title: Low Diagnostic Utility of Rechecking Hemoglobins Within 24 Hours in Hospitalized Patients.
abstract: BACKGROUND
  Clinicians often repeat hemoglobin tests within a 24 hour period to detect or monitor anemia. We sought to determine the percentage of hemoglobin tests repeated within a single hospital day that were at least 1.0 g/dL lower than the first test.
  
  
  METHODS
  We performed a retrospective cross-sectional analysis of hospitalized adults on medical or surgical services over 1 year at a single academic hospital. Using patient and laboratory data in the electronic health record, we analyzed the proportion of repeated hemoglobin test results that were at least 1 g/dL less than the initial hemoglobin value of that day, excluding days when transfusions were administered.
  
  
  RESULTS
  A total of 88,722 hemoglobin tests were obtained from 12,877 unique patients, who contributed a total of 86,859 hospitalization days. In 12,230 (14.1%) of those days, 2 or more hemoglobin tests were obtained within a single day. In the 6969 days with 2 hemoglobin tests obtained and no transfusions given, 949 (13.5%) were ≥1 g/dL lower than the initial hemoglobin value of that day, and 260 (3.7%) were ≥2 g/dL lower. Repeated tests did not often reach transfusion thresholds: 482 (6.9%) of repeat hemoglobin values were <8 g/dL, and 64 (0.9%) were <7 g/dL.
  
  
  CONCLUSIONS
  Hemoglobin tests were repeated in 14% of hospital days. For patients who had 2 hemoglobin tests obtained on the same day, 13.5% demonstrated a clinically significant drop. This information may be helpful to clinicians when considering whether repeat testing is appropriate.
authors.affiliation: Division of Hospital Medicine, Department of Medicine, University of California, San Francisco. Electronic address: Alvin.rajkomar@ucsf.edu.
authors.forename: Alvin
authors.initials: A
authors.lastname: Rajkomar
authors.affiliation: Department of Epidemiology and Biostatistics, University of California, San Francisco.
authors.forename: Charles E
authors.initials: CE
authors.lastname: McCulloch
authors.affiliation: Division of Hospital Medicine, Department of Medicine, University of California, San Francisco.
authors.forename: Margaret C
authors.initials: MC
authors.lastname: Fang
mesh_terms: D000368:Aged; D000740:Anemia / Q000175:diagnosis / Q000378:metabolism* / Q000628:therapy; D003430:Cross-Sectional Studies; D017707:Erythrocyte Transfusion; D005260:Female; D006454:Hemoglobins / Q000378:metabolism*; D006760:Hospitalization; D006801:Humans; D008297:Male; D000069342:Medical Overuse; D008875:Middle Aged; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D006454:Hemoglobins
keywords: Anemia; High-value care; Laboratory testing; Overuse