Hematology exam 1
Transferrin
Iron transport protein that moves iron from sites of absoption
How to calculate Marrow cellularity
is estimated by subtracting age from 100%.
Eosinophils primary function
kill parasites
Polychromatic normoblast
last stage at which the cell is capable of undergoing mitosis
The breakdown products of heme go through several biochemical degradations to form:
Bilirubin
hemopexin
Binds free plasma heme
Hematocrit
%
RDW
%
MCH calculation
(Hgb x 10)/RBC units pg
MCHC calculation
(Hgb x 100)/Hct units d/dL or %
calculation for coefficient of variation (CV)
(SD/mean) × 100
describe the normal outcomes for .hematopoietic stem cell (HSCs) ?
- Differentiation into myeloid or lymphoid progenitor - Apoptosis due to lack of appropriate cell signaling stimuli - Self-renewal and continuation of the storage pool
Compared with manual methods, automated reticulocyte counting improved which concept?
- Distribution error - Statistical sampling error - Interobserver error This has resulted in an improvement in precision and accuracy.
Which erythrocyte activity requires energy?
- Energy is required to protect proteins in the red cell from oxidative damage. This includes hemoglobin and membrane proteins. - It is not required for oxygen transport, carbon dioxide exchange, or glucose transport into the cell.
heme is composed of
- Ferrochelatase, the final enzyme of the heme synthesis pathway, binds iron into the protoporphyrin IX ring, - Zinc protoporphyrin (ZPP) accumulates in red blood cells when iron is not incorporated into heme and zinc binds instead to protoporphyrin IX.
Erythropoietin increases the number of red cells by all of the following mechanisms:
- Increasing the rate of hemoglobin synthesis - Shortening cell division times - Allowing earlier cell egress from the bone marrow
medical laboratory scientist
- Responsible for ensuring the integrity of a specimen before analysis. - Only he or she can judge whether the specimen is acceptable so that valid results can be obtained.
The normal range of platelets in the peripheral blood circulation is:
150 - 450 x 10^3/uL
within +/- 1 std
68.2%
within +/- 2 std
95.4%
within +/- 3 std
99.7%
Specificity calculation
= TN / [TN + FP] x 100; reported as %
Sensitivity calculation
= TP / [TP + FN] x 100; reported as %
Having swollen lymph nodes is called:
Adentitis - is infection or inflammation of the lymph node.
Where is iron in the body located?
Approximately 70% of total body iron is found in hemoglobin. Almost 20% of body iron is in storage, mostly within hepatocytes and macrophages in the spleen and bone marrow. The remaining approximately10% is divided among the muscles, the cytochromes, various iron-containing enzymes, and the plasma.
When compared with mature erythrocytes, reticulocytes:
Are larger and bluer on Wright stain from remnant ribonucleic acid (RNA)
Which provides a negative feedback for heme synthesis, thus helping to control, by decreasing, its synthesis?
As the concentration of heme increases in the developing RBC; it acts as a negative feedback to decrease further synthesis of heme. This helps control its rate of production.
A patient's blood film had marked (3+) echinocytes and many broken (smudged) neutrophils. The same patient's blood film the day before did not show these features. Select the best course of action.
Confirm that the smear was made within 4 hours of specimen collection
when the cells are phagocytized with subsequent degradation of cell organelles.
Culling
Pronormoblast
First morphologically identifiable RBC precusor
Basophilic normoblast
First stage that detectable hemoglobin synthesis occurs
Intravascular hemolysis refers to the process of:
Fragmentation or destruction of red blood cells within the blood vessels
The cytokine G-CSF targets what cell line?
Granulocytes
Which of the following is not a component of lymph node structure?
Hassall's corpuscle (found in the thymus)
The A1c-modified component of Hb A is increased in what condition?
Hb A1c is a posttranslational modification of hemoglobin in which the hemoglobin molecule is glycated. Its concentration is increased when diabetes is uncontrolled.
Rule of three
Hct = Hb x 3 + & - 3%
Red blood cells are filled with _________________, a protein with the primary function of transporting __________________ to the body's tissues.
Hemoglobin, oxygen
Select the metabolic pathway that converts toxic hydrogen peroxide produced by oxidant drugs to water:
Hexose monophosphate pathway
What makes a better confirmatory test?
Higher specificity
Shift
If all results are consistently different from the previous in the same direction
Why does Hb F have a higher oxygen affinity than adult hemoglobin?
It is necessary to allow the fetus to extract blood from the maternal blood supply
The MCV on a patient is calculated to be 115 fL and the MCHC is 35 g/dL. What, in general terms, must be true of the MCH if it is consistent with the previous two indices?
It should be above reference range
The serum ferritin is used more often than bone marrow or liver biopsies to assess iron stores because it is:
Less invasive
Which is a characteristic of lymphatic fluid?
Low protein and the absence of RBCs.
Hypochromic
MCHC below reference range
normochromic
MCHC within reference range
Macrocytic
MCV above reference range
microcytic
MCV below reference range
Normocytic
MCV within reference range
What is responsible for erythrocyte deformability and maintaining cell shape?
Membrane proteins
Select the form of hemoglobin that contains iron in the ferric rather than the ferrous state.
Methemoglobin contains iron in the ferric form. This is nonfunctional hemoglobin (i.e., it cannot bind and carry oxygen).
What is the earliest morphologically identifiable cell in the granulocyte maturation sequence?
Myeloblast
A cell having a round nucleus with delicate chromatin, two to four prominent nucleoli, and a high N:C ratio of 8:1 with scant basophilic cytoplasm is an accurate description of a:
Myeloblast - is agranular (without any visible granules
What is the earliest stage of maturation where a neutrophil can be morphologically distinguished from an eosinophil?
Myelocyte
Which is true of megakaryocytes as they mature?
Nucleus become polyploid
Which of the following can be evaluated only through the microscopic examination of a stained blood film?
Presence or absence of cytoplasmic inclusions - These inclusions are important for cell identification and, when abnormal inclusions are present, sometimes provide "clues" as to the cause of disease.
What pools of neutrophils are included in the marginal neutrophil pool (MNP)?
Only cells loosely localized to the vessel walls
Hephaestin
Oxidizes iron as it exits the enterocyte
The enzymatic contents of primary (azurophilic) granules include:
Primary granules (found in developing myeloid cells) have the following contents: myeloperoxidase, acid beta-glycerphosphatase, cathepsins, defensins, elastase, and proteinase-3 (among others). Myeloperoxidase (MPO) in particular is a key component used to positively identify cell lineage, and a deficiency of MPO a disorder which leads to dysfunction in granulocytes.
Fettitin
Primary storage molecule for iron
Hepcidin
Production is increased in excess iron states
Apoptosis is:
Programmed cell death, which is a normal physiologic process eliminating unwanted, abnormal, or harmful cells.
Proper specimen collection and patient satisfaction are components of:
Quality assurance - encompasses everything from the test order by the physician to the reporting of results to the correct patient chart.
How can the correct platelet count on a patient be determined when his or her platelets repeatedly clump in an EDTA specimen?
Recollect in a sodium citrate (blue top) tube and multiply by 1.1
Where is heme produced?
Red blood cell (RBC) precursors in the bone marrow
All can be determined from a blood film EXCEPT:
Red cell estimate (count)
Manual cell counting methods in automated hematology laboratories are used for all of the following except:
Routine testing
Haptoglobin performs which function when red blood cells are lysed in circulation?
Salvage hemoglobin
How do sickle cells or spherocytes interfere with the ESR?
Sickle cells and spherocytes do not readily stack like normal RBCs, making the overall ESR result falsely decreased.
Which is true regarding carboxyhemoglobin?
Smokers have increased levels
Which occurs if testing is not performed within 24 hours of specimen collection?
Specific problems with older samples include WBC fragility and loss, swelling (which increases the MCV) and possible lysis of RBCs, and the deterioration of platelets.
Orthochromic normoblast
Stage at which the nucleus is ejected from the cell
The thymus is responsible for the initial development of:
T cells
leukopenia
a low total white blood cell count
Which regulatory standards mandate the concept of "test site neutrality" for all laboratory procedures?
The Clinical Laboratory Improvement Amendments (CLIA) requires test site neutrality, which means that all testing sites must follow the same regulatory requirements based on the complexity of the test method. Functionally, this means that you do not have different standards for point-of-care testing than for the same test performed in the main laboratory. OSHA sets standards for safety in the workplace. Joint Commissions and CAP are accrediting agencies.
Which can cause a falsely increased ESR?
The ESR tube must be kept at the absolute perpendicular to obtain a valid ESR result. Even only a slight tilt of the pipette (tube) causes the ESR to increase.
Which of the following parameters is always calculated (as opposed to being directly measured) by automated cell counters?
The MCHC is calculated from the HGB and HCT values.
The precision limits of a method are defined by:
The SD
absolute reticulocyte count calculation
The absolute reticulocyte count is = relative % reticulocytes × the red count.
Which is true for the relative affinity of hemoglobin for oxygen in the lungs and tissue with the oxygen dissociation curve in its normal position?
The affinity of hemoglobin for oxygen is high in the lungs, so that loading of hemoglobin with oxygen is facilitated. It is lower in tissue to facilitate the delivery of oxygen to tissue.
Erythrocyte
The final most mature form of RBC
Why is the mature erythrocyte unable to synthesize proteins or lipids?
The mature red cell lacks a nucleus, mitochondria, and other organelles. It is therefore unable to synthesize proteins or lipids. - It also cannot perform oxidative phosphorylation.
The average results of a method are defined by:
The mean
Reticulocytes demonstrate the characteristic polychromatic coloring when stained with Wright-Giemsa stain because of:
The presence of residual RNA/ribosomes
Why is the bone marrow (storage) pool of granulocytes so large compared with the total number found in peripheral blood?
They can be quickly released when needed to fight bacterial infection
Which of the following best describes the normal morphology of platelets on a peripheral blood smear?
They have irregular contours and are granular
Why is heme located inside a globin chain pocket surrounded by hydrophobic amino acids?
This arrangement helps keep iron in the divalent (ferrous) form regardless of whether or not it is carrying oxygen. This is critical for hemoglobin's ability to reversibly bind oxygen.
The proper term for a decrease in the number of platelets in circulation is:
Thrombocytopenia
The purpose of the receiver operator characteristic (ROC) curve is:
To determine the best cutoff point for discrimination of positive/negative values for an assay
What components of the erythrocyte membrane are responsible for its negative charge and are also blood group antigens?
Transmembrane proteins - include the glycophorins, which give the red cell its overall negative charge
What is the fate of erythrocytes when anaerobic metabolic enzymes are reduced in concentration or are absent?
When metabolic enzymes in the anaerobic pathway of glycolysis are reduced or absent, energy production in the form ATP is diminished. This ultimately results in hemolysis of the RBC because the functions requiring energy in the form of ATP are not fully operational.
external quality assessment
When results are compared with those of another laboratory
Intravascular means:
Within the blood vessels
necrosis
accidental death because of trauma
a complex interaction of plasma electrolytes, proteins, and carbon dioxide participates in:
acid-base balance.
Leukocytosis
an increase in white blood cell count
Upon centrifugation of a blood specimen, the layer between the red blood cells and plasma is called the:
buffy coat - This layer consists of both white blood cells and platelets.
How to calculate percent transferrin saturation
by dividing the serum iron by TIBC and multiplying by 100.
How can shifts occur?
can occur when a new reagent is introduced.
Leukemia
cancer of the blood cells, most often white blood cells
Red cells (i.e., hemoglobin)
carry oxygen to tissues
WBC count
cells x 10^3/uL
RBC count
cells x 10^6/uL
What stimulates production of erythropoietin?
decreased oxygen level in tissue
White cells
defend against bacterial invasion
MCV
fL
Membrane lipids
form the fluid foundation into which the membrane proteins are inserted.
Peripheral proteins
form the skeletal network of the red cell membrane
Hemoglobin
g/dL
Random errors
happens only infrequently and is not predictable.
hematocrit
he packed cell volume that reflects the number of red blood cells.
MCV calculation
hematocrit x 10 / # of red blood cells in sample units fL
parameter that are directly measured
hemoglobin concentration via cell lysis and subsequent spectrophotometry, and the WBC and PLT counts being measured by either electrical impedance or optical light scatter methods (depending on the instrument).
Reliability
how well a method maintains both accuracy and precision over time.
A stained blood film is held up to the light and observed to be bluer than normal. What microscopic abnormality might be expected on this film?
increased protein levels in the blood; increased immunoglobulin production (protein) or increases in some other plasma proteins (like fibrinogen) --> Rouleaux
basophils
initiators of the allergic response.
Neutropenia
low cell count that is specific to the neutrophils
Cation pumps
maintain the Na+ and K+ gradient within the red cell.
Ca2+ pump
maintains intracellular levels of Ca2+.
plasma cells (fully differentiated B cells)
make antibodies
MCH
pg
What important function does 2,3-BPG perform?
plays a critical role in the effective transport of oxygen to tissue. It is produced via a shunt off the EMP. Elevations in 2,3-BPG are seen in a number of situations such as anemia; they result in more effective delivery of oxygen to tissue.
corrected reticulocyte count calculation
reticulocyte % × patient's hematocrit/"normal" hematocrit - "normalizes" the hematocrit to 45%.
Haptoglobin
salvage molecules for free hemoglobin in the plasma
Trend
show a gradual change over time
Iron overload and iron toxicity
situations in which the percent saturation would be high/increased.
Which of the following is NOT a function of the spleen?
support megakaryocyte differentiation or platelet production directly.
serum
the liquid portion of the blood formed from a clotted blood sample.
Sensitivity (diagnostic)
the probability that a person with a given disease will be correctly identified as having it by a clinical test
Acceptable criteria include
type of specimen for the test ordered (e.g., blood, serum, urine); appropriate additive present (if needed) and amount of specimen relative to the additive; time interval since obtained; and presence or absence of hemolysis, lipemia, and other similar conditions.
Standards
used to calibrate instruments.
Controls
used to routinely evaluate the accuracy of a method once it is calibrated.
What are the function of macrophages in the bone marrow?
- Secreting cytokines - Storing iron - Phagocytizing senescent bone marrow cells
Which is most responsible for the strength and pliancy of the red cell membrane?
- Spectrin composes the majority of the membrane's skeletal mass and is the primary peripheral protein involved in maintaining the skeletal structure of the red cell. - plays an important role in making the red cell membrane deformable (pliant). This flexibility is important for permitting the red cell to "squeeze" through pores that have a diameter smaller than that of the red cell.
What organs normally involved in hematopoiesis at any stage of fetal development?
- The bone marrow is the primary site of hematopoiesis from the 3rd trimester of fetal development forward through adulthood. - The liver and spleen both play roles in blood cell development, particularly during fetal development and as minor sites of blood cell development even in adults.
Which is true of red cell precursors as they mature?
- basophilia decreases as the red cell matures (one exception to this: the basophilic normoblast is characteristically more basophilic than its precursor, the pronormoblast). - The nuclear-to-cytoplasmic ratio actually decreases, the cells become smaller - nucleoli become less prominent and eventually disappear.
delta checks
- compare a patient result with a previous result (same test on the same patient). - This can only be done for a test result that essentially does not vary significantly from testing time to testing time.
Proportional systematic
- in which the magnitude varies relative to the result.
A cell that is actively synthesizing protein has:
- more nucleoli, less heterochromatin (and more euchromatin), and more mitochondria and ribosomes. - This is typical of less mature hematopoietic cells, like developing RBC and WBC precursors.
reference ranges
- should be determined by evaluating a group of perhaps as many as 120 normal healthy people for the same analyte. - If the analyte differs in different groups, based on data such as age and sex, it must be determined for each group if at all possible.
Inaccurate results
- significantly different (~25% difference between the two results). - not accurate results can not be reported
platelet pellet
- special layer of platelets that is required for platelet function studies. - This layer of platelets is prepared from a whole blood specimen using specific centrifugation time and speed.
Precision
- the ability to reproduce a result on the same specimen. - multiple results are needed to determine - determined using same instrument
acute infection
- the anemia of chronic inflammation (also called anemia of chronic disease) might develop if the infection becomes chronic. - Percent saturation would be decreased below normal, but it would not become this low (and the infection would have to be fairly long-standing and chronic).
Specific (diagnostic)
- the probability that a person who does not have a disease will be correctly identified as not having it by a clinical test - how well it identifies only positive patients.
How can trends occur?
A fading light source
Reticulocyte count calculation
A total of 1000 red cells plus reticulocytes are always counted (and thus 1000 is the denominator when performing a reticulocyte count).
Lymphocyte concentrations in peripheral blood are highest during what age interval?
Absolute lymphocyte counts (ALC) can range up to ~14,000/uL in infants in the first few days of life, but tend to drop off slightly and resurge around 1 year of life. The ALC will slowly decline from around age 3 to assume normal adult levels in the early teens.
What is the mechanism for iron toxicity if iron is present in excess amounts?
Acts as a catylyst in forming hydroxyl (free) radicals
A patient peripheral blood film demonstrates agglutinated RBCs, and the CBC shows an elevated MCHC. What other parameters will be affected by the agglutination of the RBCs?
Agglutination is an antigen-antibody reaction which causes RBCs to become stuck together. This will spuriously decrease the RBC count which leads to an increased MCHC. The hemoglobin is typically unaffected, the RDW may be increased, and the platelet count may be normal or decreased. The MCV is typically increased as a result of multiple cells being measured at the same time.
The primary lymphoid organs are the:
All lymphocytes develop initially in the bone marrow. Lymphoid progenitor cells migrate to the thymus for antigen-independent and antigen-dependent phases of maturation, eventually producing T cells. B cells go through antigen-independent maturation phases in the bone marrow and then migrate to the secondary lymphoid organs for antigen-dependent maturation. Secondary lymphoid organs include the spleen, lymph nodes, tonsils, and MALT (mucosa-associated lymphoid tissues). The bone marrow and thymus are considered the central or primary lymphatic/lymphoid organs.
Acute (24-hour) assessment of the amount of iron that is available for hemoglobin production is best identified by measuring the:
Amount of hemoglobin in reticulocytes
The principle energy source for mature red blood cells (RBCs) is:
Anaerobic glycolysis is the pathway by which glucose is metabolized in the red cell, and ATP is generated through this pathway.
The antinuclear antibody (ANA) test is positive in almost all people who have systemic lupus erythematosus (SLE). It is also positive in some patients who do not have SLE. The anti-deoxyribonucleic acid (anti-DNA) test is positive only in people with SLE but not in all who do. Which of the following is true? The ANA test is a good screening test, and anti-DNA test is a good confirmatory test
Because almost all patients with SLE have a positive ANA test, it is a good screening test (if the result is negative, it practically rules out this diagnosis for a patient). However, because the ANA test is also positive in other patients, the anti-DNA test is a good confirmatory test, because only patients with SLE have a positive result. In practice, the ANA test is done first; if it is positive, then the anti-DNA test is done as follow-up. If a patient is positive with both tests, then his or her diagnosis is SLE.
After birth, where does hematopoiesis predominantly occur?
Bone marrow
The following is unique to both B and T lymphocytes and occurs during their early development:
Both B and T lymphocytes undergo gene rearrangement for antigen receptors. B and T cells are capable of rearranging antigen receptor gene segments to produce a wide variety of antibodies and surface receptors.
Cellular movement toward or away from a chemical stimulus is called:
Chemotaxis
Which group of patients should not be included in establishing moving averages using red cell indices?
Chemotherapy patients
As cells mature, they typically:
Decrease in size
Soluble transferrin receptor (sTfR) levels increase when intracellular iron levels are:
Decreased
Platelet satellitosis is most likely to cause which of the following spurious CBC results?
Decreased platelet count
Counting the number and size of electrical interferences created by blood cells as they pass through a small aperture is a description of which principle?
Electronic impedance
Which is the metabolic pathway that generates a net gain of two molecules of ATP for erythrocyte energy needs?
Embden-Meyerhof pathway (anaerobic glycolysis)
Response to parasitic infections is associated with an increase of which type of granulocyte?
Eosinophils
When hematopoiesis occurs in the liver in an adult, it is called: this is adnormal
Extramedullary
The primary function of platelets is to:
Facilitate blood clotting
Which of the following is NOT an advantage of using "quick" Wright or Wright-Giemsa stains?
Improved quality; quick stains produce better results than other staining methods
Macroscopic holes in a blood film most likely mean the patient has:
Increased lipids in the plasma can cause the appearance of holes all over the blood film.
Which stains blue with Prussian blue stain?
Only the insoluble form of storage iron, which is hemosiderin, stains
Which has a pyknotic nucleus? - meaning that the chromatin is fully condensed.
Orthochromic normoblast - After this stage, the cell no longer needs the nucleus and it is extruded or expelled.
How is erythropoietins produced?
Peritubular cells in the kidney detect an undersupply of oxygen in tissue (also called hypoxia). They then synthesize erythropoietin. This increases red cell production in the bone marrow, unless the marrow is unable to respond the erythropoietin stimulus.
Neutrophils primary function
Phagocytize bacteria
Which splenic process removes inclusions from circulating red blood cells?
Pitting
Which cells are responsible for antibody production?
Plasma cells
Diagnostic testing at or near the site of patient care is known as:
Point-of-care testing
Endomitosis is a form of mitosis that lacks telophase and cytokinesis and which results in cells that are:
Polyploidy refers to the condition in which a normally diploid cell or organism acquires one or more additional sets of chromosomes.
Ferroportin
Transport protein that facilitates iron transport one way out of the cell
Which correctly describes the structure of normal hemoglobin A (Hb A)?
Two alpha and two beta polypeptide chains, each containing one heme group
Forward angle light scatter, when used in an instrument using the optical scatter principle, correlates with cell:
Volume (size)
Platelet clumps would most likely interfere with which other automated parameter?
WBC count
All will be invalid when significant lipemia is present in a blood sample except:
When a blood sample is lipemic, the hemoglobin is falsely elevated. The MCH and MCHC are also falsely elevated because they use the hemoglobin measurement for their calculation. The MCV is valid because it does not depend on the hemoglobin measurement.
MCHC
g/dL or %
Quality control
involves running control samples using the same methodology as for the patient specimens.
2,3-biphosphoglycterate (2,3-BPG) production
is a shunt off of the EMP that is important for the reversible binding of oxygen.
Glucose-6-phosphate dehydrogenase (G6PD) is:
is an enzyme in the hexose monophosphate pathway and is important for maintaining reduced glutathione in the red cell. - This pathway does not produce any energy and has no function in carbon dioxide transport.
Methemoglobin reductase
is an enzyme that reduces the oxidized form of hemoglobin, called methemoglobin, to its reduced functional form.
reduced glutathione
is critical for preventing oxidative damage to red cell proteins.
Internal quality assessment
is done totally within one laboratory
constant systematic
is one in which the magnitude of the error remains the same throughout the range of the test measurement.
The hexose monophosphate pathway, through which aerobic glycolysis occurs
is the pathway that generates reduced glutathione. Reduced glutathione is essential to prevent oxidant injury to the red cell.
Platelet satellitosis
is the phenomenon where platelets are observed surrounding or adhering to WBCs.
Which is true of hemoglobin if the oxygen dissociation curve shifts to the left?
it will load oxygen more easily in the lungs but also will hold onto it more tightly in tissue, thus delivering less oxygen to tissue. - example of high oxygen affinity. - Hemoglobin F
Erythropoietin is a growth factor affecting erythroid progenitors and is produced by what organ?
kidney when it senses hypoxia
Meat
source of heme iron
legumes and fortified flour
source of nonheme iron
Reticulocyte
stage at which red blood cells normally leave the bone marrow and enter peripheral circulation
Extravascular hemolysis occurs when:
this refers to the splenic function of culling RBCs via macrophage phagocytosis.
