The amount of iron lost and the amount needed to replace it following a known blood loss can be calculated from the estimated volume of blood loss.
(1) normochromic, normocytic red blood cells contain 1 mg of elemental iron for each 1 mL of red blood cells.
(2) hemoglobin is approximately 0.34% iron by weight
mg of iron lost =
= (volume of blood loss in mL) * (hematocrit in percent) / 100
= (hemoglobin in g/dL) * (mL of blood loss) / 100 * 0.0034 * 1000
• mL blood loss divided by 100 converts the blood loss to deciliters.
• The 1000 is for conversion from grams to milligrams.
• The amount of iron in plasma is much lower than that associated with hemoglobin.
If iron dextran is used for replacement (iron content 50 mg/mL):
volume of iron dextran to administer in mL =
= (mg of iron to replace) / 50
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Purpose: To estimate the amount of iron lost from a blood loss and to determine a replacement dose of iron dextran.
Specialty: Hematology Oncology, Clinical Laboratory, Obstetrics & Gynecology, Pedatrics, Surgery, general, Gastroenterology
Objective: laboratory tests, dosage calculations, dosage adjustments