Skip to main content
. 2019 Dec 2;27(3):361–370. doi: 10.1097/GME.0000000000001463

TABLE 1.

Mean systemic estradiol levels at baseline and throughout studies of low-dose and ultralow-lose vaginal estrogen therapies measured by radioimmunoassay or another assay

Assay Dose Treatment n Study duration Mean BL (pg/mL) Mean Cmax (pg/mL) Mean Cavga (pg/mL) Mean AUC0-24 (pgh/mL) Reference
RIA 25 μg E2 tablet 59 48 wks 4.1 NR Weeks 24 & 48: 9.8 NR Weisberg et al, 200515
RIA 25 μg E2 tablet 19 12 wks 7.0 Day 1: 51 Week 12: 49 Day 1: 22 Week 12: 23 Day 1: 538 Week 12: 563 Notelovitz et al, 200216
RIA 25 μg E2 tablet 6 12 wks 7.5 20.4 Week 2: NR (15.8) Week 12: NR (16.4) 13.6 (after last tablet) Week 2: 380.0 Week 12: 392.5 Nilsson and Heimer, 199519
RIA 25 μg E2 tablet 24 14 d 9.5 Day 1: 42.8 Day 14: 21.8 Day 14: 16 (24 h) NR Nilsson and Heimer, 199220
RIA 25 μg E2 tablet (1x/wk) 17 52 wks 10.5 NR Week 2: 10.1 Week 12: 9.9 Week 52: 10.8 NR Mettler and Olsen, 199121
RIA 25 μg E2 tablet (2x/wk) 34 52 wks 9.6 NR Week 2: 9.3 Week 12: 9.6 Week 52: 11.3 NR Mettler and Olsen, 199121
RIA 25 μg E2 tablet 80 24 wks NR (≤30)b NR Week 24: 5% of women >49b NR Rioux et al, 200075
RIA 10 μg E2 tablet 23 12 wks 7.6 Day 1: 35 Week 12: 22 Day 1: 15 Week 12: 11 Day 1: 349 Week 12: 264 Notelovitz et al, 200216
RIA 10 μg E2 tablet 24 14 d 9.5 Day 1: 24.5 Day 14: 15.0 Day 14: 13, hour 24 NR Nilsson and Heimer, 199220
RIA 10 μg E2 tablet 336 52 wks 5.2 NR Week 52: 6.1 NR Ulrich et al, 201014
RIA 0.3 mg CEE cream 20 4 wks 8 (with placebo) NR 13 NR Mandel et al, 198322
RIA 7.5 μg/d E2 ring; Untreated 27 27 12 mos 3.7 (E) 4.2 (U) NR 4.2 (E2) 4.1 (U) NR Naessen and Rodriguez-Macias, 200217
RIA 7.5 μg/d E2 ring; Untreated 20 10 6 mos 4.4 (E) 3.5 (U) NR 6 mos: 5.7 (E2); 3.0 (U) NR Naessen et al, 199718
RIA 8.0 μg/d E2 ring 126 48 wks 4.4 NR Week 24: 13.3 Week 48: 5.5 NR Weisberg et al, 200515
RIA 9.0 μg/d E2 ring 222 24 wks <5.5 (UD) NR Within postmenopausal rangec NR Smith et al, 199323
RIA 6.6 μg/d E2 ring 11 84 d <12.3 (UD) Median at 2 h: 63.5 (range 29.4-158.8) Median Day 2: 19.1 Days 7, 14, 28, 84: <12.3 (UD) NR Holmgren et al, 198924
RIA 20.2 μg/d E2 ring 11 84 d <12.3 (UD) Median at 2 h: 96.4 (range 72.7-231.8) Median Day 2: 51.8 Days 7, 14, 28, 84: <12.3 (UD) NR Holmgren et al, 198924
Bioassay 10 μg E2 creamd 7 12 wks 2.0 (E2) 1-3 (U) Initial: 3.1 Week 3: 3.8 Week 12: 5.7 NR NR Santen et al, 200276
ELISA 25 μg E2 tablet 27 12 wks 7.6 NR 8.9 NR Manonai et al, 200125
IC 25 μg E2 tablet; Placebo 828 784 12 mos 15.7 (E) 14.2 (P) NR 4 mos: 17.3 (E); 15.1 (P) 12 mos: 15.5 (E); 13.8 (P) NR Simunic et al, 200377
NR 25 μg E2 tablet 48 24 wks <2.7 NR <2.7e NR Dugal et al, 200078

AUC0-24, area under the curve over 24 hours; BL, baseline; Cavg, average concentration; CEE, conjugated equine estrogens; Cmax, maximum concentration; E2, 17β-estradiol; ELISA, enzyme-linked immunosorbent assay; GC, gas chromatography; IC, immunochemical (Ortho-Clinical Diagnostics); LC, liquid chromatography; MS, mass spectrometry; MS/MS, tandem mass spectrometry; NR, not reported (for average E2 levels with NR, AUC0-24 [if reported] was divided by 24 to calculate the average); P, placebo; RIA, radioimmunoassay; U, untreated; UD, undetectable (below limit of detection).

aOr level reported but specified as Cavg.

bReported percentage of women who had levels > postmenopausal range (>49 pg/mL); basal level of ≤30 pg/mL based on inclusion criteria.

cE2 levels were in postmenopausal range (27.2-68.1 pg/mL) and below limit of detection (5.5 pg/mL) before and during (time not specified) treatment.23

dDiluted Estrace given daily during first 3 weeks then twice weekly for 9 weeks.76

eBlood E2 levels were within the normal range for postmenopausal women (<2.7 pg/mL) after 24 weeks of treatment.78