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==Laboratory Findings==
==Laboratory Findings==
===Iron studies===
* Complete blood count- Hb <10.5mg/dl and MCV <95fL.
* Iron studies should  be done in patients with [[microcytic anemia]] to confirm the diagnosis of [[iron deficiency anemia]]. The tests usually done for iron deficiency anemia are:
* Microcytic and hypochromic anemia on peripheral blood film.
** [[Serum iron]]- Decreased in iron deficiency
* Red cell distribution width increased.
** [[Transferrin]]- Elevated in iron deficiency
* Reticulocyte count is low.
** [[Total iron binding capacity]] ([[TIBC]])- Elevated in iron deficiency.  
* Iron studies:
** [[Transferrin saturation]]- derived by dividing the serum iron by the TIBC. Decreased in iron deficiency.  
** Iron stain (prussian blue staining) of erythroid precursors (sideroblasts) on marrow spicules shows ack of stainable iron in erythroid precursors.
** [[Ferritin]]- Indicator of body iron stores and is low in iron deficiency. However, ferritin also acts as an [[acute phase reactant]] and can be unreliable in inflammatory illness.  
** Serum ferittin levels < 30ng/ml, and serum ferritin <41 ng/mL in a patient with anemia and comorbidities (chronic diseases/inflammation)
** Serum iron '''<60 mcg/dL.'''
** Total iron binding capacity/ serum transferrin- TIBC is calculated by multiplying serum transferrin by 1.389. It is increased in iron deficiency anemia and decreased in anemia of chronic disease. TIBC>'''350 to 400 mcg/dL''' is diagnostic of iron deficiency.
** Transferrin saturation (TSAT) is the ratio of serum iron to TIBC: (serum iron  ÷  TIBC  x  100). It is <15% in iron deficiency (normal is 25-40%).
* Elevated erythrocyte (RBC) zinc protoporphyrin (eg, >80 mcg/dL).
* Decreased iron stain on eryhtroid precursors.
 
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==General facts==
* Although all of these tests can be used to assess [[iron]] status, no single test is accepted for diagnosing iron deficiency.
* Lack of standardization among the tests and a paucity of laboratory proficiency testing limit comparison of results between laboratories.
* Laboratory proficiency testing is currently available for measuring Hb concentration, [[hematocrit]], [[red blood cell]] count, serum [[ferritin]] concentration, and serum iron concentration, [[total iron-binding capacity]], [[erthrocyte protoporphryin concentration]].
* Regardless of whether test standardization and proficiency testing become routine, better understanding among health-care providers about the strengths and limitations of each test is necessary to improve screening for and diagnosis of [[iron-deficiency anemia]], especially because the results from all of these tests can be affected by factors other than iron status.
* Because of their low cost and the ease and rapidity in performing them, the tests most commonly used to screen for iron deficiency are Hb concentration and Hct).
* These measures reflect the amount of functional iron in the body.
* The concentration of the iron-containing protein Hb in circulating red blood cells is the more direct and sensitive measure.
* Hct indicates the proportion of whole blood occupied by the red blood cells; it falls only after the Hb concentration falls.
* Since, changes in Hb concentration and Hct occur only at the late stages of iron deficiency, both tests are late indicators of iron deficiency.
* Anemia will be diagnosed on the basis of suggestive symptoms, or found on the basis of routine testing, which includes a [[complete blood count]] (CBC).
*  A sufficiently low [[hemoglobin]] or [[hematocrit]] value is diagnostic of anemia, and further studies will be undertaken to determine its cause.
* One of the first abnormal values to be noted on a CBC will be a high [[red blood cell distribution width]] (RDW), reflecting a varied size distribution of [[erythrocytes|red blood cells]].
* The diagnosis of iron deficiency anemia will be suggested by appropriate history (e.g., anemia in a menstruating woman), and by such diagnostic tests as a low serum [[ferritin]], a low serum [[iron]] level, an elevated serum [[transferrin]] and a high [[total iron binding capacity]] (TIBC). [[Serum]] ferritin is the most [[sensitivity (tests)|sensitive]] lab test for [[iron deficiency anemia]].<ref>{{cite journal | author = Guyatt G, Patterson C, Ali M, Singer J, Levine M, Turpie I, Meyer R | title = Diagnosis of iron-deficiency anemia in the elderly. | journal = Am J Med | volume = 88 | issue = 3 | pages = 205-9 | year = 1990 | id = PMID 2178409}}</ref>
* It is possible that the [[fecal occult blood]] test might be positive, if iron deficiency is the result of [[gastrointestinal bleeding]].
* Laboratory values have to be interpreted with the lab's [[reference values]] in mind and considering all aspects of the individual clinical situation.
* Serum [[ferritin]] can be elevated in inflammatory conditions and so a normal serum ferritin may not always exclude iron deficiency.


==References==
==References==

Revision as of 20:23, 22 August 2018

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.D. [2]

Overview

Iron status can be assessed through several laboratory tests. Since, each test assesses a different aspect of iron metabolism, results of one test may not always agree with results of other tests. Hematological tests based on characteristics of red blood cells (i.e., Hb concentration, hematocrit, mean cell volume, and red blood cell distribution width) are generally more available and less expensive than are biochemical tests. Biochemical tests (i.e., erythrocyte protoporphyrin concentration, serum ferritin concentration, and transferrin saturation), however, detect earlier changes in iron status. Except for Total iron binding capacity TIBC, transferrin saturation, and soluble transferrin receptor all other components of iron study are decreased in iron deficiency anemia. The soluble transferrin receptor test is a newer test and is found useful in distinguishing iron deficiency anemia from anemia of chronic disease.

Laboratory Findings

  • Complete blood count- Hb <10.5mg/dl and MCV <95fL.
  • Microcytic and hypochromic anemia on peripheral blood film.
  • Red cell distribution width increased.
  • Reticulocyte count is low.
  • Iron studies:
    • Iron stain (prussian blue staining) of erythroid precursors (sideroblasts) on marrow spicules shows ack of stainable iron in erythroid precursors.
    • Serum ferittin levels < 30ng/ml, and serum ferritin <41 ng/mL in a patient with anemia and comorbidities (chronic diseases/inflammation)
    • Serum iron <60 mcg/dL.
    • Total iron binding capacity/ serum transferrin- TIBC is calculated by multiplying serum transferrin by 1.389. It is increased in iron deficiency anemia and decreased in anemia of chronic disease. TIBC>350 to 400 mcg/dL is diagnostic of iron deficiency.
    • Transferrin saturation (TSAT) is the ratio of serum iron to TIBC: (serum iron  ÷  TIBC  x  100). It is <15% in iron deficiency (normal is 25-40%).
  • Elevated erythrocyte (RBC) zinc protoporphyrin (eg, >80 mcg/dL).
  • Decreased iron stain on eryhtroid precursors.
Change in lab values in iron deficiency anemia
Change Parameter
Decrease ferritin, hemoglobin, MCV
Increase TIBC, transferrin, RDW

References

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