Hormone replacement with estradiol: conventional oral doses result in excessive exposure to estrone

Alternative Medicine Review, March, 2005 by Patrick N. Friel, Christa Hinchcliffe, Jonathan V. Wright

The median age of the sample was 54 years (span 43-80). Fifteen women had hysterectomies. Twenty-seven women took progesterone (24 orally and three transdermally). In each case, estradiol doses were stable for one month or longer. The median estradiol dose was 0.5 mg/day (span 0.025-2.0 mg/ day). Twenty-one women took estriol in addition to estradiol.

Materials and Methods

Steroid analysis was performed using standard methods. Steroids were isolated from urine by solid phase extraction (C18 columns, United Chemical Technologies; Bristol, PA), eluted with methanol, and the methanolic extract was evaporated to dryness. The residue was reconstituted in acetate buffer, hydrolyzed overnight with sulfatase/beta-glucuronidase, and extracted with ethyl acetate after internal standard addition. The ethyl acetate extract was evaporated to dryness, and the methyloxime/trimethylsilyl (MOX/ TMS) derivatives of the steroids were prepared. The final derivatized extracts were dissolved in hexane, washed with de-ionized water, and an aliquot of the hexane phase was injected into the gas-chromatographmass spectrometer (GC-MS).

The GC-MS system included an Agilent 6890 GC with a 7683 Autosampler, an Agilent 5973N MSD, and an Enhanced MSD Chemstation data system. A 30 m x 0.25 mm ID, 0.25 micron film thickness dimethylpolysiloxane column was used, with helium (1.9 mL/min) as the carrier gas. Analytes were separated during a 32-minute temperature program, and the estrogens were identified and quantified using selected ion monitoring. with three ions for each analyte. Calibration was performed with derivatized standards prepared from pure analytical reference materials (Steraloids: Newport, R.I.). The laboratory's reference ranges for urinary estrogen excretion are presented in Table 1. (12)

Results

Urinary concentrations of estradiol and estrone were related to estradiol dose in a linear fashion. Linear regression of urinary estradiol concentration as a function of estradiol dose resulted in a coefficient of determination of [r.sup.2] = 0.917 (p<0.001). Linear regression of urinary estrone concentration as a function of estradiol dose resulted in a coefficient of determination of [r.sup.2] = 0.870 (p<0.001).

Urinary estradiol excretion as a function of estradiol dose is presented in Figure 1. The fraction of the estradiol dose excreted unchanged in the urine was 10 [ or -] 4 percent (mean [ or -] SD). At estradiol doses up to 0.5 mg/ day, urinary estradiol excretion values were within the reference range for non-pregnant, premenopausal women.

Urinary estrone concentrations as a function of estradiol dose are shown in Figure 2. The fraction of the estradiol dose excreted as estrone was 30 [ or -] 9 percent (mean [ or -] SD). In this case, doses of 0.25 mg/day or higher were associated with estrone excretion rates that exceed reference range values for non-pregnant, premenopausal women. In the 14 women who took estradiol without estriol, estriol excretion amounted to 6 [ or -] 4 percent (mean [ or -] SD) of the estradiol dose.