CBC Levels Affected by a Woman's Menstrual Period

Impact on Red Blood Cell Parameters and Iron Stores

Hemoglobin and hematocrit levels are the primary CBC parameters affected by menstrual blood loss, with women experiencing iron loss averaging 0.3-0.5 mg/day during menstruation, which can lead to decreased values compared to non-menstruating periods, according to the American Journal of Kidney Diseases 1
Hormonal contraceptive use reduces menstrual blood loss and consequently leads to higher serum iron levels and better maintenance of hemoglobin levels, as reported by the American Journal of Kidney Diseases 1

For accurate interpretation of CBC results, clinicians should consider timing within the menstrual cycle, especially when evaluating for anemia in women with heavy periods, as suggested by the American Journal of Kidney Diseases and Gut 1, 2
Not accounting for menstrual cycle phase when interpreting borderline low hemoglobin or ferritin values in women of reproductive age is a common pitfall, according to the American Journal of Kidney Diseases 1