What you can do to optimize blood conservation in ObGyn practice

Iron deficiency lies at the root of most cases of anemia

Iron deficiency affects an estimated 2.15 billion people globally, with a prevalence of 12% to 43% worldwide.^3,4 The daily iron requirement is 1 mg of elemental iron for nonobstetric patients, 2 mg for pregnant and lactating women. Latent iron deficiency is common in women who have had multiple pregnancies. These and other important facts about iron are described in the Box “Essential facts about iron”.

In iron-deficiency anemia, the following serum levels are reduced:

• Iron. A normal reading is 60 to 170 μg/dL.
• Hemoglobin, a measure of the production and turnover of red blood cells. A normal level is ≥12 g/dL (≥11 g/dL in pregnancy).
• Serum ferritin (a protein that stores iron). A normal reading is 12 to 150 ng/mL.
• Transferrin saturation. Transferrin is a transporting protein that shuttles iron to the bone marrow. The normal transferrin saturation level ranges from 20% to 50%.

Ferritin and hemoglobin levels tend to be the most efficient indicators of iron status.⁵

Some clinicians may also use:

• Mean corpuscular volume (MCV). Normal is 80 to 96 fL.
• Random distribution of red blood cell weight (RDW). A normal value is 11.5% to 15.5%.
• Reticulocyte count. Normal is 0.4% to 2.3%.

Laboratory tests for iron deficiency

When the Blood Conservation Program is initially consulted, the laboratory studies we recommend are based on the clinical presentation and condition of the patient. During pregnancy, we try to take account of the normal hemodynamic changes that occur during gestation. Therefore, we recommend:

• assessment of the serum ferritin level
• complete blood count (CBC) with differential. (If the hemoglobin/hematocrit is low, a peripheral smear is recommended to further evaluate microcytic anemia.)

Transferrin saturation and serum iron levels have not been shown to be useful markers in pregnant women because they are not specific for iron-restricted erythropoiesis and can be abnormally low during pregnancy.⁶

In nonpregnant patients, we recommend initial evaluation of:

• serum iron level
• total iron-binding capacity (TIBC). Normal levels are 240 to 450 μg/dL
• transferrin saturation.

A caveat about the ferritin level

Ferritin is both an iron-storage indicator and an acute-phase protein, so the clinician must be careful to exclude inflammatory processes that can elevate the ferritin level, giving a false indicator of iron stability in the maternal system. These inflammatory processes can include preeclampsia and neoplastic or infectious conditions.⁷ Transferrin saturation, however, is not affected by inflammatory processes and can be used as a confirmatory test for iron deficiency.⁴

Try oral iron supplementation first

When laboratory testing confirms the presence of iron-deficiency anemia, initial management is oral iron supplementation for 2 weeks, followed by repeat laboratory evaluation.

For patients scheduled for surgery, oral therapy includes a daily dosage of:

• 325 mg of ferrous sulfate
• 250 mg of vitamin C
• 800 μg of folic acid
• a multivitamin.

For perinatal patients, the daily oral regimen is:

• 325 mg of ferrous sulfate
• 250 mg of vitamin C
• a prenatal vitamin.

These medications are the least expensive alternatives for treating anemia.

Advise patients who are taking iron supplements not to ingest the medication with dairy products, coffee, tea, or foods that have a high content of phytic acid (e.g., grains, seeds, and legumes). Foods and prescription drugs that interact with iron supplements are listed in TABLE 1, along with recommendations on optimal timing of iron supplementation and other medications.

When you prescribe oral iron supplementation, bear in mind that some patients experience gastrointestinal side effects—constipation, nausea, diarrhea—so unpleasant that they stop taking their medication. In that scenario, you will need to find alternative formulations or delivery routes. One alternative you can suggest is a daily helping of blackstrap molasses, which supplies 27 mg of elemental iron per tablespoon.

Oral therapy should be continued even after hemoglobin and ferritin levels normalize. If laboratory values remain low after 2 weeks of oral therapy, parenteral therapy can be added to the oral regimen.

Therapy may be discontinued 2 months after delivery of the infant or surgery as long as the cause of the blood loss has been remedied. If the mother is breastfeeding, she should continue taking a prenatal vitamin until nursing has stopped.

TABLE 1

Some foods and drugs don’t mix well with iron