Five years with continuous combined oestrogen/progestogen therapy. Effects on calcium metabolism, lipoproteins, and bleeding pattern.

OBJECTIVE

To study the effect of long-term continuous combined oestrogen/progestogen therapy on calcium metabolism, lipoproteins, and bleeding pattern in early postmenopausal women.

DESIGN

A prospective, open, controlled study. After initial examinations, control examinations were performed every three months for the first two years and every year for the following three (two) years, with determinations of bone mass, serum lipoproteins, and bleeding pattern.

SETTING

Out-patient research clinic at The Department of Clinical Chemistry, Glostrup Hospital, Denmark.

PARTICIPANTS

Eighteen healthy women between 6 months and 3 years after a natural menopause, entered in a trial of continuous long-term hormone replacement therapy and a comparison group of 19 age-matched untreated women.

INTERVENTION

The treated group received 2 mg of 17 beta-oestradiol combined with 1 mg of norethisterone acetate orally each day continuously for 5 years with a 3 month therapy-free interval after the first 2 years. The women were investigated before treatment, then every 3 months for the first 2 years and every year for the next 3 years for determinations of bone mass, serum lipoproteins and bleeding patterns. The comparison group was followed-up in parallel for the first 4 years. Forearm bone mass was measured with single photon absorptiometry. Blood and urine samples were taken in the morning after an overnight fast and tobacco abstinence.

MAIN OUTCOME MEASURES

The effects of hormone therapy on bone mineral content in the forearm, on serum and urine indices of calcium metabolism, on serum levels of total, high (HDL-C) and low (LDL-C) density lipoprotein cholesterol, and bleeding pattern.

RESULTS

Bone mineral content in the forearm was stable during the 5 years of treatment, whereas it declined significantly averaging 10% after 4 years in the comparison group. The biochemical estimates of bone turnover decreased to premenopausal level in the hormone group, whereas they remained at a high level in the comparison group. In the hormone group total cholesterol and LDL-C decreased by 20% whereas HDL-C was virtually unchanged. The treatment was associated with minor irregular bleeding in nine women during the first 6 months of treatment, after which no bleeding was experienced.

CONCLUSION

Continuous combined oestrogen/progestogen therapy can keep early postmenopausal women free of bleeding episodes for a period of 5 years, after the first 6 months in which spotting occurs in 25%. The therapy prevented bone loss completely. The changes in serum lipoproteins were concordant with a lipid profile associated with a decreased risk of coronary heart disease.