Diagnosis of Iron Deficiency Anemia in Pregnancy

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Diagnosis of Iron Deficiency Anemia (IDA) in Pregnancy Reviewed By Medical Advisory Board
	Terms: Mean corpuscular volume (MCV) Mean corpuscular hemoglobin (MCH) Mean corpuscular hemoglobin concentration (MCHC) Red blood cell distribution width (RDW) Transferrin Serum iron (FE) Total iron-binding capacity Percent transferrin saturation (TSAT) Ferritin

Signs and Symptoms of Iron Deficiency Anemia (IDA)[1-6]

Pale skin

An elevated platelet count

Inflamed tongue (glossitis)
Spoon nails
Blue sclerae
Weakness
Restless leg syndrome
Fatigue
Irritability
Pica -A craving for peculiar substances such as soil or clay or an abnormal appetite for foods such as cornstarch, tomatoes, lemons, and ice.

The U.S. Preventive Services Task Force (USPSTF) [7] and the Centers for Disease Control and Prevention (CDC) recommend routine screening for iron deficiency anemia in pregnant women [8]. During pregnancy the hemoglobin concentration declines during the first and second trimesters because of an increase in blood volume [9]. Therefore, it is recommended anemia criteria for the specific stage of pregnancy be used [8].

Trimester	Hemoglobin (g/dL)	Hematocrit (%)
First	<11	<33
Second	<10.5	<32
Third	<11	<33

For African-American adults, the Institute of Medicine recommends lowering the cutoff levels for Hgb and Hct by 0.8 g/dL and 2%, respectively (12).

In women who are otherwise healthy anemia may be treated by prescribing an oral dose of 60-120 mg/day of iron. Counsel pregnant women about correcting iron-deficiency anemia through diet.

If after 4 weeks the anemia does not respond to iron treatment (the woman remains anemic for her stage of pregnancy and Hb concentration does not increase by 1 g/dL or Hct by 3%) despite compliance with an iron supplementation regimen and the absence of acute illness, further evaluate the anemia by using other tests, including serum ferritin concentration, RDW, and MCV[8]

Ferritin is the storage form of iron in cells. Measurement of ferritin levels has the highest sensitivity and specificity for diagnosing iron deficiency in anemic patients (15,16,17).

Serum Ferrtin value Interpretation

<=45 ng per mL Probable iron deficiency

>= 100 Not likely to be iron deficiency.
Evaluate for other causes of anemia.

= 46 to 99 Obtain total iron-binding capacity ( TIBC) ,serum iron (FE), and transferrin saturation (TSAT)

If TIBC is increased, serum iron is decreased , and transferrin saturation is decreased then most likely iron deficiency.
Probable iron deficiency If TIBC is decreased, serum iron is increased , and transferrin saturation is increased then not likely to be iron deficiency.
Evaluate for other causes of anemia

Red blood cell distribution width (RDW)

The RDW is usually elevated early in iron deficiency [10], but may also occur with vitamin B₁₂ or folic acid deficiency [11]. However, vitamin B₁₂ or folic acid deficiency results in blood cells that are larger than normal (macrocytic anemia) whereas, iron deficiency leads to the production of small red blood cells with an MCV of less than 80 fL (microcytic anemia).

Mean corpuscular volume (MCV)

An MCV of less than 80 fL (microcytic anemia) is consistent with iron deficiency, but is not specific for iron deficiency. A low MCV may also be seen with beta thalassemia trait and α-thalassemia-1 trait, anemia of chronic disease , and acquired or hereditary sideroblastic anemia.

Anemia of chronic disease (ACD) is the second most common form of anemia, next to iron deficiency anemia. Although the red blood cells in ACD are usually normal sized (normocytic), the cells may sometimes be microcytic. In ACD the serum ferritin will be normal or increased and the the serum iron and TIBC will be low, because underlying long standing systemic inflammatory disease or malignancy causes an increase in the production of ferritin by macrophages (white blood cells) and suppresses the production of red blood cells by the bone marrow. Iron becomes trapped in the macrophages and is unavailable for hemoglobin synthesis.

In patients with thalassemia minor, the RDW is usually normal. The American College of Obstetricians and Gynecologists recommends that women of Southeast Asian or Mediterranean ancestry with a low MCV and normal iron status should be offered hemoglobin electrophoresis. All individuals of African descent should be offered hemoglobin electrophoresis regardless of their red blood cell indices.[13]

Acquired or hereditary sideroblastic anemia may also present with an elevated RDW and low MCV. However, serum iron and serum ferritin are increased in sideroblastic anemia, because red blood cells are unable to use available iron to make hemoglobin. Instead the iron accumulates in the red cell mitochondria producing sideroblasts.

Once the diagnosis of iron deficiency has been made the evaluation should continue to determine its cause.

REFERENCES

1.Brittenham GM.Disorders of iron metabolism: iron deficiency and overload.In: Hoffman R, Benz EJ Jr, Skikne B, et al, eds. Hematology: Basic Principles and Practice. 4th ed. New York, NY: Churchill Livingstone; 2004:481-487.

2. Sun ER, Chen CA, Ho G, Earley CJ, Allen RP. Iron and the restless legs syndrome. Sleep. 1998;21(4):371–377.

3. O’Keeffe ST, et al.. Iron status and restless legs syndrome in the elderly.Age Ageing. 1994;23(3):200–203.

4.Kettaneh A.,et al, Pica and food craving in patients with iron deficiency anemia: a case-control study in France.Am J Med 118.185-188.2005

5.&Mills M.E.Craving more than food: the implications of pica in pregnancy. Nurs Womens Health 11.: 266-273.2007

6. Kathula SK Am J Med - 01-JUL-2008;Craving Lemons: Another Form of Pica in Iron Deficiency

7. U.S. Preventive Services Task Force. Screening for Iron Deficiency Anemia—Including Iron Supplementation for Children and Pregnant Women: Recommendation Statement. Publication No. AHRQ 06-0589, May 2006. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/clinic/uspstf06/ironsc/ironrs.htm

8. Centers for Disease Control and Prevention. Recommendations to prevent and control iron deficiency in the United States.MMWR Recomm Rep.1998 47(RR-3):1>–29. http://www.cdc.gov/mmwr/preview/mmwrhtml/00051880.htm

9. Hytten FE, Paintin DB. Increase in plasma volume during normal pregnancy. J Obstet Gynaecol Br Commonw 1963;70:402-7.

10. Ginder GD. Microcytic and hypochromic anemias. In: Goldman L, Ausiello D, eds. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 163.

11.Dugdale M. Obstet Gynecol Clin North Am. 2001;28:363-381; Jacobs, DS, et al. Jacobs & DeMott Laboratory Test Handbook With Key Word Index. 5th ed. Cleveland, OH: Lexi-Comp, Inc; 2001.

12. Institute of Medicine (US). Iron deficiency anemia: recommended guidelines for the prevention, detection, and management among U.S. children and women of childbearing age. Washington, DC: National Academy Press; 1993.

13. Hemoglobinopathies in pregnancy. ACOG Practice Bulletin No. 78. American College of Obstetricians and Gynecologists. Obstet Gynecol 2007;109:229–37.

14. Helms RA, Herfindal ET, et al. Textbook of Therapeutics: Drug and Disease Management. Lippincott Williams & Wilkins, 2006. p 800

15. Killip S , et al., Iron deficiency anemia.Am Fam Physician. 2007 Mar 1;75(5):671-8. PMID:17375513

16. Ioannou GN, et al. ,Prospective evaluation of a clinical guideline for the diagnosis and management of iron deficiency anemia.Am J Med. 2002 Sep;113(4):281-7. PMID: 12361813

17. Ontario Association of Medical Laboratories. Guidelines for the use of serum tests for iron deficiency. Guidelines for Clinical Laboratory Practice CLP 002. North York (ON): OAML; 1995. Available at: http://www.oaml.com/ PDF/CLP002.pdf. Retrieved April 4, 2008.

CREATED 11/08/2008

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