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Hemolytic Anemias: General Considerations
Published in Harold R. Schumacher, William A. Rock, Sanford A. Stass, Handbook of Hematologic Pathology, 2019
8. Serum haptoglobin. The normal function of haptoglobin is to form a complex with free hemoglobin, and remove it to the reticuloendothelial system for metabolism. The quantity of haptoglobin present in blood is barely adequate to perform this function under normal conditions. During hemolysis, haptoglobin is rapidly consumed, and significantly reduced levels are detected (see Fig. 1). It is often said that haptoglobin is primarily a marker of intravascular hemolysis, but in fact it is a highly sensitive indicator of hemolysis in general. The positive predictive value of a low serum haptoglobin for predicting hemolysis is 87%; the negative predictive value (the likelihood that a patient with normal or elevated haptoglobin is not undergoing hemolysis) is 95% (12).
Biochemistry
Published in Michael McGhee, A Guide to Laboratory Investigations, 2019
Haptoglobin (normal range 500–1,900 mg/l is an alpha-2 globulin that is increased in acute inflammatory conditions and decreased in haemolysis. Normal liver enzymes and normal haptoglobin exclude hepatitis and haemolytic disease.
Physiology of blood
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2015
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Various proteins belong to this group of globulins are as follows: α 2-Macroglobulin is a protease inhibitor in plasma, and is the major protein in the α2-globulin fraction (∼80%). It has inhibitory functions on plasma trypsin, chymotrypsin and plasmin. The primary function of α2-macroglobulin may be to inhibit proteases produced by infectious organisms.Prothrombin is a clotting factor synthesized by the liver. About 60% of the extracellular pool of prothrombin is in the plasma and 40% in the extravascular space. It has a rapid turnover.Haptoglobin is a heterogeneous group of globulins that bind free Hb and transport it to the liver.Ceruloplasmin is a plasma protein that carries copper, and is produced in the liver. It also functions as an oxidase enzyme and oxidizes ferrous to ferric ions before the binding of iron to transferrin. As an acute-phase protein, it may modulate inflammation by its free radical scavenging properties.
Strategies to overcome the diagnostic challenges of autoimmune hemolytic anemias
Published in Expert Review of Hematology, 2023
Wilma Barcellini, Bruno Fattizzo
All the described hemolytic markers have several coexisting confounding conditions that may puzzle their interpretation [40]. Underdiagnosed blood loss, vitamin/iron deficiency, renal/liver disease, and erythropoietin insufficiency may contribute to anemia. LDH is increased in several diseases that involve cellular necrosis or increased tissue turnover (myocardial infarction, heart failure, hepatitis, extreme muscular effort, and solid and hematologic tumors). Unconjugated bilirubin is typically increased in Gilbert’s syndrome, and mixed hyperbilirubinemia in liver disease. Haptoglobin, may be falsely normal/raised in inflammatory diseases, cigarette smokers, and nephritic syndrome possibly masking an underlying hemolysis; conversely, it may be reduced for liver disease, malnutrition, and congenital hypo-haptoglobinemia, without a hemolytic disease. Reticulocytes, that are not ‘truly’ hemolytic markers, may be increased in other causes of anemia requiring bone marrow compensation, such as hemorrhage, pregnancy/delivery and acclimatation. At variance a coexisting underdiagnosed bone marrow disease (myelodysplasia, aplasia, leukemia, tumors) may impair an adequate reticulocyte compensation.
Hemolysis during short-term mechanical circulatory support: from pathophysiology to diagnosis and treatment
Published in Expert Review of Medical Devices, 2022
Tim Balthazar, Johan Bennett, Tom Adriaenssens
Haptoglobin is an acute-phase glycoprotein produced in the liver. Its major biological function is to bind – with high affinity – free hemoglobin in plasma, in order to prevent loss of iron molecules, on the one hand, and hemoglobin-mediated renal injury, on the other hand [21]. When circulating hemoglobin is bound to haptoglobin, renal excretion of hemoglobin is reduced, thereby decreasing the risk of injury to the kidney tubules. Therefore, haptoglobin levels are decreased or absent in cases of hemolysis. Normal values of the plasma range in a wide interval between 0.5 and 3.2 g/l. In cases of hemolysis, values <25 mg/dl are characteristic. However, one cannot estimate the severity of intravascular hemolysis based on haptoglobin levels, because of its limited capacity to bind free hemoglobin. Even a mild or moderate degree of RBC destruction will result in undetectable haptoglobin levels. Moreover, other confounding factors with respect to haptoglobin levels must be taken into account, such as decreased baseline levels in patients with liver disease (cirrhosis), abdominal trauma and congenital ahaptoglobinemia and increased levels in the setting of concomitant inflammatory states (role of haptoglobin as an acute-phase reactant) and the nephrotic syndrome [39].
Hb Mizuho (HBB: c.206T>C): Pitfalls of Screening Tests in an Unstable Hemoglobin Variant Diagnosed after Targeted Next-Generation Sequencing
Published in Hemoglobin, 2021
Diksha D. Yadav, Manu Jamwal, Namrata Singh, Ritika Sharma, Reena Das, Amita Trehan, Deepak Bansal, Sanjeev Chhabra, Prashant Sharma
A 2-year-old Indian Sikh boy with a history of neonatal jaundice presented with transfusion-dependent anemia since the age of 6 months along with moderate hepatosplenomegaly. There was no similar family history. The hemogram revealed moderate anemia (8.0 g/dL) with mean corpuscular volume (MCV) 94.1 fL, mean corpuscular Hb (MCH) 29.0 pg, red cell distribution width (RDW) 26.0%, and reticulocytosis (14.4% after correction). Peripheral smear showed moderate anisopoikilocytosis with normocytic normochromic red blood cells, a few microcytes, macrocytes, elliptocytes, dacryocytes, polychromatophils, and four erythroblasts per 100 leukocytes. Plasma Hb (45.0 mg/dL), indirect bilirubin (1.9 mg/dL), and LDH (480.0 U/L) were raised, but urine Hb, Coombs’ test, glucose-6-phosphate-dehydrogenase (G6PD)-deficiency screening, incubated osmotic fragility test and heat and isopropanol tests for unstable Hb were all negative/normal. Haptoglobin level was markedly reduced (<6.0 mg/dL).