2002, Harry W. Daniell
Conclusions: Commonly prescribed opioids in sustained-action dosage forms usually produce subnormal sex hormone levels, which may contribute to a diminished quality of life for many patients with painful chronic illness.
Daniell HW. Hypogonadism in men consuming sustained-action oral opioids. J Pain. 2002 Oct;3(5):377-84. doi: 10.1054/jpai.2002.126790. PMID: 14622741.