| Journal of Hematology, ISSN 1927-1212 print, 1927-1220 online, Open Access |
| Article copyright, the authors; Journal compilation copyright, J Hematol and Elmer Press Inc |
| Journal website http://www.thejh.org |
Letter to the Editor
Volume 8, Number 2, June 2019, pages 86-87
A Quantitative Approach to Dilutional Anemia
Table
| Step 1: Calculate initial total blood volume |
| Various calculations exist to estimate total blood volume in normal human subjects, without a clear gold standard. The simplest may be an estimation that blood volume equals 65 mL/kg of total body weight in women and 75 mL/kg in men [9-11]. |
| Case: A 60-kg woman would be expected to have 60 kg × 65 mL/kg = 3,900 mL or 39 dL of total blood volume. |
| Step 2: Calculate total body hemoglobin |
| This is the provided hemoglobin concentration in g/dL multiplied by the total blood volume in dL |
| Case: Total body hemoglobin = 12 g/dL × 39 dL = 468 g hemoglobin |
| Step 3: Calculate expected post intravenous fluid bolus total blood volume |
| For every 1 L of normal saline, approximately one-fourth will stay in the intravascular space. For D5W, only one-twelfth will remain [12]. |
| Case: 1) 4 L infusion of normal saline × 1/4 = 1.0 L increased intravascular volume; 2) New total intravascular volume = initial blood volume + intravascular volume from the infusion = 3.9 L + 1.0 L = 4.9 L or 49 dL |
| Step 4: Calculate the expected post-infusion hemoglobin concentration |
| Case: Expected post-infusion hemoglobin concentration = 468 g total body hemoglobin divided by 49 dL total blood volume = 9.6 g/dL |