Unit 3 Flashcards
Anemia is considered to be present if:
- the Hb concentration of the RBCs or the Hct is below the lower limit of the reference range for the individual’s age, gender, and geographical location.
Define anemia
A decrease in the ability of RBCs to carry oxygen to the tissues resulting in hypoxia
Anemia may be a sign of an underlying disorder such as:
- liver disease
- alcohol toxicity
- hypothryroidism
- myelodysplasia
What is the development of anemia related to?
- normal erythrocyte kinetics
Describe how anemia is related to normal erythrocyte kinetics
- the total RBC mass in a daily steady state is the balancing of the number of new erythrocytes produced each day to replace the RBCs that have reached the end of the their life span of 120 days
What can the clinical signs and symptoms of anemia result from?
- Diminished delivery of oxygen to the tissues
- related to the lowered Hb concentration
- clinical signs reflect the rate of reduction of Hb and blood volume
What are common signs and symptoms of anemia
?
- fatigue
- shortness of breath
- skin pallor
- not as common: vertigo, faintness, headache, and heart palpitations
How are anemias classified based on red cell morphology?
- categorizes anemias by the size of the erythrocyte
- Macrocytic, microcytic, normocytic
How are anemia classified based on pathophyslogically?
- Impaired RBC production: insufficient or ineffective erythropoiesis
- Increased RBC destruction: hemolysis
- Blood loss (acute or chronic)
Describe factors that impact HSC or development issues
- aplastic anemia
- myelodysplastic anemia
- malignant metastases
- Acquired—> acute hemorrhage
- inherited —> chronic hemorrhaging
Describe what causes bone marrow damage
- chemicals, radiation
- some drugs
- iron deficiency and thalassemia
Blood loss: RBC membrane defect or enzyme deficiency
Describe infiltration of bone marrow
- Neoplasms
- abnormal Hb molecule
Describe nuclear defect of impaired red cells
- megaloblastic anemia
- blood loss: Antibody reaction, infectious microorganisms, chemical/ drug reaction, and traumatic cell injury
Describe semiquantitative grading of erythrocyte morphology
- erythrocyte changes are commonly reported using the following:
—> descriptive terms, such as few, moderate, or marked
—> grades on a numerical scale such as: 1+, 2+, 3+ …
—> 1+ = slight to few
—> 2+ = moderate
—> 3+/4+ = marked
Describe laboratory assessment of Anemia
- Clinical signs and symptoms
- CBC wire differential, RBC indices and morphology, reticulocyte count
- Hb decreased: males = <13.0 g/dL and females <12 g/dL
- Classification by RBC indices
What would it mean if the patient has low MCV, low MCHC, is microcytic and hypochromic?
- typical of matural defects:
- iron deficiency anemia
- Thalassemia
- Sideroblastic anemia
What would it mean if the patient has Normal MCH, normal MCHC, is normocytic and normochromic?
- typical of hypoproliferation
- Bone marrow disorder
- iron deficiency anemia
- autoimmune disease
What would it mean if the patient had High MCV or macrocytic?
- typical of maturation defects
- Vitamin B12 deficiency
- folate deficiency
- excessive alcohol ingestion
- hypothyroidism
What are additional assessments of anemia?
- RBC indices
- The red cell histogram
- Red cell distribution width (RDW) or red cell morphology index (RCMI)
- PB smear evaluation
- Reticulocyte count
- BM examination
What is the supplementary testing for Normal MCH and MCHC?
- serum iron
- Total iron-binding capacity (TIBC)
- Ferritin
What supplementary testing is performed on decrease MCV and MCHC?
- Serum ion
- total-iron binding capacity (TIBC)
- ferritin
What supplementary testing is performed when MCV is increased?
- serum vitamin B12
- Serum folic acid
Describe bone marrow examination for anemias
- may be performed if properly indicated and may reveal an abnormal ratio of leukocytes to erythrocytes using the myeloid:erythroid (M:E) ratio
Describe Hb F concentration testing of anemia
To evaluate possible hemoglobinopathies and thalassemias
Describe thick and thin smear assessment for anemia
- to evaluate the presence of possible material or Babesial parasites
Describe platelet count for assessment of anemia
To evaluate healing sufficiency after trauma
Describe reticulocyte count of anemia assessment
To evaluate red cell production in the bone marrow (can help ID pathophysioloic mechanisms of anemia)
Describe Sickle Cell testing for anemia assessment
- to screen for sickling hemoglobinopathies
Describe G6PD assay of anemia assessment
To screen for enzyme deficiencies in G6PD enzyme activity
Describe hemoglobin electrophoresis
- to separate out Hb protein fractions to identify possible hemoglobinopathies and thalassemias
What tests are performed in other parts of the lab that could be useful?`
- antibody screening and ID tests
- Direct antiglobulin (AHG) test
- Measurements of bilirubin levels
- Folic acid or vitamin B12 assays
What is the purpose of antibody screening and ID tests?
- to identify immune causes of RBC destruction
What is the purpose of the Direct antiglobulin (AHG) test?
To screen for immune causes of RBC destruction
What is the purpose of measuring bilirubin levels?
To help identify RBC destruction (either intracvacular or extravascular)
What is the purpose of folic acid or vitamin B12 assays?
To help identify megaloblastic anemia due to nutritional deficiencies in folate and B12 vitamins
What is the purpose of haptoglobulin level testing?
- to help identify intravascular hemolysis
What is the purpose of lactic dehydrogenase (LDH) determination ?
To help identify intravascular hemolysis
What is the purpose of Serum iron and total binding capacity?
- to measure circulating iron in the serum and transferrins binding capacity for iron
What is the purpose of occult blood testing?
To identify GI bleeds as a source of chronic blood loss
What is the purpose of Urbilinogen screening ?
To identify hemolysis in general, does not distinguish between intravascular and extra vascular
What are indications for a bone marrow evaluation?
- microcytic anemia where iron storage assessment with Prussian blue stain may be a value in anemias of chronic disorders or the presence of sideroblasts in sideroblastic anemia
- normocytic or macrocytic anemia without increased retic production to evaluate or myelodysplasia
- Neutropenia, thrombocytopenia or pancytopenia without an explaination
- immunoglobulin disorders such as multiple myeloma
- Neoplasms such as acute leukemia or lymphomas for diagnosis and/or staging purposes
What occurs if the survival time of RBCs is decreased?
- bone marrow must increase production to maintain balance of the RBC mass (homeostasis)
What does increased erythropoiesis depend on?
Demonstrated by an increase retic. Count which is dependent on available iron and protein
What is absolute iron deficiency?
Inadequate utilization of iron stores
What is functional iron deficiency?
A condition where the total body iron is adequate, but it cannot be mobilized fast enough for needed increase in erythropoiesis
What is the limitation of classifying anemias?
Within each classification, the various subdivisions are not completely inclusive
Which mechanism for classifying anemia has more merit? Why?
Physiological system because it describes the basic mechanism or probable mechanism responsible for the anemia
What is the limitation of morphological classification?
- it tells nothing about they etiology or reason for the anemia
What conditions are associated with Macrocytic anemia
- seen in maturational defects and non-megaloblastic anemia
- Alcoholism
- Liver disease
- aplastic anemia
- Myelodysplastic syndrome
What is disorders are associated with accelerated erythropoiesis of nonmegaloblastic macrocytic anemias.
- hemolytic anemia
- posthemorrhagic anemia
What disorders are associated with pathological megaloblastic anemia?
- pernicious anemia
- folic acid deficiency
- myelodysplasia
- erythroleukemia
- some drugs
What is most likely cause of macrocytosis?
Folic acid deficiency
Describe hypoproliferative anemias
- have normal RBC size
- demonstrate a hypocellular bone marrow with a normal or increased myeloid:erythroid (M:E) ratio
How are normocytic anemia separated?
Based on erythrocyte response of bone marrow
Describe intrinsic hemolytic anemias
- increased Retic. Count
- membrane defects
- Hemoglobinopathies
- enzyme deficiencies
Describe extrinsic hemolytic anemia
- increased Retic. Count
- can be caused by immune reactions or non immune red blood injury such as infectious agents, drugs, chemicals, venoms, and severe burns
What are microcytic anemias associated with?
- defective hemoglobin synthesis
- include late stage iron deficiency anemia, anemia of chronic disorders, sideroblatic anemia, thalassemia and HbE disease trait
What is Hb and Hct measurements affected by ?
- altered plasma volumes
- chronic oxygenation status
- hemoglobin variations
- abnormal hemoglobins
The laboratory based definition of anemia is a reduced concenconcentration of of ______ compared to a reference value
- Hb or parked erythrocytes
What is a significant laboratory finding in anemia?
Decreased Hb
The reference range for MCV is?
80-96 fL
What is the reference range for MCH?
27-33 pg
What is the reference range for MCHC?
33-36%
Describe the etiology of blood loss anemia
- the acute loss of blood is usually associated with traumatic condtions such as an accident or severe injury
- occasionally acute blood loss may occur during or fate surgery
Describe physiology of acute blood loss anemia
- acute blood loss does not produce an immediate anemia
- a severe hemorrhage or rapid blood loss amounting to more than 20% of the circulating blood volume reduces an individual’s total blood volume and produces a condition of shock and related cardiovascular problems
- in acute blood loss, the body itself adjusts to the situation by expanding the circulatory volume, which produces the subsequent anemia
What is the etiology of acute vs chronic blood loss anemia?
Acute —> trauma
Chronic —> GI tract
Is there blood loss disruption in acute vs chronic blood loss anemia?
Acute—> yes
Chronic —> no
Is there iron deficiency in acute vs chronic blood loss anemia?
Acute —> no
Chronic —> yes
What is the Hct levels in acute vs chronic blood loss anemia?
Acute —> normal
Chronic —> decreased
What is the WBC count of acute vs chronic blood loss anemia?
Acute —> increased
Chronic —> Normal
What is the platelet levels of acute vs. chronic blood loss anemia?
Acute —> increased
Chronic —> Normal
What is the Reticulocyte levels of acute vs chronic blood loss anemia?
Acute —> Normal
Chronic —> Increased
Describe physiological adaptions to acute blood loss
- increased respiratory rate
- increased heart rate and cardiac output
- redirected blood flow from the periphery of the body to the vital body core, for example, heart and brain
Describe physiological adaptions to chronic blood loss
- increased erythropoietin production
- increased 2,3-DPG (BPG) production
- decreased hemoglobin-oxygen affinity
What is the earliest hematological change in acute blood loss?
- transient all in the platelet count, which may rise to elevated levels within 1 hour (inflammatory reaction)
After the fall in platelet count, what is the next hematological change in acute blood loss?
The development of neutrophilic leukocytosis (10-34 x 10^9/L) with a shift to to the left
Describe the Hb and Hct levels during acute blood loss anemia
- do not fall immediately but fall as tissue fluid moves into the blood circulation.
- It can be 48-72 hours after the hemorrhage until the full extent of the red cell loss is apparent
Describe the peripheral blood film of acute blood loss anemia at 24 hours
- NC/NC
- normal MCV, MCH, MCHC
Describe the peripheral blood film of acute blood loss anemia after 5 days
- increased reticulocyte which develops macrocytosis
- takes place 3-5 days after the blood loss and reaches a maximum at 10 days later
How long does it take the blood to recover from anemia such as WBC count, morphological picture, and red cell profile?
- it takes 2-4 days after blood loss for WBC count to return to normal
- about 2 weeks for morphology to disappear
- the return of red cell profile to previous values takes longer than 2 weeks
Describe when 500-1000 mL of blood loss occurs
- 10-20% blood volume
- few or no symptoms
Describe when 1,000-1,500 mL of blood loss occurs
- 20-30% blood volume
- symptoms: asymptomatic, light-headedness, hypotension, tachycardia
Describe when 1,500-2,000 mL of blood loss occurs
- 30-40 % blood volume
- thirst
- shortness of breath
- clouding or loss of consciousness
- blood pressure
- cardiac output
- venous pressure decrease
- pulse usually becomes rapid
- cold extremities
- clammy
- pale
Describe when 2,000-2,500 mL of blood loss occurs
- 40-50% blood volume
- lactic acidosis
- shock
- irreversible shock
- death
Describe etiology of chronic blood loss anemia
- frequently associated with disorders such as the following:
—> GI tract
—> Heacy menstruation in women
—> urinary tract abnormalities
Describe the bleed of chronic blood loss anemia
- blood loss of small amounts occurs over an extended period, usually months
- does not disrupt blood volume
Describe blood lost in seal amount over an extended period of time
-both the clinical and hematological features seen in acute bleeding are absent
- regeneration of RBCs occurs at slower rate
- the reticulocyte count may be normal or slightly increased
describe laboratory findings of Chronic blood loss anemia
- a noticeable anemia does not usually develop until after storage iron is depleted
- gradually, chronic bleeding results in an iron deficiency, and the newly formed cells are morphologically hypochromic and microcytic
- the WBC count is normal or slightly decreased
- Platelets are commonly increased, and only later, in severe iron deficiency, are they likely to be decreased
What is aplastic anemia
- one of a group of disorders, known as hypoproliferative disorder, that are characterized by reduced growth or production of blood cells
- unusual disease of bone marrow failure
What are diseases easily confused with aplastic anemia?
- fanconi’s anemia
- dyskeratosis congentia
- acquired
- aleukemic leukemia
- large granular lymphocytosis
- myelodysplasia
- myelofibrosis
- paroxysmal nocturnal hemoglobinemia
What are characteristics of fanconi’s anemia?
Expressed in young patients, physical anomalies
What are characteristics of dyskeratosis congenita?
Expressed in young patients, physical anomalties
What are the characteristics of aleukemic leukemia?
Very young or very old patients, blasts in Buffy coat and bone marrow spicules
What are characteristics of large granular lymphocytosis?
Older patients, neutropenia
What are characteristics of myelodysplasia?
Older patients, bone marrow has normal cellularity or hypercellular
What are characteristics of myelofibrosis
Heptaosplenomegaly, leuko-erythroblasts appearance on peripheral blood smear
What are the characteristics of Paroxysmal nocturnal hemoglobinemia (PNH)?
RBC hemolysis
What does cytopenia with hypocellular marrow impact?
- all three cell lines, resulting in pancytopenia as in constitutional aplastic anemia
- two cell lines such as PNH
- a single RBC, WBC, or PLT cell line such as Diamond-Blackfan anemia (DBA)
- can be due to premalignant conditions or myelofibrosis
What are laboratory findings in Bone marrow syndromes?
- wide range or mild to severe cytopenias
- macrocytosis can be seen and in some situation may be the only finding
—> some situations may be masked by an underlying iron deficiency or thalassemia - elevated Hb F is common
- dysplastic changes in cells of the marrow
What are the three types of aplastic anemia?
- Idiopathic aplastic anemia (major form)
- Iatrogenic aplastic anemia
- Constitutional aplastic anemia
Describe idiopathic aplastic anemia
- major form
- occurs in patients with no established history of chemical or drug exposure or viral infection
Describe constitutional aplastic anemia
- designates a congenital or genetic predisposition to bone marrow failure
What are iatrogenic agents?
- benzene and benzene derivatives
- trinitrotoluene
- insecticide’s and weed killers
- inorganic arsenic
- anti-metabolites
- antibiotics`
What are immune mediated causes of aplastic anemia?
- Iatrogenic agents
- transfusion-associated graft versus host disease
- eosinophilic fasciitis
- Hepatitis- associated disease
- pregnancy
- intermediate metabolites of some common drugs
- idiopathic aplastic anemia
Describe immune-mediated pathophysiology of aplastic anemia
- activated type 1 cytotoxic T cells implicated
- telomere repair gene mutations in the target cells and dysregulated T-cell activation pathways
- cellular immune suppression may occur transiently with certain viral infections, such as parvovirus virus or certain medications
Describe Hematopoietic failure pathophysiology of aplastic anemia
- insufficient or defective pluripotent stem cells, progenitor stem cells, or committed stem cells
- the microenvironment may be unable to provide for the normal development of hematopoietic cells
- absence of humoral or cellular cytokines (stimulators)
- excessive suppression of hematopoiesis by resident T lymphocytes or macrophages
What are signs and symptoms that depend on the degree of the deficiencies?
- bleeding from thrombocytopenia
- infection from neutropenia
- signs and symptoms of anemia
- splenomegaly and lymphadenopathy are absent
What are the phases of Aplastic Anemia?
- Onset of disease
- recovery
- late disease
What infections are responsible for causing aquired cases of APA?
- HBV
- HCV
- measles
- EBV
- cytomegalovirus
Define Iatrogenic
- relation to illness cause by medical examination or treatment (side effects that can lead to conditions)
What are examples of Iatrogenic agents?
- Benzene and benzene derivatives
- Trinitrotoluene
- Insecticides and weed killers
- Inorganic arsenic
- Antimetabolites
- Antibiotics
What is APA caused by?
- damage or destruction of the hemopoietic tissue of the bone marrow that results in deficient production of blood cells.
What is it called when all cell lines are affected?
Pancytopenia
When is a diagnosis of APA made?
When at least 2 of the 3 PB values fall below critical levels
Describe what the peripheral blood smear would look like in APA
- NC/NC
- varying degrees of anisocytosis and poik with normal RDW in most cases
Describe genetic influence of APA
TERT or TERC (5-10% of patients) teleomerase mutations found
Describe acute exposure to radiation of APA
- in the inciting agent, the production of new RBCs falls, but the RBCs decline slowly because of their long survival
- the first few hours, there is neutrophilic leukocytosis
- after first day, decrease in lymphocytes and is responsible for leukopenia
- after 5 days, granulocytes begin to decrease
- later, platelets decrease
Describe treatment for APA
- APA responds to immunosuppressive therapy, but success in treating this disease appears to be the degree of organ destruction, the capacity for tissue regeneration, and perhaps most importantly, a drug regimen that can control a misdirected and extraordinarily potent immune response
- can be cured by stem cell transplantation or immunosuppressive drug therapy
Describe the pathophysiology of Fanconi’s anemia
- best described congenital for of APA
- produced due to one or more mutations in the FAC gene
Describe laboratory finds of Fanconi’s Anemia
- it is characterized by a progressive pancytopenia over years
- diagnosis is usually made in children 5-10 years old.
- chromosome studies with the addition of diepoxybutane is the test of choice to ID FA. Increased chromosome breakage confirms the condition
What are clinical signs and symptoms of Fanconi’s anemia ?
- about 50% of patients show clinical abnormalities such as:
- short stature
- microcephaly
- malformed thumbs
- strabismus
- mental retardation
Describe etiology of Fanconi’s anemia
- inherited through an autosomal recessive mode with the exception of the FA-B subtype
What are test methods for Fanconis anemia?
- gold standard is demonstration of increased chromosomal breakage following exposure to clastogenes
Describe Dyskeratosis Congenita
- inherited BM failure syndrome
- characterized by the mucocutaneous triad of:
—> abnormal skin pigmentation
—> Nail dystrophy
—> Mucosal leukoplakia - BM failure accounts for a predisposition to malignancy and fatal pulmonary complications
Describe the etiology of Pure Red Cell Aplasia (PRCA)
- Acute (transient): parvovirus, other infections, drugs, riboflavin deficiency
- Acquired chronic: idiopathic, associated with thymoma and lymphoma
- congenital: Diamond-Blackfan syndrome
Describe Acute (transient) PRCA
- the more common diagnosis for a child
- affects young children under the age of 8, with most cases diagnosed between 1-3 years old.
- pretend by a history of viral infection within the past 3 months is frequent
- Self-limiting illness
- pathogenesis: humoral inhibition of erythropoiesis or decreased stem cells.
Describe acquired PRCA
- selective failure of RBC production
- rarely occurs in middle-aged adults
- approximately 50% are associated with thymomas
- reticulocytopenia and a cellular marrow devoid of all but primitive erythroid precursors
Describe chronic acquired PRCA
- associated with drugs, collagen vascular disorders and lymphoproliferative disorders
- also on the spectrum of autoimmune cytopenias with antibodies that target erythroid stem cells of normoblasts
What are signs and symptoms of Diamond-Blackfan anemia (DPA)
- proapoptotic hematopoiesis
- BM failure
- short stature
- birth defects
- cancer predisposition
What are other names for Diamond-Blackfan anemia?
- congenital pure red cell aplasia
- congenital hypoplastic anemia
Describe etiology of DBA
- congenital mutations in RPS19 and other genes encoding ribosomal proteins cause DBA
Describe pathophysiology of DBA
- total of 77 mutations have been described to date
- mutation target the protein production of either the 40s or 60s subunits
—> hypoproliferation of erythroid cells and the enhanced sensitivity of hematopoietic progenitors to apoptosis
—> defective maturation or ribosomal subunits delay translation of globin genes, which leads to erythroid-specific apoptosis and anemia
What are the classic diagnostic criteria for DBA/
- anemia appearing prior to the first birthday
- normal or slightly decreased neutrophil count
- variable platelet counts, often increased
- macrocytosis
- normal bone marrow cellularity with few red cells precursors
Describe treatment for DBA
- approximately 75% of patents respond at least partially to steroids
- the overall long-term survival rate is approximately 65%, although many patients require long-time steroid treatment