English: Levels of estradiol (E2) (pg/mL), progesterone (P4) (ng/mL), luteinizing hormone (LH) (IU/L), and follicle-stimulating hormone (FSH) (IU/L) with 2-mg oral micronized estradiol valerate tablets (Progynova, Schering) taken 3 or 4 times per day in premenopausal women (bottom plot). The normal menstrual cycle in a control group of premenopausal women is also shown (top plot). The time of blood collection after sublingual estradiol administration was not specified.

Some relevant literature excerpts:

• "The E2 concentration achieved with the oral route is sufficient to prime the endometrium, in spite of the rapid metabolism through the enterohepatic circulation, and if necessary, oestradiol valerate may be given sublingually to bypass it.9 Higher plasma concentrations of E2 are achieved than with the oral route, using the same dosages. As with the oral route, there is an increase in the oestrone (E1):E2 ratio."
• "[...] oral E2 therapy may not always be so effective in suppressing ovulation in some patients, especially in the young cyclic woman (Fig. 3). In an attempt to bypass the enterohepatic circulation, where most of the orally absorbed E2 is quickly metabolised, we used the sublingual route and obtained higher circulating levels with good cycle control (Fig. 4).9"
• "Effective cycle control can be achieved in cycling women either by giving LH-RHa and then oestrogens, or by use of oestrogen alone, provided it is given by a route that results in effective circulating levels (eg, sublingually)."

Sources of the values/information:

• (July 1990). "Oocyte donation and surrogacy". Br. Med. Bull. 46 (3): 796–812. DOI:10.1093/oxfordjournals.bmb.a072432. PMID 2207608.
• (May 1989). "Oocyte donation in 61 patients". Lancet 1 (8648): 1185–7. DOI:10.1016/S0140-6736(89)92762-1. PMID 2566746.