Utility of Ferritin at Registration as a Screen for Development of Anemia in Third Trimester [ID: 1362276

Abstract

INTRODUCTION: The objective of this study was to assess the utility of screening ferritin (<20 weeks of gestation) in pregnant patients on hemoglobin (Hgb) and hematocrit (Hct) later in gestation. METHODS: Pregnant patients who received nondiagnostic ferritin labs at less than 20 weeks of gestation from 2019 to 2021 were retrospectively identified. Patients were excluded if ferritin testing was conducted for diagnostic purposes or if the patient had a history of anemia. Labs at the time of registration, 28 weeks of gestation, and at delivery were analyzed. Anemia was defined as Hgb less than 11 g/dL. This study was approved by the University of Washington IRB, and patient consent was waived. RESULTS: Forty-four patients underwent routine ferritin screening at registration, with ferritin levels ranging from 10 to 136 ng/mL (average 52.5 ng/mL). Average Hgb/Hct at registration were 12.6 g/dL and 37.3%, respectively. At 28 weeks of gestation, Hgb/Hct were obtained on 42 patients, of whom 9 patients were diagnosed with anemia. Patients diagnosed with anemia had a screening ferritin level of 33.6 ng/mL, and nonanemic patients had a ferritin level of 57.4 ng/mL (P=.1). When a cutoff of 50 ng/mL was studied to compare patients with “low” versus “normal” ferritin, ferritin less than or equal to 50 ng/mL had significantly lower Hgb levels at 28 weeks compared to those with ferritin greater than 50 ng/mL (P=.013). On labor and delivery (L&D), Hgb/Hct was obtained on 44 patients, and 14 were diagnosed with anemia. Anemic patients on L&D had significantly lower screening ferritin compared to nonanemic, 31.9 and 62.2 ng/mL, respectively (P=.016). CONCLUSION: Ferritin screening in early pregnancy may help predict lower Hgb in later gestation. Using a higher ferritin cutoff of 50 ng/mL in early pregnancy for identifying patients at risk for anemia in the third trimester may be warranted. Larger prospective studies are needed to evaluate further the utility of ferritin screening.