetholone is not suppressive to the HPTA. Another myth. It clearly disrupts the HPTA heavily, as evidenced by the numerous studies in which it does precisely that.
3. Oxymetholone is a xenoestrogen. It's been noted that oxymethelone bears some structural similarity to estradiol and therefore hypothesized that it may possess inherent estrogenic qualities by stimulating the estrogen receptor itself instead of by converting to estrogen via aromatization. While this would seem to explain some reports of side-effects and treatment of them with selective estrogen receptor modulators literature on the topic is conspicuously absent. To date no substantial evidence has surfaced that indicates oxymetholone has any binding affinity for the estrogen receptor, although studies examining metabolites have not examined this in depth and further study is needed to rule out the possibility of estrogenic metabolites of the parent drug.
4. Oxymetholone is a progestin. Another hypothesis lacking evidence at this point. There are no examples in the literature that I could find showing clear evidence for progestagenic activity.
So how do we explain the side effects and the case reports and the popular folklore? The short answer is that right now we don't. Explanations range from a rumor-driven placebo effect in the doping community to alterations of glucose metabolism to metabolites with novel actions. We need to keep studying to find out.