It's gender specific. For females, androgens are the main trigger.
Serum hormone levels in men with severe acne
AbstractIn order to evaluate the hormonal milieu in young men with severe acne, we measured serum estradiol (E2), total testosterone (T), free testosterone (FT), dihydrotestosterone (DHT), dehydroepiandrosterone sulfate (DHEA-S), and sex hormone binding globulin (SHBG) levels in sixteen male patients aged 20-30 years with severe acne, including twelve cases of nodular-cystic acne, and in seventeen age-matched normal controls. There were no significant differences in the serum levels of T, FT, DHT, DHEA-S, or SHBG between the patients and the controls, but serum E2 was significantly higher in the patient population. Thus, the hemodynamics of serum androgens in male patients with acne do not seem to differ significantly from that of normal controls. Elevated E2 levels might affect the inflammatory response of acne vulgaris through the release of thymic hormones, as reported in the literature.
Testosterone and estradiol serum levels in acne
Abstract45 acne patients and 38 healthy subjects were assayed for serum testosterone and estradiol levels by RIA. The results showed that serum testosterone levels of male patients were normal, but serum estradiol levels were significantly higher (40%) than in healthy males.