From the Guidelines
During menstruation, hemoglobin (Hgb) typically drops by approximately 0.5-1.0 g/dL in women with normal menstrual flow, as supported by general medical knowledge and studies on iron deficiency and anemia 1. This decrease is generally not clinically significant for most healthy women. However, women with heavier menstrual bleeding (menorrhagia) may experience more substantial drops of 1-2 g/dL or more. The average blood loss during a normal menstrual period is about 30-40 mL, which contains roughly 15-20 mg of iron, as noted in a study on iron deficiency prevention 1. The body can usually compensate for this loss through increased iron absorption and mobilization of iron stores. Women with consistently heavy periods may develop iron deficiency anemia over time if their dietary iron intake doesn't meet their increased needs. Those experiencing symptoms of anemia (fatigue, weakness, shortness of breath) during menses should consider iron supplementation (typically 325 mg ferrous sulfate daily) and consult with their healthcare provider, especially if menstrual bleeding seems excessive or if symptoms persist between periods. It's essential to note that the definition of anemia and its severity can vary, with the World Health Organization defining anemia based on hemoglobin concentrations, as mentioned in a study on iron deficiency in female athletes 1. In clinical practice, the target hemoglobin range for therapy can vary, but generally, a range of 11-12 g/dL is considered suitable for most patients, as recommended in guidelines for anemia in chronic kidney disease 1. Ultimately, the management of anemia and iron deficiency during menstruation should be individualized, taking into account the woman's overall health, dietary habits, and severity of menstrual bleeding.
From the Research
Hemoglobin Drop During Menses
- The amount of hemoglobin (Hgb) drop during menses is not directly stated in the provided studies, but we can look at the effects of heavy menstrual bleeding on Hgb levels.
- A study published in 2012 2 found that women with heavy menstrual bleeding who received tranexamic acid therapy had significant increases in mean serum Hgb levels, with a mean increase of ≥0.71 g/dL after the third cycle.
- Another study published in 2015 3 reported that women with severe anemia due to heavy menstrual bleeding had a mean nadir Hgb level of 4.15 g/dL, indicating a significant drop in Hgb levels.
- However, these studies do not provide a direct answer to the question of how much Hgb typically drops during menses.
Factors Affecting Hemoglobin Levels
- Heavy menstrual bleeding is a common cause of iron deficiency anemia in women, which can lead to a drop in Hgb levels 2, 3.
- The use of iron supplements, such as ferrous sulfate, can help increase Hgb levels in individuals with iron deficiency anemia 4, 5, 6.
- The bioavailability and side effects of different iron supplements can vary, with ferrous bisglycinate being a novel amino acid iron chelate that may be more bioavailable and associated with fewer gastrointestinal adverse events 6.
Hemoglobin Levels in Different Populations
- A systematic review and meta-analysis published in 2023 6 found that ferrous bisglycinate supplementation resulted in higher Hgb concentrations in pregnant women compared to other iron supplements.
- However, no significant differences in Hgb concentrations were detected among children supplemented with ferrous bisglycinate compared to other iron supplements 6.