Andropause may be related to the slow but steady reduction of the production of the hormones testosterone and dehydroepiandrosterone in middle-aged men, and the consequences of that reduction. It is also associated with a decrease in Leydig cells. A steady decline in testosterone levels with age (in both men and women) is well documented.
Unlike "menopause", the word "andropause" is not currently recognized by the World Health Organization and its ICD-10 medical classification. While the words are sometimes used interchangeably, hypogonadism is a deficiency state in which the hormone testosterone goes below the normal range for even an aging male.