“…Burkhardt (2–4) has demonstrated changes in the specific gravity of the marrow of certain bones during the succeeding stages of life. This change is most pronounced in women during the period at which postmenopausal osteoporosis develops (5). Since both male and female sex hormones induce retention of calcium phosphate and interrupt the catabolic phase in bones (5) and the male hormone lowers nitrogen excretion, the rationale for the treatment of postmenopausal osteoporosis by the administration of sex hormones is clear (5), and the therapeutic results of such treatment have been good (6–9).…”