Anemia

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Resident
Survival
Guide

Anemia main page

Overview

Classification

Differential Diagnosis

Medical Therapy

For patient information click here

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1], Associate Editor(s)-in-Chief: Sargun Singh Walia M.B.B.S.[2], Vamsikrishna Gunnam M.B.B.S[3], Mehrian Jafarizade, M.D [4]


Synonyms and Keywords: Anaemia; low hemoglobin; low hemoglobin levels (peripheral blood)

Overview

Anemia is the most common disorder of the blood. Anemia, from the Greek (Ἀναιμία) (an-haîma) meaning "without blood", is a deficiency of red blood cells (RBCs) and/or hemoglobin. This results in a reduced ability of blood to transfer oxygen to the tissues, causing tissue hypoxia. Since all human cells depend on oxygen for survival, varying degrees of anemia can have a wide range of clinical consequences. Hemoglobin (the oxygen-carrying protein in the red blood cells) has to be present to ensure adequate oxygenation of all tissues and organs.

The three main classes of anemia include excessive blood loss (acutely such as a hemorrhage or chronically through low-volume loss), excessive blood cell destruction (hemolysis) or deficient red blood cell production (ineffective hematopoiesis). Anemia is defined as a hemoglobin concentration (Hb) of less than 12 g/dL in women and less than 13 g/dL in men or hematocrit of 36% in women and 40% in men.

Classification

Here is a simplified schematic of this approach:

 
 
 
 
 
 
 
 
Anemia
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Reticulocyte production index shows inadequate production response to anemia.
 
 
 
Reticulocyte production index shows appropriate response to anemia = ongoing hemolysis or blood loss without RBC production problem.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
No clinical findings consistent with hemolysis or blood loss: pure disorder of production.
 
Clinical findings and abnormal MCV: hemolysis or loss and chronic disorder of production*.
 
Clinical findings and normal MCV= acute hemolysis or loss without adequate time for bone marrow production to compensate**.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Macrocytic anemia (MCV>100)
 
Normocytic anemia (80<MCV<100)
 
 
Microcytic anemia (MCV<80)
 
 
 
 

* For instance, sickle cell anemia with superimposed iron deficiency; chronic gastric bleeding with B12 and folate deficiency; and other instances of anemia with more than one cause. ** Confirm by repeating reticulocyte count: ongoing combination of low reticulocyte production index, normal MCV and hemolysis or loss may be seen in bone marrow failure or anemia of chronic disease, with superimposed or related hemolysis or blood loss.

Classification Based on Red blood Cell Size

Here is a schematic representation of how to consider anemia with MCV as the starting point:

 
 
 
 
 
 
 
 
 
 
 
Anemia
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Macrocytic anemia (MCV>100)
 
 
 
 
 
Normocytic anemia (80<MCV<100)
 
 
 
 
 
Microcytic anemia (MCV<80)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
High reticulocyte count
 
 
 
 
 
Low reticulocyte count
 
 
 
 

Other characteristics visible on the peripheral smear may provide valuable clues about a more specific diagnosis; for example, abnormal white blood cells may point to a cause in the bone marrow.

Microcytic Anemia

Microcytic anemia is primarily a result of hemoglobin synthesis failure/insufficiency, which could be caused by several etiologies:

  • Iron deficiency anemia is the most common type of anemia overall and it has many causes. RBCs often appear hypochromic (paler than usual) and microcytic (smaller than usual) when viewed with a microscope.
  • Hemoglobinopathies - much rarer (apart from communities where these conditions are prevalent)

Normocytic Anemia

Normocytic anaemia occurs when the overall Hb levels are decreased, but the red blood cell size (MCV) remains normal. Causes include:

Macrocytic Anemia

Specific Anemias

Differentiating Anemia from Other Diseases

Anemia must be differentiated based on different laboratory findings including mean cell volume (MCV), reticulocytosis, and hemolysis.

To review the differential diagnosis of anemia, see below table.

To review the differential diagnosis of microcytic anemia, click here.

To review the differential diagnosis of normocytic anemia, click here.

To review the differential diagnosis of macrocytic anemia, click here.

To review the differential diagnosis of hypochromic anemia, click here.

To review the differential diagnosis of normochromic anemia, click here.

To review the differential diagnosis of anisochromic anemia, click here.

To review the differential diagnosis of hemolytic anemia, click here.

To review the differential diagnosis of anemia with intrinsic hemolysis, click here.

To review the differential diagnosis of anemia with extrinsic hemolysis, click here.

To review the differential diagnosis of anemia with low reticulocytosis, click here.

To review the differential diagnosis of anemia with normal reticulocytosis, click here.

To review the differential diagnosis of anemia with high reticulocytosis, click here.

Disease Genetics Clinical manifestation Lab findings
History Symptoms Signs Hemolysis Intrinsic/

Extrinsic

Hb concentration MCV RDW Reticulocytosis Haptoglobin levels Hepcidin Iron studies Specific finding on blood smear
Serum iron Serum Tfr level Transferrin or TIBC Ferritin Transferrin saturation
Iron deficiency anemia[1] Hypochromic Microcytic Nl or ↓ Nl Nl ↓↓↓
Iron deficiency anemia (early phase)[2] Normochromic Normocytic Nl Nl
Lead poisoning[3]
  • House painted with chipped paint
Hypochromic Microcytic Nl Nl or ↓ Nl Nl Nl to ↓ Nl Nl Nl to ↓
  • RBCs retain aggregates of rRNA
  • Basophilic stippling
Sideroblastic anemia[4] Hypochromic Microcytic Nl Nl or ↓ Nl Nl Nl Nl to ↓
Disease Genetics History Symptoms Signs Hemolysis Intrinsic/

Extrinsic

Hb concentration MCV RDW Reticulocytosis Haptoglobin levels Hepcidin Serum iron Serum Tfr level IBC Ferritin Transferrin saturation Specific finding on blood smear
Anemia of chronic disease[5] Hypochromic Microcytic Nl Nl or ↓ Nl Nl NA
Thalassemia[6] α-thalassemia
  • α- globin gene deletions
  • Cis deletions
  • Trans deletions

β-thalassemia

α-thalassemia

β-thalassemia

Hypochromic Microcytic Nl
  • Thalassemia trait: Nl or ↓
  • Thalassemia Syndromes: ↑
Nl Nl Nl to ↑ Nl Nl Nl to ↑
G6pd deficiency[7]
  • History of using
+ Intrinsic Normochromic Normocytic ↑ but usually causes resolution within 4-7 days Nl to ↑ Nl
Pyruvate kinase deficiency[8] + Intrinsic Normochromic Normocytic Nl Nl Nl
Disease Genetics History Symptoms Signs Hemolysis Intrinsic/

Extrinsic

Hb concentration MCV RDW Reticulocytosis Haptoglobin levels Hepcidin Serum iron Serum Tfr level IBC Ferritin Transferrin saturation Specific finding on blood smear
Sickle cell anemia[9] + Intrinsic Normochromic Normocytic Nl or moderately ↑ Nl Nl Nl or moderately ↑ Nl
HbC disease[10]
  • Glutamic acid–to-lysine mutation in β-globin
+ Intrinsic Normochromic Normocytic Nl Nl Nl Nl
Paroxysmal nocturnal hemoglobinuria[11][12] + Intrinsic Normochromic Normocytic Nl Nl NA
Hereditary spherocytosis[13] + Intrinsic Normochromic Normocytic Nl Nl Nl
  • Small, round RBCs with less surface area and no central pallor
Disease Genetics History Symptoms Signs Hemolysis Intrinsic/

Extrinsic

Hb concentration MCV RDW Reticulocytosis Haptoglobin levels Hepcidin Serum iron Serum Tfr level IBC Ferritin Transferrin saturation Specific finding on blood smear
Microangiopathic hemolytic anemia[14][15] Associated with + Extrinsic Normochromic Normocytic Nl Nl
  • Helmet cells
Macroangiopathic hemolytic anemia[16] Associated with + Extrinsic Normochromic Normocytic Nl Nl
Autoimmune hemolytic anemia[17] Associated with:
  • Painful, blue fingers and toes with cold weather
+ Extrinsic Normochromic Normocytic Nl Nl
  • RBC agglutination
Aplastic anemia[18]
  • Symptoms based on underlying condition
Normochromic Normocytic Nl Nl Nl
Disease Genetics History Symptoms Signs Hemolysis Intrinsic/

Extrinsic

Hb concentration MCV RDW Reticulocytosis Haptoglobin levels Hepcidin Serum iron Serum Tfr level IBC Ferritin Transferrin saturation Specific finding on blood smear
Folate deficiency[19]
  • Impaired DNA synthesis
Anisochromic Macrocytic Nl Nl
Vitamin B12 deficiency[20] Anisochromic Macrocytic Nl Nl
Orotic aciduria[21]
  • Neurological manifestation
Anisochromic Macrocytic Nl Nl NA
Fanconi anemia[22]
  • Significant for bilateral short thumbs
Anisochromic Macrocytic Nl Nl
Disease Genetics History Symptoms Signs Hemolysis Intrinsic/

Extrinsic

Hb concentration MCV RDW Reticulocytosis Haptoglobin levels Hepcidin Serum iron Serum Tfr level IBC Ferritin Transferrin saturation Specific finding on blood smear
Diamond-Blackfan anemia[23] Mutations in:
  • RPL5
  • RPL11
  • RPL35A
  • RPS7
  • RPS10
  • RPS17
  • RPS19
  • RPS24
  • RPS26
Anisochromic Macrocytic Nl Nl Nl NA
Infections[24] Associated with + Extrinsic Normochromic Normocytic Nl Nl Nl
Chronic kidney disease[25] Normochromic Normocytic Nl/↑ Nl Nl
Liver disease[26]
  • Hepatitis
  • Binge drinking
  • Gall bladder disease
Anisochromic Macrocytic Nl Nl
Alcoholism[27] Anisochromic Macrocytic Nl Nl
Disease Genetics History Symptoms Signs Hemolysis Intrinsic/

Extrinsic

Hb concentration MCV RDW Reticulocytosis Haptoglobin levels Hepcidin Serum iron Serum Tfr level IBC Ferritin Transferrin saturation Specific finding on blood smear

Medical Therapy

If hemodynamic compromise is present, then immediate intervention is required which includes:

  • Administration of O2 as needed
  • Iron, folate, vitamin B12 supplements as necessary
  • IV fluids for maintenance of blood pressure
  • For hemoglobins <8 gm/dl, blood transfusions are indicated
  • Establishment of two large-bore IVs for cases of ongoing acute blood loss

There are many different treatments for anemia and the treatment depends on severity and the cause.

Iron deficiency from nutritional causes is rare in non-menstruating adults (men and post-menopausal women). The diagnosis of iron deficiency mandates a search for potential sources of loss such as gastrointestinal bleeding from ulcers or colon cancer. Mild to moderate iron deficiency anemia is treated by iron supplementation with ferrous sulfate or ferrous gluconate. Vitamin C may aid in the body's ability to absorb iron.

Vitamin supplements given orally (folic acid) or subcutaneously (vitamin b-12) will replace specific deficiencies.

In anemia of chronic disease, anemia associated with chemotherapy, or anemia associated with renal disease, some clinicians prescribe recombinant erythropoietin, epoetin alfa, to stimulate red cell production.

In severe cases of anemia, or with ongoing blood loss, a blood transfusion may be necessary.

Contraindicated medications

Severe anemia is considered an absolute contraindication to the use of the following medications:

Blood Transfusions

Doctors attempt to avoid blood transfusion in general, since multiple lines of evidence point to increased adverse patient clinical outcomes with more intensive transfusion strategies. The physiological principle that reduction of oxygen delivery associated with anemia leads to adverse clinical outcomes is balanced by the finding that transfusion does not necessarily mitigate these adverse clinical outcomes.

In severe, acute bleeding, transfusions of donated blood are often lifesaving. Improvements in battlefield casualty survival is attributable, at least in part, to the recent improvements in blood banking and transfusion techniques.

Transfusion of the stable but anemic hospitalized patient has been the subject of numerous clinical trials, and transfusion is emerging as a deleterious intervention.

Four randomized controlled clinical trials have been conducted to evaluate aggressive versus conservative transfusion strategies in critically ill patients. All four of these studies failed to find a benefit with more aggressive transfusion strategies. [28][29][30][31]

In addition, at least two retrospective studies have shown increases in adverse clinical outcomes with more aggressive transfusion strategies.[32] [33]

On the whole, these studies suggest that aggressive transfusions, at least for hospitalized patients, may at best not improve any clinical parameter, and at worst lead to adverse outcomes.

A recent report suggests that the culprit is the depletion of nitric oxide, an important vasodilator, in banked blood. The theory is that the transfusion of nitric oxide-depleted blood causes systemic vasoconstriction, and exacerbates hypoxia in tissues at risk.[34]

References

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  2. De Andrade Cairo RC, Rodrigues Silva L, Carneiro Bustani N, Ferreira Marques CD (June 2014). "Iron deficiency anemia in adolescents; a literature review". Nutr Hosp. 29 (6): 1240–9. PMID 24972460. doi:10.3305/nh.2014.29.6.7245. 
  3. Bain BJ (December 2014). "Lead poisoning". Am. J. Hematol. 89 (12): 1141. PMID 25220013. doi:10.1002/ajh.23852. 
  4. Bottomley SS, Fleming MD (August 2014). "Sideroblastic anemia: diagnosis and management". Hematol. Oncol. Clin. North Am. 28 (4): 653–70, v. PMID 25064706. doi:10.1016/j.hoc.2014.04.008. 
  5. Roy CN (2010). "Anemia of inflammation". Hematology Am Soc Hematol Educ Program. 2010: 276–80. PMID 21239806. doi:10.1182/asheducation-2010.1.276. 
  6. Zainal NZ, Alauddin H, Ahmad S, Hussin NH (December 2014). "α-Thalassemia with Haemoglobin Adana mutation: prenatal diagnosis". Malays J Pathol. 36 (3): 207–11. PMID 25500521. 
  7. Luzzatto L, Seneca E (February 2014). "G6PD deficiency: a classic example of pharmacogenetics with on-going clinical implications". Br. J. Haematol. 164 (4): 469–80. PMC 4153881Freely accessible. PMID 24372186. doi:10.1111/bjh.12665. 
  8. Grace RF, Zanella A, Neufeld EJ, Morton DH, Eber S, Yaish H, Glader B (September 2015). "Erythrocyte pyruvate kinase deficiency: 2015 status report". Am. J. Hematol. 90 (9): 825–30. PMC 5053227Freely accessible. PMID 26087744. doi:10.1002/ajh.24088. 
  9. Singh PC, Ballas SK (March 2015). "Emerging drugs for sickle cell anemia". Expert Opin Emerg Drugs. 20 (1): 47–61. PMID 25431087. doi:10.1517/14728214.2015.985587. 
  10. Lemonne N, Billaud M, Waltz X, Romana M, Hierso R, Etienne-Julan M, Connes P (2016). "Rheology of red blood cells in patients with HbC disease". Clin. Hemorheol. Microcirc. 61 (4): 571–7. PMID 25335812. doi:10.3233/CH-141906. 
  11. Bunyaratvej A, Butthep P (January 1992). "Cytometric analysis of paroxysmal nocturnal hemoglobinuria erythrocytes". J Med Assoc Thai. 75 Suppl 1: 237–42. PMID 1402472. 
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  13. Da Costa L, Galimand J, Fenneteau O, Mohandas N (July 2013). "Hereditary spherocytosis, elliptocytosis, and other red cell membrane disorders". Blood Rev. 27 (4): 167–78. PMID 23664421. doi:10.1016/j.blre.2013.04.003. 
  14. Morishita E (July 2015). "[Diagnosis and treatment of microangiopathic hemolytic anemia]". Rinsho Ketsueki (in Japanese). 56 (7): 795–806. PMID 26251142. doi:10.11406/rinketsu.56.795. 
  15. George JN, Charania RS (March 2013). "Evaluation of patients with microangiopathic hemolytic anemia and thrombocytopenia". Semin. Thromb. Hemost. 39 (2): 153–60. PMID 23390027. doi:10.1055/s-0032-1333538. 
  16. Westphal RG, Azen EA (May 1971). "Macroangiopathic hemolytic anemia due to congenital cardiovascular anomalies". JAMA. 216 (9): 1477–8. PMID 5108522. 
  17. Hill QA (October 2015). "Autoimmune hemolytic anemia". Hematology. 20 (9): 553–4. PMID 26447931. doi:10.1179/1024533215Z.000000000401. 
  18. Dolberg OJ, Levy Y (2014). "Idiopathic aplastic anemia: diagnosis and classification". Autoimmun Rev. 13 (4-5): 569–73. PMID 24424170. doi:10.1016/j.autrev.2014.01.014. 
  19. Koike H, Takahashi M, Ohyama K, Hashimoto R, Kawagashira Y, Iijima M, Katsuno M, Doi H, Tanaka F, Sobue G (March 2015). "Clinicopathologic features of folate-deficiency neuropathy". Neurology. 84 (10): 1026–33. PMID 25663227. doi:10.1212/WNL.0000000000001343. 
  20. Hunt A, Harrington D, Robinson S (September 2014). "Vitamin B12 deficiency". BMJ. 349: g5226. PMID 25189324. 
  21. Grohmann K, Lauffer H, Lauenstein P, Hoffmann GF, Seidlitz G (April 2015). "Hereditary orotic aciduria with epilepsy and without megaloblastic anemia". Neuropediatrics. 46 (2): 123–5. PMID 25757096. doi:10.1055/s-0035-1547341. 
  22. Alter BP (2014). "Fanconi anemia and the development of leukemia". Best Pract Res Clin Haematol. 27 (3-4): 214–21. PMC 4254647Freely accessible. PMID 25455269. doi:10.1016/j.beha.2014.10.002. 
  23. Vlachos A, Blanc L, Lipton JM (June 2014). "Diamond Blackfan anemia: a model for the translational approach to understanding human disease". Expert Rev Hematol. 7 (3): 359–72. PMID 24665981. doi:10.1586/17474086.2014.897923. 
  24. Bustinduy AL, Parraga IM, Thomas CL, Mungai PL, Mutuku F, Muchiri EM, Kitron U, King CH (March 2013). "Impact of polyparasitic infections on anemia and undernutrition among Kenyan children living in a Schistosoma haematobium-endemic area". Am. J. Trop. Med. Hyg. 88 (3): 433–40. PMC 3592521Freely accessible. PMID 23324217. doi:10.4269/ajtmh.12-0552. 
  25. Drawz P, Rahman M (June 2015). "Chronic kidney disease". Ann. Intern. Med. 162 (11): ITC1–16. PMID 26030647. doi:10.7326/AITC201506020. 
  26. Marks PW (July 2013). "Hematologic manifestations of liver disease". Semin. Hematol. 50 (3): 216–21. PMID 23953338. doi:10.1053/j.seminhematol.2013.06.003. 
  27. Yokoyama A, Yokoyama T, Brooks PJ, Mizukami T, Matsui T, Kimura M, Matsushita S, Higuchi S, Maruyama K (May 2014). "Macrocytosis, macrocytic anemia, and genetic polymorphisms of alcohol dehydrogenase-1B and aldehyde dehydrogenase-2 in Japanese alcoholic men". Alcohol. Clin. Exp. Res. 38 (5): 1237–46. PMID 24588059. doi:10.1111/acer.12372. 
  28. Hébert PC, Wells G, Blajchman MA; et al. (1999). "A multicenter, randomized, controlled clinical trial of transfusion requirements in critical care. Transfusion Requirements in Critical Care Investigators, Canadian Critical Care Trials Group". N. Engl. J. Med. 340 (6): 409–17. PMID 9971864. 
  29. Bush RL, Pevec WC, Holcroft JW (1997). "A prospective, randomized trial limiting perioperative red blood cell transfusions in vascular patients". Am. J. Surg. 174 (2): 143–8. PMID 9293831. 
  30. Bracey AW, Radovancevic R, Riggs SA; et al. (1999). "Lowering the hemoglobin threshold for transfusion in coronary artery bypass procedures: effect on patient outcome". Transfusion. 39 (10): 1070–7. PMID 10532600. 
  31. McIntyre LA, Fergusson DA, Hutchison JS; et al. (2006). "Effect of a liberal versus restrictive transfusion strategy on mortality in patients with moderate to severe head injury". Neurocritical care. 5 (1): 4–9. PMID 16960287. 
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  33. Vincent JL, Baron JF, Reinhart K; et al. (2002). "Anemia and blood transfusion in critically ill patients". JAMA. 288 (12): 1499–507. PMID 12243637. 
  34. MEDICAL SCIENCES S-nitrosohemoglobin deficiency: A mechanism for loss of physiological activity in banked blood James D. Reynolds*, Gregory S. Ahearn{dagger}, Michael Angelo{dagger}, Jian Zhang{dagger}, Fred Cobb{dagger},{ddagger}, and Jonathan S. Stamler Published online before print October 11, 2007 Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0707958104 Accessed 10/15/07

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