Incidence and diagnosis of iron deficiency among patients receiving a blood transfusion in the emergency department

Abstract Background Iron deficiency anemia (IDA) is the most common nutritional disorder worldwide and a leading cause of anemia in the United States. Anemia accounts for over 800,000 Emergency department (ED) visits annually in the United States, many of which are for blood transfusions. Despite its burden, IDA remains underdiagnosed and undertreated. This study sought to characterize the incidence of iron deficiency in patients receiving a blood transfusion in the ED at a large academic medical center and to identify areas for improvement in diagnosis management.Methods We conducted a retrospective cohort study of adult patients with severe anemia who received at least one PRBC transfusion in our ED between January 1stand December 31st, 2021. Patients considered at risk for iron deficiency included those with a mean corpuscular volume (MCV) < 80 fL on the day of the ED visit, a ferritin < 40 ng/mL on the day of or with any recorded value prior to the ED visit, or an iron saturation < 20% on the day of or with any recorded value prior to the ED visit. Patients with confirmed iron deficiency included those with ferritin levels < 40 ng/mL or iron saturation < 20% within 90 days prior to the ED visit. This 90-day period included labs checked on the day of the ED visit. We also collected B12 and folate levels to determine the incidence of B12 deficiency and folate deficiency, respectively, within 90 days prior to the ED visit. We defined B12 deficiency and those at risk for B12 deficiency as those with a B12 level < 200 ng/L or with a B12 level 200-399 ng/L, respectively. We defined folate deficiency as having a folate level < 4 mcg/L.Results: Four hundred and sixty-two patients accounted for 558 ED encounters for severe anemia requiring at least one PRBC transfusion. The median age of the cohort was 68 years. Within this cohort, we identified 210 (45%) patients at risk of iron deficiency and 136 (29%) patients with confirmed iron deficiency based on ferritin or iron saturation levels within 90 days of the ED visit. Among these patients with iron deficiency, 44/136 (32.5%) presented with an MCV < 80 fL, 88/136 (65%) presented with an MCV 80-100 fL, and 10/136 (7.5%) presented with an MCV > 100 fL. These findings show that iron deficiency does not always present with microcytosis. Fifteen (3%) of 462 patients had B12 deficiency and another 38/462 (8%) were at risk for B12 deficiency based on levels within 90 days of the ED visit. Two patients had folate deficiency based on levels within 90 days of the ED visit.Conclusions This study highlights the high prevalence of iron deficiency in patients presenting to the ED at a large academic medical center. Furthermore, relying on a low MCV level alone may lead to underdiagnosis of iron deficiency, underscoring the importance for a comprehensive assessment of iron stores when working up a patient with severe anemia. This study also suggests the need for further research to determine whether early identification and treatment of iron deficiency can reduce the frequency of ED visits for blood transfusions, decrease the number of PRBC units transfused, lower hospital admission rates, improve patient outcomes and reduce healthcare cost in our patient population.