A 68 y/o female patient presenting with moderate fatigue along with other non-specific symptoms. Upon closer physical examination, she shows 'spooning' of the nails and some mild stomatitis. She is subsequently diagnosed with iron deficiency anemia, most likely due to poor dietary intake of iron. Her serum ferritin is 8 g/L. She has been "scoped" from above and below with no evidence of active bleeding. Her peripheral smear shows a microcytic, hypochromic anemia consistent with iron deficiency. The student wants to replete this patient with oral ferrous sulfate 325mg po TID but the patient states she's had significant GI problems with oral iron in the past. 

What other options do you have?

Even if the patient could tolerate oral iron, iron is poorly absorbed orally. Iron is absorbed from foods. It is absorbed better from protein sources such as meat, eggs, etc than grains, vegetables, etc. An acidic
environment promotes better absorption. Often oral iron is given with ascorbic acid (vitamin C) to promote absorption. Concomitant citrus juice aids absorption as well.

Given our young lady's past history with oral iron, parenteral iron is probably our best bet. Parenteral iron can be given intramuscularly or intravenously. When given intramuscularly, iron dextran can permanently
stain the skin. To avoid this side effect, a Z-track technique is utilized. A max of 2 to maybe 5 ml can be injected IM, depending on the patient. Large IM injections can be painful.

Most people when presented with a patient who needs iron repletion or is intolerant to oral iron preparations will choose iron dextran as a total dose intravenous infusion. Although not FDA approved, this method has been used often and is efficacious and convenient.

Calculate the total iron dextran dose (see equation below). Dilute this total volume of iron dextran in 0.9% sodium chloride (when mixed with D5W there's a greater risk of phlebitis). Give a "test dose" of 1-5 ml of the IV solution and observe the patient for 10-30 minutes. If no reaction, continue the infusion. Infuse total volume over 4-6 hours. The recommended max infusion rate is no more than 50 mg of elemental iron per minute. Each 1 ml of iron dextran contains 50 mg of elemental iron. 

Possible side effects include: anaphylaxis (rare), arthralgias, pain at injection site, fever, etc. Allergic type reactions can be treated with a combination of diphenhydramine, corticosteroids, and/or epinephrine, etc.

To figure a total dose of iron dextran, use the following equation:

*    Adults and children over 15 kilograms:
*               DOSE (mL) = 0.0442 (desired Hb - observed Hb)
*                           x LBW + (0.26 x LBW)
*               mL = milliliter
*               Hb = hemoglobin in g/dL
               LBW = lean body weight in kilograms

Important note - make sure the patient is replete with all other nutrients and vitamins necessary for hemtopoiesis (folate, vitamin B-12, etc).

Other injectable options include sodium ferric gluconate complex and iron sucrose. I have no experience with these two newer products.

From MICROmedex:

The overall consensus regarding the intravenous administration of iron dextran is that TDI (total dose infusion) is the preferred method (Kumpf, 1996; Auerbach et al, 1988; Benito & Guerrero, 1973; Varde, 1964; Halpin, 1982). TDI appears to be safe, efficacious, convenient, and requires less time for administration and preparation than multiple intravenous bolus injections, and is therefore more cost-effective (Kumpf & Holland, 1990). However, phlebitis may occur with continuous infusions in general, and the intravenous bolus injection may be an acceptable alternative in this situation (Gever, 1980).

A 30-year-old male tolerated the administration of iron dextran when added to TPN (total parenteral nutrition) solution but experienced allergic symptoms when iron dextran was administered by intravenous bolus injection (Porter et al, 1988). The patient was able to tolerate iron dextran up to 10 milligrams/day administered in TPN solution; however, a supplemental dose of iron dextran 25 milligrams in D5W (5% dextrose in water) 100 mL as a test dose, followed by an iron dextran 50 milligrams/dextrose 5% in water 500 mL infusion produced an allergic reaction characteristic of severe backache, extremity pain, and the onset of a vascular type headache within minutes of the infusion. Discontinuation of the iron dextran infusion and subsequent reinstatement of iron dextran 2 milligrams/day in TPN solution did not produce further allergic symptoms.

The authors concluded that iron dextran administered in TPN solutions may provide a safer method for intravenous iron infusion than other alternative routes of administration due to the long administration times associated with TPN infusions.

CONCLUSION:

Most authors regard TDI (total dose infusion) of iron dextran as the preferred method for intravenous administration. TDI appears to be safe, efficacious, convenient, and requires less time for administration and preparation than multiple intravenous bolus injections.

REFERENCES:

1. Auerbach M, Witt D, Toler W et al: Clinical use of the total dose intravenous infusion of iron dextran. J Lab Clin Med 1988; 111:566-570.
2. Benito RP & Guerrero TC: Response to a single intravenous dose versus multiple intramuscular administration of iron-dextran complex: a comparative study. Curr Ther Res 1973; 15:373-382.
3. Gever LN: Parenteral iron supplements. Nursing 1980; 10:60.
4. Halpin TC, Bertino JS, Rothstein FC et al: Iron-deficiency anemia in childhood inflammatory bowel disease: treatment with intravenous iron-dextran. JPEN 1982; 6:9-11.
5. Kumpf VJ: Parenteral iron supplementation. Nutr Clin Prac 1996; 11:139-146.
6. Kumpf VJ & Holland EG: Parenteral iron dextran therapy. DICP 1990; 24:162-166.
7. Porter KA, Blackburn GL & Bistrian BR: Safety of iron dextran in total parenteral nutrition: a case report. J Am Coll Nutr 1988; 7:107-110.
8. Varde KN: Treatment of 300 cases of iron deficiency of pregnancy by total dose infusion of iron-dextran complex. J Obstet Gynaecol Br Commonw 1964; 71:919-922.