Normal iron levels in women
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Normal Iron Levels in Women: An Overview
Serum Ferritin and Hemoglobin Levels in Women
Serum Ferritin Levels by Age
Serum ferritin, a key indicator of iron stores in the body, varies significantly with age in women. A study of 1359 Danish women aged 30 to 60 years found that median serum ferritin levels increased with age. For 30- and 40-year-old women, the median serum ferritin was 38 µg/L, while it rose to 54 µg/L in 50-year-old women and further to 84 µg/L in 60-year-old women1. This trend suggests that iron stores tend to accumulate as women age.
Hemoglobin Levels by Age
Hemoglobin (Hb) levels also show age-related variations. In the same cohort, median Hb levels were 137 g/L for 30- and 40-year-old women and slightly higher at 140 g/L for 50- and 60-year-old women1. This indicates a general stability in hemoglobin levels across different age groups, with a slight increase in older women.
Iron Deficiency and Iron Overload
Iron Deficiency
Iron deficiency is a common issue among women, particularly those of reproductive age. The World Health Organization (WHO) defines iron deficiency as serum ferritin levels below 15 µg/L. In the Danish study, 17.2% of 30- and 40-year-old women had serum ferritin levels below this threshold, indicating depleted iron stores1. Another study found that healthy women with normal menses lose about 1 mg of iron per menstrual cycle, while those with menorrhagia (excessive menstrual blood loss) lose significantly more, averaging 5.2 mg per cycle6. This substantial loss can lead to iron-deficient anemia if not managed properly.
Iron Overload
Iron overload, defined as serum ferritin levels above 150 µg/L, becomes more prevalent with age and higher body mass index (BMI). A study involving 4625 women aged 40 to 70 years found that 4.65% had iron overload, with the median serum ferritin concentration nearly doubling from the 45-50 age group to the 65-70 age group10. This suggests that older and obese women are at a higher risk of accumulating excessive iron.
Recommended Daily Iron Intake
Variations in Recommendations
The recommended daily allowance (RDA) for iron varies by country and physiological status. In the United Kingdom, the RDA for menstruating women is 14.8 mg, while it is 18 mg in the United States2. For non-menstruating women, the RDA is lower, at 8.7 mg in the UK and 8 mg in the US2. These recommendations aim to balance iron intake with the body's needs, considering factors like menstrual blood loss and overall health.
Iron Requirements in Menstruating Women
Menstruating women have higher iron requirements due to blood loss during menstruation. Studies have calculated that adult menstruating women need about 2.84 mg of absorbed iron per day, translating to a dietary requirement of approximately 18.9 mg per day when considering an average iron bioavailability of 15% in a Western diet4. This highlights the importance of adequate dietary iron intake to prevent deficiency.
Conclusion
Normal iron levels in women vary significantly with age, menstrual status, and overall health. Younger women, particularly those with heavy menstrual bleeding, are more prone to iron deficiency, while older women and those with higher BMI are at risk of iron overload. Understanding these variations is crucial for tailoring dietary recommendations and managing iron-related health issues effectively.
Sources and full results
Most relevant research papers on this topic
Iron stores in 1359, 30- to 60-year-old Danish women: Evaluation by serum ferritin and hemoglobin
Serum ferritin levels increase in 50-year-old women and remain stable in 60-year-old women, with iron deficiency anemia occurring in 2.3% of 30- and 40-year-old women and 1.1% of 50- and 60-year-old women.
Observational StudySerum Iron and Hemoglobin Values of 275 Healthy Women.∗
Serum iron levels decrease with age in healthy women, but this decrease is not accompanied by a decrease in hemoglobin values or a correlation with menopause status.
Observational StudyIron requirements in menstruating women.
New iron requirements for adult women and teen-agers have been increased to 2.84 mg/d and 3.21 mg/d, respectively, with optimal bioavailability in a Western-type diet at 15%.
Observational Study
Highly CitedPhysiologically based serum ferritin thresholds for iron deficiency in women of reproductive age who are blood donors
A higher ferritin threshold of 25 g/L is needed for iron deficiency in female blood donors aged 20 to 49 years, compared to the WHO guideline of 15 g/L for healthy women.
Observational StudyIron-dependent erythropoiesis in women with excessive menstrual blood losses and women with normal menses
Women with excessive menstrual blood losses (menorrhagia) lose five-to-six times more iron than healthy women with normal menses, potentially increasing their risk of developing iron-deficient anemia.
Observational Study
Rigorous JournalSerum Ferritin in the Evaluation of Iron Status in Young Healthy Women
Serum ferritin levels are highly correlated with bone marrow iron stores, with iron stores absent or scanty in about 70% of healthy young women.
Observational StudyBody iron excretion by healthy men and women.
Direct iron excretion measurements in healthy men and women confirm the wide range of iron requirements in humans, with menstrual iron accounting for 90% of the variation.
Observational Study
Very Rigorous JournalHighly CitedFerritin in the Serum of Normal Subjects and Patients with Iron Deficiency and Iron Overload
Ferritin levels in serum are a quantitative measure of storage iron in normal subjects and those with iron deficiency or overload.
Highly CitedIron Storage in Women is Positively Correlated with Aging and BMI Values
Serum ferritin levels in middle-aged women are positively correlated with age and BMI, suggesting an increasing prevalence of iron overload with age and BMI.
Observational Study