Hemólisis extravascular Las reacciones más importantes relacionadas con una A ello contribuyen tanto el shock y la coagulación intravascular diseminada. Anemia Intravascular y Extravascular. Uploaded by Analia Vilca Tejerina. Save. Embed. Share. Print. RELATED TITLES. Download of K views. 0. Thus, intravascular hemolysis is identified by hemoglobinemia (not due to So, all patients with hemolytic anemia have extravascular hemolysis (usually the.
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Assessment of regeneration is the first step in working up an anemia and helps identify the mechanism for an anemia. These can be differentiated in most instances on the basis of history, clinical findings, and other laboratory results RBC morphologic features, total protein, iron parameters, bilirubin — see diagnostic algorithmn.
An unexpectedly low or inadequate regenerative response in an anemia that is primarily due to hemorrhage or hemolysis should prompt a search for underlying causes of bone marrow suppression, e. External and internal blood loss can also be acute or chronic in nature. Hemorrhage is usually associated with a low total protein, particularly external hemorrhage.
Total protein may not be low with internal hemorrhage e.
Iron deficiency will dampen the regenerative response many iron deficiency anemias are non-regenerative and are usually associated with microcytic hypochromic RBC indices and evidence of hypochromasia and RBC fragmentation, including acanthocytesschistocytes and keratocyteson blood smears, particularly in dogs.
Red blood cells are destroyed when they are prematurely removed from the circulation by macrophages, which phagocytize the cells before their normal lifespan is up. This is called extravascular hemolysis and the phagocytosis by macrophages is occurring within the spleen, in particular, but also other organs such as the liver and bone marrow. Extravascular hemolysis phagocytosis of RBC by macrophages is always occurring in a hemolytic anemia. Because iron is also high in RBCs and iron increases in serum with increased RBC turnover as occurs in a hemolytic anemiaj can also see high iron and iron saturation total iron binding extravaacular is normal in a hemolytic anemia.
Total protein is usually not decreased like it can be in hemorrhage. Also, a hemolytic anemia can induce a stronger regenerative response than a hemorrhagic anemia particularly that due to external hemorrhage and if a blood smear is examined, a cause for the hemolytic anemia may be identified e.
RBC shape change, presence of an erythroparasite. Extravascular hemolysis occurs when RBCs are phagocytized by macrophages in the spleen, liver and intravaecular marrow see image of an erythrophage to the right.
In some patients with some diseases, it may be accompanied by intravascular hemolysis luckily this does not happen too often as intravascular hemolysis is bad for a patient because it can cause acute renal injury. However, this is a physiologic process and does not result in anemia or excessive unconjugated bilirubin production.
When the membrane of erythrocytes rupture, they release their hemoglobin into the plasma. We may also see ghost RBCs in blood smears — these are RBCs that consist only of membrane remnants ghosts of their former cells because they have ruptured and released their hemoglobin. However, these are only usually obvious when there is a decent amount of intravascular hemolysis occurring.
We also see hemoglobinemia in all samples collected from the patient EDTA, clot tube, heparin, citrate — depending on the tests requested. The dog concurrently had marked hemoglobinuria as shown in the image to the right. Note that such hemolysis will interfere with clinical pathologic test results, including hemogram results. In an animal with intravascular hemolysis, the result that reflects oxygen-carrying capacity or oxygen that can be delivered to tissues on a hemogram is the RBC count because the hemoglobin measurement reflects both that within the RBCs the machine lyses the intact RBCs to liberate hemoglobin and that already in plasma which cannot carry oxygen to tissues.
A packed cell volume PCV is likely more accurate than the HCT because it is a directly measured value as long as we can still manually detect the top of the RBC layer in the microhematocrit tube, which can be difficult in animals with severe hemolysis.
Renal conjugation of bilirubin.
Thus we can detect the presence of a concurrent intravascular hemolysis if we see hemoglobinemia and hemoglobinuria in an anemic patient. However, we can only make this conclusion, if we rule out in vitro false intravascularr first. Intravascular hemolysis is not good for the patient.
Extravascuular results in acute kidney injury because free hemoglobin is nephrotoxic. The mechanisms of this nephrotoxicity is multifold. Free hemoglobin in plasma scavenges nitric oxide which is an important vasodilator of the renal medulla the part of the kidney that works the hardest. This results in renal ischemia and acute tubular injury or necrosis.
The hemoglobin that is filtered into urine also gets taken up by the renal tubules. Within the tubules, free iron can be liberated resulting in free radical injury. You can actually see hemoliiss hemoglobin within the tubules in patients with severe intravascular hemolysis and it is called a hemoglobinuric nephropathy heme is toxic to tubules, causing oxidant injury, and also scavenges nitric oxide, an important vasodilator in the renal medulla.
Therefore, the presence of intravascular hemolysis in an animal with a hemolytic anemia usually indicates a poorer prognosis. In vivo hdmolisis in vitro hemolysis Note that RBCs can also lyse or rupture in vitro either in the blood collection tube or during collection.
Artifactual hemolysis results from poor venipuncture technique, prolonged blood storage, exposure to temperature extremes hot or cold enough extravasculwr freeze the cellsand certain anticoagulants fluoride-oxalate will cause artifactual red blood cell lysis. Red blood cells are also more fragile in lipemic samples and tend to lyse more readily in these samples, even if intravscular blood is stored or handled correctly.
This artifactual red blood cell lysis can mimic intravascular intravaxcular and it can be very difficult to tell them apart particularly in the estravascular where all we see is the sample and not the patient. They both will result in hemoglobinemia and ghost cells. However, if the animal is anemic and has hemoglobinuria, true intravascular intravascuular, i. In the laboratory, we can also sometimes tell if intravascullar in plasma is an artifact.
We see this frequently in mailed in samples in the dead of winter, where samples may freeze during shipping. We frequently see more hemolysis in serum samples than plasma samples, because RBCs are ruptured manually during removal of serum from the clot.
With both in vivio or in vitro hemolysis, the MCH and MCHC may be falsely increased because hemoglobin is the common numerator for these calculated indices and is higher than the denominators, which are RBC count and HCT, respectively.
We use a variety of clinical and laboratory features to help us distinguish between these causes of a regenerative anemia. These include evaluation of the patient for evidence of hemorrhage external hemorrhage can be far more obvious than internal hemorrhage, unless it is mild or intermittenthematologic results specifically, red blood cell morphologic changes compatible with hemolytic anemia if they are present in sufficient numbersand chemistry results specifically, proteinbilirubin and iron panel results.
Note that additional tests may be required to document hemorrhage, e.
A low total protein due to combined decreases in albumin and globulins is expected but not inevitably present in animals with hemorrhage, particularly external, but also acute internal hemorrhage. However, other disease processes, e. This will occur if production exceeds the ability of the liver to take up and conjugate the unconjugated bilirubin presented to it.
Therefore, in an uncomplicated hemolytic anemia most hemolytic anemias in ruminants and horsesunconjugated bilirubin dominates with minimal increases in conjugated direct bilirubin. In some small animal patients with hemolytic anemia particularly dogs with immune-mediated hemolytic anemiaconjugated bilirubin may dominate because of concurrent cholestasis mechanisms, unclearhowever unconjugated bilirubin will still be increased.
Hemlisis chronic external hemorrhage, iron is lost concurrently with RBC. Ultimately, distinction between hemorrhage extrravascular hemolysis requires documentation of a source of bleeding and a decision by the clinician as to whether this is serious or severe enough to result in the anemia frequently a judgement call.
In some animals, identifying the exact mechanism of the anemia can be difficult and there may be multifactorial causes for anemia, e. The table intravscular summarizes these changes. Decreased or ineffective bone marrow production of erythroid cells will result in a non-regenerative anemia. Remember that, with acute hemorrhage or hemolysis, a regenerative response may not be seen for 3 to 5 days, especially if the anemia is mild to moderate, i.
Mechanisms and causes of non-regenerative anemia have been reviewed Grimes and Fry There are different causes of non-regenerative anemia, which may have overlapping mechanisms.
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Since marrow production is defective in non-regenerative anemia, a bone marrow aspirate may be indicated for specific diagnosis or to narrow down the differential diagnostic listdetermination of the underlying cause of the anemia, prognosis, and treatment. In general, a bone marrow is not indicated if the anemia is mild to moderate and the animal has a disease process that does not primarily involve the marrow, e. A marrow is indicated if the anemia is moderate to severe, other cytopenias neutropenia and thrombocytopenia are present, abnormal cells are detected in circulation, or there is no other explanation for the anemia.
Note that many animals have anemia due to multifactorial causes e. In these cases, the anemia may be more severe than can be attributed to a single cause alone or the degree of regeneration is unexpectedly low for intravasclar hemorrhagic or hemolytic anemia.
The following features are helpful to determine the cause of the non-regenerative anemia see diagnostic algorithm:. Diagnostic algorithm for a regenerative anemia. Oxidant-induced extfavascular anemia in a cat. Diagnostic algorithm for a non-regenerate anemia.
Thank you Your feedback has been received. RBC result reflecting oxygen-carrying capacity. Ghost cells can be an artifact of smear preparation in any blood smear.