At the end of their normal life span about days , red blood cells RBCs are removed from the circulation. Anemia results when bone marrow production can no longer compensate for the shortened RBC survival; this condition is termed uncompensated hemolytic anemia. If the marrow can compensate, the condition is termed compensated hemolytic anemia. Extrinsic: From a source outside the red cell; disorders extrinsic to the RBC are usually acquired.
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Even though hemolytic anemias HAs are not very common, their diagnosis remains a big challenge for hematologists and clinicians. We hope that this summary will contribute with valuable information about a subject that has been little described in the medical literature, and will help to clarify the diagnostic approach to guide specific treatment depending on the causative condition.
It is known that HAs are a group of disorders characterized by a premature red blood cell RBC destruction less than days , 1 , 2 that exceeds the compensatory capacity of the bone marrow to increase RBC production and keep up with the loss.
Regarding the etiology, HAs can be classified as inherited or acquired and when considering the site of hemolysis, RBCs can be destroyed in the circulation intravascular or within macrophages in the spleen or liver extravascular. From the clinical perspective, HAs can be acute or chronic and according to the location of the abnormality responsible for the hemolysis, they may be due to intrinsic intracorpuscular or extrinsic extracorpuscular defects.
For example, paroxysmal nocturnal hemoglobinuria PNH is an acquired HA produced by an intrinsic defect 4 and glucosephosphate dehydrogenase G6PD deficiency is an inherited intrinsic defect that is triggered by an external factor. Although there are different ways of approaching the diagnosis of HAs, it is first necessary to identify the patient with HA and collect data on hemolysis. The destruction of RBCs in HAs is characterized by an increased breakdown of hemoglobin which results in unconjugated hyperbilirubinemia clinically evidenced by jaundice, increased lactate dehydrogenase cellular destruction , and reticulocytosis, which is a normal compensatory response of the bone marrow to the RBC loss.
Additionally, decreased levels of plasma haptoglobin, a marker of RBC destruction, are evidenced 1 , 2 , 3 regardless the site of hemolysis intravascular or extravascular. Once we have a presumptive diagnosis, a multi-step procedure is required, 4 beginning with a direct antiglobulin test DAT or direct Coombs test.
A simple approach to identify and classify hemolytic anemias. In cases of immune HAs DAT positive , the diagnostic possibilities are limited to the presence of autoantibodies warm, cold or mixed , alloimmunization as in transfusion incompatibility , or drug-related hemolysis by haptens, autoantibodies or immune complexes.
Certain morphological abnormalities of RBCs correlate with different pathologies. For example, schistocytes are related to thrombotic microangiopathies or cardiac prosthetic valves, spherocytes with hereditary spherocytosis, sickled cells with sickle cell disease, elliptocytes with hereditary elliptocytosis, echinocytes with pyruvate kinase deficiency, Heinz bodies with G6PD deficiency, and basophilic stipplings with lead poisoning, thalassemia, and Wilson's disease, among others.
Likewise, traumatic hemolysis of big or small vessels , infectious Bartonella , Babesia , Plasmodium or toxic exogenous or endogenous pathologies should be taken into account if there is an abnormal PBS in the absence of family history.
A detailed list of the most common causes of hemolysis classified by type is presented in Table 1. National Center for Biotechnology Information , U. Rev Bras Hematol Hemoter. Published online Oct 9. Eloy F. Author information Article notes Copyright and License information Disclaimer.
Ruiz: ep. Received Jun 26; Accepted Aug Published by Elsevier Editora Ltda. All rights reserved. Dear Sir, Even though hemolytic anemias HAs are not very common, their diagnosis remains a big challenge for hematologists and clinicians. Open in a separate window. Figure 1. Table 1 The most common causes of hemolysis classified by type. Conflicts of interest The authors declare no conflicts of interest.
References 1. Evans E. Diagnosis of the hemolytic anemias. Calif Med. Ucar K. Clinical presentation and management of hemolytic anemias. Oncology Williston Park ; 16 9 Suppl 10 — Dhaliwal G.
Hemolytic anemia. Am Fam Physician. Guillaud C. Hemolytic anemia in adults: main causes and diagnostic procedures. Expert Rev Hematol. Shih A. Haptoglobin testing in hemolysis: measurement and interpretation. Am J Hematol. Zantek N. The direct antiglobulin test: a critical step in the evaluation of hemolysis. Bass G. Diagnosis and classification of autoimmune hemolytic anemia.
Hemolytic anemia is a form of anemia due to hemolysis , the abnormal breakdown of red blood cells RBCs , either in the blood vessels intravascular hemolysis or elsewhere in the human body extravascular. Symptoms of hemolytic anemia are similar to other forms of anemia fatigue and shortness of breath , but in addition, the breakdown of red cells leads to jaundice and increases the risk of particular long-term complications, such as gallstones  and pulmonary hypertension. Symptoms of hemolytic anemia are similar to the general signs of anemia. Chronic hemolysis leads to an increased excretion of bilirubin into the biliary tract , which in turn may lead to gallstones.
Diagnostic approach to hemolytic anemias in the adult
Overview of Hemolytic Anemia