Lack of diurnal variation in plasma levels of androstenedione, testosterone, estrone and estradiol in postmenopausal women

J. steroid Eiochem. Vol. 34, Nos l-6, pp. 551-553, 1989 Printedin Great Britain. All rights reserved

0022-4731/89$3.00+ 0.00 Copyright 0 1989Pergamon Press plc

LACK OF DIURNAL VARIATION IN PLASMA LEVELS OF ANDROSTENEDIONE, TESTOSTERONE, ESTRONE AND ESTRADIOL IN POSTMENOPAUSAL WOMEN P . E . L@NNING,‘,*‘* M. DOWSETT,'S. JACOBS,* B. SCHEM,~ J. HARDY’ and T. J. POWLES’ ’ Department of Medicine and 2Department of Biochemical Endocrinology, Royal Marsden Hospital, London and Surrey, England and ‘Department of Oncology and Radiophysics, Haukeland Sykehus, Bergen, Norway

Summary-Plasma 4-en-androstenedione, testosterone, estradiol and estrone were measured during the day in six healthy postmenopausal women and in six breast cancer patients, three of whom received treatment with glucocorticoids. Blood samples were obtained at 8 a.m., 10 a.m., 12 noon, 4 p.m., 8 p.m. and 12 midnight. There was a considerable variation in plasma levels of all steroids during the day; for 4-en-androstenedione the mean within patient coefficient variation was 61.4%, for testosterone it was 28.9%, for estrone it was 17.8% and for estradiol it was 29.2%. While the plasma levels for all steroids tended to be higher in the morning than in the evening, the changes were not statistically significant (Friedman’s test: P > 0.10). We conclude that although a moderate diurnal variation in the plasma level of these steroids may occur, it is of a moderate magnitude compared to variations due to other causes.

INTRODUCTION

received glucocorticoid therapy (‘prednisone 10 mg b.d. or dexamethasone 4mg t.d.s.). One of the patients was a smoker, but none of the participants were heavy alcohol consumers. On the day of investigation, blood samples (20 ml) were drawn at 8 a.m., 10 a.m., 12 noon, 4 p.m., 8 p.m. and 12 midnight. The blood samples were allowed to coagulate for 1 h, centrifuged, and the serum was stored at -20°C until analysis. Estrone and estradiol were measured after organic extraction by previously described methodology [l, 21. The within and between assay coefficients of variation were: E, 6.8 and 10.7%, E, 9.4 and 12.8% respectively. Testosterone was measured using the St Thomas Hospital Kit: iodinated tracer, organic extraction. The within and between assay coefficients of varitation were 6.5 and 8.9%, respectively. Androstenedione levels were measured using the Diagnostic System Laboratories Direct Solid-Phase Kit. The within and between assay coefficients of variation were 9.8 and 12.0%, respectively.

Suppression of plasma estrogens is an effective endocrine treatment for breast cancer. This study was conducted as part of our programme of investigating estrogen disposition in breast cancer patients treated with different endocrine drugs. The aim of the study was to explore whether there is any diurnal variation in plasma levels of E, and E, as well as their precursors 4-en-A and T in postmenopausal women. If such a variation exists, that would have an impact on the design of studies of estrogen disposition. EXPERIMENTAL

Six healthy postmenopausal women and six postmenopausal women suffering from advanced breast cancer were enrolled in this study. All gave their informed verbal consent to participate. The mean age of the volunteers was 57.4 years (5460 yr), and that of the breast cancer patients was 61.5 years (35-77 yr). The young patient had had amenorrhea for more than 2 years following protracted cytotoxic treatment. Three of the breast cancer patients

RESULTS

Proceedings of the 9th International Symposium of the Journal of Steroid Biochemistry, Recenr Advances in Steroid Biochemistry, Las Palmas, Canary Islands, Spain, 28-31 May 1989. *Present address for correspondence and reprints: Department of Oncology and Radiophysics, N-5016 Haukeland Sykehus, Bergen, Norway. S.B. 34-1,611

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No difference in plasma hormone levels were found between normal postmenopausal women and breast cancer patients who did not receive glucocorticoid treatment. However, breast cancer patients on glucocorticoid treatment had low, but detectable levels of all hormones investigated. Relative variations in plasma hormone levels during the day were of the same magnitude in all groups of women investigated.

552

P. E.

INNING

Mean plasma levels of E, and E, among women receiving no glucocorticoid treatment (n = 9) were 16.3 f 8.4 pM and 165.8 f 65.1 pM at 8 a.m., respectively. Variation in plasma steroid levels relative to values obtained at 8 a.m. (relative mean with SD) for women not receiving glucocorticoid treatment are shown in Figs 1 and 2. While plasma E, tended to be higher in the morning that in the evening, the highest plasma level for E, was found at 12 noon. In contrast, plasma 4-en-A tended to be higher in the evening than in the morning; the substantial increase in relative mean plasma levels of this steorid during the day is largely due to the fact that some patients had very low levels of this hormone at 8 a.m. Random variations in plasma levels for all steroids during the day were substantial, and a Friedman test for multiple comparison revealed no significant diurnal variation in plasma steroid levels for any of the hormones investigated (P > 0.10). The mean within patient coefficients of variation for each plasma hormone during the day among all the women were 61.4, 28.9, 17.8 and 29.2% for 4-en-A, T, El and E,, respectively.

100

75

c

T

ef a!. Plasma

-

s

-501

8

T

t

I

I

I

12

16

20

24

Plasm0

A4-A

300 t

T

_

Plasma E2 Time

Fig. 2. Mean alterations ( f SD) in plasma levels of T and 4-en-A during the day in normal females and breast cancer patients receiving no glucocorticoid therapy.

DISCUSSION

8

6

12

16

20

24

1

T

i% 6 5 Plosma

\I,T 1

El

i-1-i

Time

Fig. 1. Mean alterations (k SD) in plasma levels of E, and E, during the day in normal females and breast patients receiving no glucocorticoid therapy.

cancer

A diurnal variation in plasma El but not plasma E, has been suggested for males [3]. One study suggested a modest diurnal variation in plasma estrogens for postmenopausal women when paired comparisons were made between values obtained in the morning and the afternoon [4]. In this study we found no statistically significant diurnal variation in plasma androgen or estrogen levels. Our results, however, do not necessarily conflict with the findings of Vermeulen [4]. The diurnal variation in plasma E, found by these investigators was moderate. Our data do not exclude that a moderate diurnal variation could exist, but mechanisms other than a diurnal variation (such as food ingestion) may have a stronger influence on plasma steroid levels. Importantly, the results of this study show a substantial, random variation in plasma levels of different androgens and estrogens during the day in postmenopausal women. Such variations in plasma steroid levels should be considered when plasma steroid production rates are evaluated, and such variations may partly explain why different studies

Diurnal estrogen variation in postmenopausal women

trying to evaluate relative contribution of different pathways for estrogen production have reported conflicting results [S].

Acknowledgements-P.

E. Lsnning is a recipient of a senior fellowship from Overledge Dr M. D. Carl Johan Unger-Vetlesen Charitable Fund.

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2. Dowsett M., Goss P. E., Powles T. J., Hutchison G.,

Brodie A. M. H., Jeffcoate S. L. and Coombes R. C.: Use of the aromatase inhibitor 4_hydroxyandrostenedione in postmenopausal breast cancer. Optimization of therapeutic dose and route. Cancer Res. 47 (1987) 1957-1961. 3. Baird D. T. and Guevara A.: Concentration of unconjugated estrone and estradiol in peripheral plasma in nonpregnant women throughout the menstrual cycle, castrate and postmenopausal women and in men. J. clin. Endocr. Metab. 38 (1974) 602-607.

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Harris A. L., Dowsett M., Jetfcoate S. L. and Smith I. E.: Aminoglutethimide dose and hormone suppression in advanced breast cancer. Eur. J. Cuncer clin. Oncol. 19 (1983) 493498.

4. Vermeulen A.: The hormonal activity of the postmenopausal ovary. .I. clin. Endocr. Metab. 42 (1976) 247-253.

5. Lonning P. E., Dowsett M. and Powles T. J. Postmenopausal estrogen synthesis and metabolism: alterations caused by aromatase inhibitors used for the treatment of breast cancer. J. steroid Biochem. (In press).