This Wikipdia-article lists several conditions or diseases that may lead to reduced levels of alkaline phosphatase (AP).
Among them are:
- postmenopausal women receiving estrogen therapy because of aging
- taking oral contraceptives (the linked study investigated combined OCP)
I assume, in both cases the hormones themselves (estrogen, maybe also progestogen) somehow influence the AP-levels. If it is correct:
Is the reaction cascade known, that leads from the hormone(s) to the reduced AP levels?