Classification of Anemia Flashcards
How are different forms of anaemia classified?
Anemia is classified according to size and hemoglobin concentration. size - MCV hemoglobin - Hb
Define normocytic.
normal sized red blood cells
Define macrocytic.
abnormally large red blood cells
Define microcytic.
abnormally small red blood cells
Define normochromic.
normally colored red blood cells
Define hypochromic.
abnormally colored red blood cells
What forms of anemia can be identified by the size and color of the blood cells?
iron deficiency anemia, megaloblastic anemia
In what form of anemia does the bone marrow actively respond by increasing the production of red blood cells?
regenerative (responsive) anemia
Define anisocytosis.
A difference in size seen in red blood cells.
What findings denote a regenerative anemia?
polychromasia, reticulocytosis, hypercellular bone marrow and a low M/E ratio (if WBC normal or increased)
In what form of anemia is the bone marrow unable to respond?
nonregenerative anemia
What findings denote a nonregenerative anemia?
polychromasia and reticulocytosis absent
When is a bone marrow exam indicated?
A bone marrow exam is indicated if anemia without signs of bone marrow response (polychromasia, reticulocytosis).
Define M/E.
myloid/erythroid The ratio of red blood line cells to white blood line cells seen in a bone marrow exam.
Define hemorrhage.
The external loss of blood i.e. bleeding.
Define hemolysis.
The internal loss of blood via the destruction of blood cells by the body.
How are anemias classified according to pathophysiologic mechanism?
blood loss (hemorrhagic) anemias, anemias caused by accellerated RBC destruction (hemolytic), and anemias caused by decreased or defective erythropoieses
Define hemorrhagic anemia.
an anemia caused by blood loss
Define hemolytic anemia.
an anemia caused by accelerated RBC loss
What pathophysicalogic mechanisms cause regenerative anemias?
hemorrhage, hemolyisis
What pathophysicalogic mechanisms cause nonregenerative anemias?
decreased or defective erythropoiesis function in the bone marrow and/or the kidneys
What functions of the body do physical findings of anemia pertain to?
Clinical signs suggesting anemia are related to decreased oxygen transport capacity and physiologic adjustments made to increase the efficiency of the erythron and decrease the workload on the heart.
What are the clinical signs of anemia?
pale mucous membranes, weakness/loss of stamina, tachycardia/polypnea - especially after exercise, hybersensitivity to cold, heart murmur due to decreased viscosity and increased turbulence of the blood, shock (if 1/3) of blood volume is lost in a short period, icterus, hemoglobinuria, hemorrage, or fever depending on pathophysiologic mechanism involved
Under what conditions are signs of anemia less marked?
Signs of anemia are less marked if the onset is gradual and the animal can adapt to decreased RBC.
Why is laboratory confirmation necessary for a diagnosis of anemia?
Laboratory confirmation is necessary because anemias don’t always present clinical signs, and also to determine the severity of the anemia.
What methods are used to confirm a diagnosis of anemia in a labratory setting?
PCV - easiest and most accurate, must be interpreted with knowledge of the animal’s hydration state and any alteration by splenic contraction, hemoglobin concentration and RBC count are used to further classify the anemia
What does a finding of regenerative anemia suggest?
A finding of regenerative anemia suggests either blood loss or RBC destruction mechanism of sufficient duration (2-3 days) for response to be evident.
When is a bone marrow exam indicated for a regenerative anemia?
A bone marrow exam is the best means of detecting regenerative anemia in the horse. In all other cases it is rarely necessary as erythropoietic hyperplasia should be evident.
When is a regenerative response seen in a nonregenerative anemia?
A regenerative response is seen in the recovery stage of a nonregenerative anemia.
What does the presence of a nonregenerative anemia suggest?
A finding of nonregenerative anemia suggests a bone marrow or kidney disorder.
Why is a bone marrow exam indicated for a nonregenerative anemia?
A bone marrow exam is indicated to confirm and further classify the anemia.
What forms of regenerative anemia present a nonregenerative pattern?
Anemia caused by peracute or acute hemorrhage or hemolysis may present a nonregenerative pattern for the first 2-3 days after onset.
What findings indicate a diagnosis of hemorrhagic anemia?
Findings include clinical signs of hemorrhage, a regenerative response is seen after 2-3 days, and a decreased plasma protein concentration if the hemorrhage is external.
What are the differential features of external hemorrhage?
External hemmorage prevents reutilization of components (Fe, PP).
What are the differental features of internal hemorrhage?
About 2/3 of the RBCs in body cavities are reabsorbed into lymphatics after 24-72 hours. 1/3 are lysed or phagocytized and FE and PP are reutilized?
What factors affect the clinical signs of acute blood loss?
the amount of blood lost, the period of time, and site of hemmorage
Why is the PCV initially normal in cases of acute blood loss?
All blood components have been lost in equal proportions.
What may transitorily increase the PCV in cases of acute blood loss?
splenic contractions, as the blood contained within the spleen contains high PCV (80%) blood
What findings are seen in the platelets of cases of acute blood loss?
Platelet numbers usually increase in the first few hours but may be decreased if the consumption is extensive.
When are increased neutrophils seen in cases of acute blood loss?
Increased neutrophils commonly occur about three hours post-hemorrhage.
When do signs of blood volume restoration start in cases of acute blood loss?
Blood volume starts being restored by the addition of intestitial fluid within 2-3 hours of onset and proceeds 48-72 hours.
What causes labratory signs of anemia in cases of acute blood loss?
The dilution of RBCs due to the body’s blood volume replacement (using interstitial fluid) causes labratory signs of anemia.
In addition to the dilution of red blood cells, what laboratory findings are also seen in cases of acute blood loss?
TPP concentration decreases
When should signs of increased RBC production be evident in cases of acute blood loss?
Signs of increased RBC production are evident by 48-72 hours and for a maximum of 7 days after.
Why is the reticulocyte count higher in internal verses external hemorrhage?
The availability of iron determines the magnitude of reticulocytosis. Iron is reutilized directly in hemolytic anemias, whereas iron must be released from storage in cases of hemmorrhage.
When should the hemogram return to normal in the case of a single acute hemorrhage episode?
1-2 weeks
What should be suspected if increased reticulocytes are seen after 2-3 weeks in the case of a single acute hemorrhage episode?
continuous bleeding
What characteristics are seen in cases of chronic blood loss?
The anemia develops slowly (no hypovolemia), and the PCV can reach low values before clinical signs appear due to physiologic adaptation. Regenerative response and hypoproteinemia are usually observed.
Define hypoproteinemia.
abnormally low plasma protein in the blood
Why does iron-deficiency anemia develop in cases of chronic blood loss?
body stores of iron may be depleted after prolonged blood loss
How does iron-deficiency anemia affect clinical findings in cases of chronic blood loss?
Regenerative signs are less pronounced, and poikilocytosis is commonly present.
Define poikilocytosis.
a difference in shape among red blood cells
Why does iron deficiency anemia develop more readily in young animals?
Young animals have less storage of iron.
Why may blood marrow response end abrubtly in prolonged cases of chronic blood loss?
Blood marrow response may end due to nonregenerative iron deficiency anemia.
What is the first step in identifying the method of destruction in cases of hemolytic anemia?
determining the location of the site of hemolysis - intravascular or RE phagocytosis
What are the presumptive findings of hemolytic anemia?
regenerative response, normal TPP, neutrophilic leukocytosos, monocytosis, absence of clinical signs of hemmorrhage, hyperbilirubinemia if destrution of sufficient magnitude
Why are neutrophillic monocytosis and leukocytosis seen in hemolytic anemia?
Leukocytes and monocytes are phagocytes and are called upon to eat the red blood cells.
When is hyperbilirubinemia seen in cases of hemolytic anemia?
Hyperbilirubinemia is seen if the destruction of RBCs is of sufficient magnitude to exceed the congugating capacity of the liver, of sufficient duration for biliruben to be formed, and bilirubin formation is sufficient.
Define hyperbilirubenemia.
presence of abnormal levels of bilireuben in the blood - ie icterus
What is the key feature of intravascular hemolysis?
heoglobinemia
Define hemoglobinuria.
the presence of hemoglobin in the urine
Define hemoglobinemia.
presence of abnormal levels of hemoglobin in the blood
What are the characteristics of anemia resulting from intravascular hemolysis?
most cases peracute or acute, regenerative response may not be evident (2-3 days required), and hemoglobinemia is present
What findings are seen in hemoglobinemia?
increased MCHC, red discoloration of plasma, hemoglobinuria
How do you identify the specific cause of an intravascular hemolytic anemia?
case history, labratory findings
What incidents in the patient’s history might cause an intravascular hemolytic anemia?
exposure to causative drugs/plants, recent transfusion of incompatable blood, neonatal exposure to colostrum
When should neonatal exposure to colostrum be suspected in cases of intravascular hemolytic anemia?
a weak, anemic foal or weak anemic calf born to a cow recently vaccinated with a blood origin vaccine
What lab procedures can assist in identifying the cause of a hemolytic anemia?
blood smear, Coomb’s antiglobulin test, antibody titer/cultures
What findings on a blood smear can indicate the cause of a hemolytic anemia?
Heinz bodies, RBC parasites
What does the direct Coomb’s test check for?
The direct Coomb’s test checks for the presence of antibodies on surface of RBCs.
What are the characteristics of anemia resulting from RE phagocytosis of erithrocytes (extravascuar hemolyisis)
usually chronic, regenerative response present, hemoglobin not evident in plasma or urine, hyperbiirubinemia usually does not occur
What can assist in the identification of the specific cause of an exrravascular hemolytic anemia?
patient history, lab procedures
What patient history suggests hereditary causes of extravascular hemolytic anemia?
history of particular breed and/or affected littermates
What lab prcedures are useful in detecting the cause of an extravascular hemolytic anemia?
blood smear, direct Coomb’s on patient RBCs, antibody titers, Coggins test
How is reduced or defective erythropoiesis diagnosed?
via bone marrow exam
What are the two types of reduced/defective erythropoiesis?
hypoproliferative and hyperproliferative with abnormal maturation
What are the presumptive findings for reduced or defective erythropoiesis?
nonregenerative anemia, chronic clinical course/slow onset, bone marrow abnormalities, neutropenia and thrombocytopenia concomitant with certian hypoprolierative types
Define neutropenia.
a lack of neutrophils in the blood
Define thrombocytopenia.
a lack of thrombocytes in the blood
What are the causes of anemia characterized by defective erythropoiesis?
chronic renal disease or endocrine disorders
What is the mechanism of anemia of chronic inflammatory or neoplastic disease?
diversion of iron to storage pool - not available for RBCs
What causes the recovery of patients with anemia caused by chronic inflammitory or neoplastic diseases?
alleviation of the primary disease
What clinical findings are seen in cases of anemia of chronic inflammatory or neoplastic disease?
low serum iron, anemia is usually moderate and nonprogressive
What findings suggest a problem at the stem cell level?
granulopoietic hypoplasia - neutropenia and associated erythroid hypoplasia
What lab findings are seen in cases of aplastic anemia?
cytotoxic effects, pancytopenia, bone marrow particles are small, acellular and fatty
What mechanism cause cytotoxic effects in cases of aplastic anemia?
chemical or radiation damage to the stem cells
Define pancytopenia.
abnormal lack of all blood cells
Why does leukopenia and thrombocytopenia usually precede anemia in cases of aplastic anemia?
Leukocytes and thrombocytes have a shorter life span then erythrocytes.
What is the mechanism of myelophthisic anemia?
physical replacement of bone marrow by an abnormal proliferation of cells (neoplasia) neoplastic cells may or may not (ex. myelofibrosis) be aspirated
Why may myelophthisic anemia present as a regenerative anemia in the early stages?
In the early stages there may still be a viable foci of hematopoiesis
What labratory findings are seen in cases of parvovirus and panleukopenia?
decreased platelets; decreased RBCs (late finding)
What laboratory findings are seen in cases of erlichiosis?
pancytopenia
What laboratory findings are seen in cases of FeLV associated panleukopenia syndrome?
decreased WBCs and RBCs
What are the possible causes of an anemia due to increased and/or abnormal granulocytopoiesis associated with erythroid hypoplasia (very high M:E ratio)?
granulocytic leukemia, panleukopenia in the recovery stage, impaired heme synthesis
What are the causes of impaired heme synthesis in cases of anemia due to increased/abnormal granulocytopoiesis associated with erythroid hypoplasia?
iron deficiency, pyridoxine defficiency, copper deficiency, anemia of lead poisoning
What are some causes of iron deficiency in cases of anemia due to increased/abnormal granulocytopoiesis associated with erythroid hypoplasia?
hemorrhage, dietary deficiency
What group of animals is particularly prone to iron deficiency anemia?
baby pigs, especially those kept on concrete
What characteristics are seen in anemia of lead poisoning?
anemia is mild or absent, increased NRBCs
When is abnormal maturation of the erythroid series seen?
erythremic myelosis and erythroleukemia
What finding on a blood smear is indicative of lead poisoning?
basophillic stippling
