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Iron Deficiency
Nancy Collins, PhD, RD, LD/N, FAPWCA
atients often complain about fatigue and tiredness. Some
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might even say, “Maybe I am low on iron.” What they are
suggesting is the presence of iron deficiency anemia, which
Table 1. Symptoms of iron deficiency
Pale skin color (pallor)
Fatigue
Irritability
Weakness
Shortness of breath
Sore tongue
Brittle nails
Unusual food cravings (pica)
Decreased appetite
Headache — frontal
Blue tinge to sclerae (whites of eyes)
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occurs when iron is sufficiently deficient to diminish erythropoiesis and cause the development of anemia. This may, in
fact, be the source of the problem because iron is the nutrient
most commonly deficient — approximately 40% of the total
world population is affected.1 Because there are many other
types of anemia — eg, pernicious anemia, anemia of chronic
disease, hemolytic anemia, and megaloblastic anemia — it is
important to be able to distinguish one type from another.
Treatment interventions may vary depending on the type of
anemia and the source of the problem. In this article, we take
a closer look at iron deficiency anemia.
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Note: There may be no symptoms if anemia is mild.
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Functions of Iron
Iron is the fourth most abundant element in the earth’s
crust yet it is only a trace element in the human body. Although iron makes up only 0.0004% of the human body’s
mass, it is an essential component or cofactor of numerous
metabolic reactions.2 Iron has many functions in the body —
perhaps the most important as a component of a protein
called heme. Iron is necessary to manufacture hemoglobin, the
protein in red blood cells that carries oxygen from the lungs
to the body’s tissues and what gives blood its usual red color.
Iron also plays a role in immune function, cognitive status,
and many other processes including the synthesis of DNA, collagen, and bile acids.
iron deficiency. It is important to note that in mild cases of
deficiency, no symptoms may be present.
Diagnosing Iron Deficiency Anemia
The first step in any diagnosis is a thorough history and
physical. The clinician should ask about blood loss, medications such as extended NSAID use, family history of anemia, any fatigue-related lifestyle changes, and dietary and
supplement intake. If anemia is suspected, the physical
exam should note any splenomegaly, blood in the stool,
pallor, and other physical symptoms as listed in Table 1. A
complete blood count (CBC) should be performed. The
laboratory diagnosis of iron deficiency anemia includes:
• Low hemoglobin (Hgb) and hematocrit (Hct)
• Small red blood cells (microcytic cells)
• Low serum ferritin
• Low serum iron
• High iron-binding capacity (TIBC)
• Blood in the stool (visible or microcytic).
Many practitioners only assess Hgb and Hct, but it is
important to remember that iron deficiency occurs in
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Iron Deficiency
The term anemia is used to describe many conditions
where red blood cells are not providing adequate oxygen to
body tissues. The most common type and cause of anemia is
iron deficiency anemia — ie, a decrease in the number of red
cells in the blood caused by too little iron. In other words,
when too little iron is available to produce an adequate
amount of hemoglobin, anemia results. Iron deficiency anemia has many causes, including too little iron in the diet, poor
iron absorption, and iron depleted by blood loss due to gastrointestinal bleeding related to ulcers, heavy menstrual
bleeding, and certain types of cancers, particularly in the
stomach, colon, or esophagus. Table 1 lists the symptoms of
Adapted from Medline Plus Medical Encyclopedia. Available at:
www.nlm.nih.gov/medlineplus/ency/article/000584.htm. Accessed March
1, 2011.
Nancy Collins, PhD, RD, LD/N, FAPWCA, is founder and executive director of RD411.com and Wounds411.com. For the past 20 years, she has served as a consultant to healthcare institutions and as a medico-legal expert to law firms involved in healthcare litigation. Correspondence may be sent to Dr. Collins at
[email protected]. This article was not subject to the Ostomy Wound Management peer-review process.
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Table 2. Recommended dietary allowances for iron for infants (7 to 12 months), children, and adults
Age
Males
(mg/day)
11
7
10
8
11
8
8
Pregnancy
(mg/day)
N/A
N/A
N/A
N/A
27
27
N/A
Lactation
(mg/day)
N/A
N/A
N/A
N/A
10
9
N/A
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7 to 12 months
1 to 3 years
4 to 8 years
9 to 13 years
14 to 18 years
19 to 50 years
51+ years
Females
(mg/day)
11
7
10
8
15
18
8
Source: Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium and Zinc. Washington, DC: National Academy Press;2001.
meal consumption and are not eating foods high in iron.
These foods include liver, eggs, kidney, beef, dried fruits,
enriched whole grain cereals, enriched flour, lentils, molasses, and oysters. To compound the problem, many of
these foods are not typically found on healthcare menus.
For practical purposes, the best food choices for iron are
enriched products and meats. Fortified ready-to-eat cereals
usually contain at least 25% of the US recommended daily
allowance (RDA) for iron. Table 2 outlines the iron requirements for various age groups.
Iron is found in the diet in two forms — heme iron,
which is well absorbed, and non-heme iron, which is poorly
absorbed. Vitamin C enhances the absorption of non-heme
iron from the intestine, so it may be helpful to combine
foods with iron and vitamin C to increase the amount of
iron absorbed. For example, a recommended nutritional intervention is to serve orange juice with meals to increase absorption of non-heme iron. Citrus fruits are well-known for
their vitamin C content; many vegetables such as tomatoes,
cauliflower, broccoli, and potatoes are also a good source of
vitamin C and can be utilized to increase absorption.
Iron supplements. The issue of iron supplementation
should be approached cautiously. Many patients take a
daily multivitamin, which typically contains 18 mg of iron.
Additional iron supplements should be prescribed only if
the anemia has been conclusively defined as iron deficiency.
A serum ferritin level <15 micrograms per liter confirms
iron deficiency anemia in women and suggests a possible
need for iron supplementation. 4 For adults who are not
pregnant, the Centers for Disease Control (CDC) recommends taking 50 mg to 60 mg of oral elemental iron (the
approximate amount of elemental iron in one 300-mg
tablet of ferrous sulfate) twice daily for 3 months for the
therapeutic treatment of iron deficiency anemia.5 However,
physicians should evaluate each person individually and
prescribe according to individual needs.
Iron supplements may cause side effects such as constipation, black stools, diarrhea, nausea, and leg cramps.
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stages and Hgb and Hct may remain normal until well into
the cycle of iron depletion. In the early stage, iron stores
are depleted and ferritin levels are decreased. Hgb and Hct
may still be normal in this stage. As the depletion of iron
progresses, transferrin levels rise and serum iron levels fall.
If the depletion continues over time, normocytic, normochromic anemia occurs. The final stage is the development of microcytic, hypochromic anemia.
The degree of decrease in Hgb and Hct depends on the
length of time the bone marrow has been without sufficient
supplies of iron. Other indicators on the CBC also should
be reviewed, including mean corpuscular volume (MCV),
mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC). The MCV
measures the mean or average size of individual red blood
cells. In iron deficiency, the MCV is low, indicating the cells
are microcytic.3 The MCH measures the amount of hemoglobin present in one red blood cell. The MCHC measures
the proportion of each cell taken up by hemoglobin 3; results are reported in percentages, reflecting the proportion
of hemoglobin in the red blood cells. The MCV, MCH, and
MCHC all are decreased in iron deficiency anemia. MCHC
is the last to be affected. This is due to the fact that as the
marrow becomes more and more depleted of iron, it produces smaller cells with a smaller amount of hemoglobin
in each cell in an attempt to keep the concentration of hemoglobin normal.3 A growing body of evidence supports
using serum ferritin as an initial indicator of iron deficiency. If iron deficiency is suspected, it may be worthwhile
to request a serum ferritin level to supplement the CBC.
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Treatment
Iron deficiency treatment is dependent on the cause. For
example, if the cause is blood loss, the source of blood loss
must be identified and corrected. In many elderly and patients residing in long-term care facilities, the cause of anemia often involves poor food intake and poor absorption.
Many institutionalized patients have less-than-optimal
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Many patients may find iron very difficult to tolerate. Enteric coated supplements may be easier to tolerate but they are not recommended because
they may not be adequately absorbed.6 Liquid iron tends to stain the teeth
so it is best to mix it with juice and use a straw.
Many brands and forms of iron supplements, including ferrous and ferric, are available today, and one type may agree with a patient better than
another. Ferrous iron salts (ferrous fumarate, ferrous sulfate, and ferrous
gluconate) are the best absorbed forms of iron supplements.6 Advising the
patient to take iron supplements with meals may help with any gastrointestinal issues. Other tips are to begin with a half-dose and build up to the
full dose and to take iron in divided doses throughout the day. If a deficiency
cannot be corrected with oral supplements due to tolerance or other problems, a variety of intravenous iron preparations are available.
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Practice Points
In wound healing, collagen synthesis requires the hydroxylation of lysine
and proline, which utilize several cofactors, including ferrous iron and vitamin C. Impaired wound healing results from deficiencies of any of these
cofactors.7 Treating iron deficiency anemia takes a team approach; each discipline has something to offer. The nursing staff may be the first to identify
low levels of Hgb and Hct on the lab reports and notify the physician. The
physician may order additional tests, multivitamins, or supplements. The
registered dietitian (RD) should monitor oral intake and recommend appropriate food choices and tips such as using vitamin C to increase absorption. The pharmacist should monitor for any food or drug interactions and
can suggest different brand and forms of iron if tolerance problems occur.
It is a myth that anemia is a normal part of aging and is simply something
to expect and accept. With a little attention and knowledge, we can keep
pumping the iron. ■
References
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1. Escott-Stump S. Nutrition and Diagnosis-Related Care, 5th ed. Philadelphia, PA: Lippincott, Williams, & Wilkins;2002:472.
2. Uthman E. Nutritional Anemias. Available at: http://web2.iadfw.net/uthman/nutritional_anemia/nutritional_anemia.html. Accessed March 7, 2011.
3. Kennedy R. The Doctor’s Medical Library. Red Blood Cells. Available at: www.medical-library.net/cbc_red_blood_cells.html. Accessed March 7, 2011.
4. Recommendations to prevent and control iron deficiency in the United States. Centers for
Disease Control and Prevention. MMWR Recomm Rep. 1998;47(RR-3):1–29.
5. National Institutes of Health. Office of Dietary Supplements. Dietary Fact Sheet: Iron. Available at http://ods.od.nih.gov/factsheets/iron. Accessed March 7, 2011.
6. Brittenham GM.Disorders of iron metabolism: iron deficiency and overload. In: Hoffman
R, Furie B, Benz EJ Jr, et al. Hematology: Basic Principles and Practice, 3rd ed. New York,
NY: Churchill Livingstone, Harcourt Brace & Co;2000.
7. Campos AC, Groth AK, Branco AB. Assessment and nutritional aspects of wound healing.
Curr Opin Clin Nutr Metabol Care. 2008;11(3):281–288.
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Coming next month:
urinary tract infections and cranberry research
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