Iron status in Danish women aged 35-65 years. Relation to menstruation and method of contraception

Abstract

Iron status was assessed by serum (S-) ferritin and hemoglobin (Hb) in a population survey comprising 883 non-gravid Danish women in age cohorts of 35, 45, 55, and 65 years. Premenopausal women (n = 676) had lower S-ferritin, median 42 micrograms/l, than postmenopausal women (n = 207), median 80 micrograms/l (p < 0.0001). Of premenopausal women, 12.1% had S-ferritin < or = 20 micrograms/l (i.e. depleted iron stores), and 35.6% S-ferritin of 21-40 micrograms/l (i.e. small iron stores). Corresponding figures in postmenopausal women were 0.5% and 13.2%. Premenopausal blood donors (n = 88) had lower S-ferritin than non-donors (p < 0.001). In premenopausal women, S-ferritin levels were strongly dependent on the duration of menstrual bleeding (p < 0.0001), which in turn was related to the method of contraception. Women (n = 64) using hormonal contraceptives (the pill) had menstrual bleeding of shorter duration than those (n = 511) not using pills or intrauterine devices (IUD), who in turn had bleeding of shorter duration than those (n = 101) using IUD. Median S-ferritin in pill users was 62 micrograms/l, in those not using pills or IUD 42 micrograms/l, and in IUD users 36 micrograms/l. S-ferritin values < 40 micrograms/l (i.e. small and depleted iron stores) were seen in 25% of pill users, in 48% of those not using pills or IUD, and in 61% of IUD users.(ABSTRACT TRUNCATED AT 250 WORDS)

PIP: A sampling study was undertaken to evaluate the effect of menstruation and method of contraception on iron status, especially iron deficiency, in 883 randomly selected Danish women aged 35, 45, 55, and 65 years old. The women underwent clinical examination and related detailed medical histories, including blood donation activities within the past 5 years, method of contraception, duration of menstrual bleeding, and menopausal status. Fasting blood samples were frozen and analyzed by radioimmunoassay within 6 months. Iron depletion was defined as serum ferritin levels or=20mcg/l; iron stores were considered small or reduced at 21-40mcg/l and normal or replete at values 40mcg/l. When serum ferritin was depleted and hemoglobin was 121g/l, iron deficiency anemia was diagnosed. Median serum ferritin was 42mcg/l in premenopausal vs. 80mcg/l in postmenopausal (p0.0001). 88 premenopausal women were blood donors, and their serum ferritin (33mcg/l) was significantly lower than in nondonors (43mcg/l, p0.001). 12.1% of premenopausal women vs. 0.5% of postmenopausal women and 18.2% of premenopausal blood donors vs. 11.3% of nondonors had serum ferritin or=20mcg/l. Hemoglobin values were similar for donors and nondonors. Premenopausal women, however, had slightly, but significantly, lower hemoglobin levels than postmenopausal women. (p0.001), a difference which persisted even between women with identical ferritin levels. 30 (7.4%) premenopausal and 6 (4.8%) postmenopausal women had hemoglobin values 121g/l. Iron deficiency anemia was found in 12 (3%) premenopausal women who had a longer duration of menstrual bleeding than the nonanemic women. None of these deficient women currently used oral contraceptives or an IUD. 639 women provided information on duration of menstrual bleeding; oral contraceptive users had the shortest duration and IUD users the longest. In addition, ferritin levels were highest in present and former users of oral contraceptives, lower in those who currently used other methods, and lowest in current IUD users. Iron stores can be quickly exhausted in a large majority of premenopausal women, which means that guidelines for dietary iron intake and supplementation should take the special needs of members of a population into consideration.