Hematology MCQ

Insufficient centrifugation does not pack down the red cells, therefore the Hct increases.

Electronic cells counters use the principle of electrical impedance. Two electrodes suspended in isotonic solutions are separated by a glass tube having a small aperture. A vacuum is applied and as a cell passes through the apertures it impedes the flow of current and generates a voltage pulse.

The manual reticulocyte count involves the counting of 100 RBCs. The Miller disk is a grid that is placed in the eyepiece of the microscope and divides the field into two squares. Reticulocytes are counted in both the squares and the mature red cells are counted in the smaller ones.

Pica is a clinical finding seen in some patients with iron deficiency. Pica is unusual cravings for nonfood items that may include dirt, clay, and laundry starch or most commonly ice. Among some cultures, pica is a custom that may contribute to iron deficiency. In children, lead poisoning often results from the ingestion of dirt or lead-based paint from toys and may be related to iron deficiency.

Idiopathic onset is an unknown cause of warm autoimmune hemolytic anemia (WAIHA). Secondary WAIHA is usually associated with chronic lymphoid disorders, viral infections, and autoimmune disorders.

CD4 and CD8 markers are monitored in patients with acquired immunodeficiency virus infection. CD33 and CD34 would more likely be used for investigating a suspected acute myeloid leukemia (AML) case.

The liver of foetus assumes responsibility for hematopoiesis about the second month of gestation. From 3 to 6 months of fetal development the spleen, thymus and lymph nodes are also involved, but the principle site of hematopoiesis remains the same(liver).By the seventh gestational month, the bone marrow become the primary hematopoietic site.

All cells experience the deterioration of their enzymes over time due to natural catabolism. Most cells are able to replenish needed enzymes and continue their cellular processes. As a non-nucleated cell, however the mature erythrocyte is unable to generate new proteins & enzymes so its cellular functions decline, the cell ultimately approaches death. RBC lack mitochondria, so rely on glycolysis for production of ATP.

A senescent red blood cells is one that has lived its life span. The red cells are removed from the circulation by splenic macrophages that recognize subtle abnormalities in these cells, sequester them and destroy them.

The amount of circulating ferritin indirectly reflects the amount of storage iron in the tissues. Serum ferritin is an acute phase protein produced, mostly by the liver, during the acute phase of inflammation, especially during infections. Therefore, the serum ferritin should be interpreted with other iron tests.

Hemoglobin (Hgb) electrophoresis, highperformance liquid chromatography, or isoelectric focusing is the best means for determining the specific Hgbs present in a patient sample. Solubility testing is a good screen to look for abnormal Hgbs,but does not determine specific Hgb presence or approximate quantities. Bone marrow analysis is an invasive technique and does not provide a definitive listing for the Hgbs present. Peripheral smear review may show the presence of sickle cells; however, it will not determine if Hgb S is present in the case of someone heterozygous for Hgb S.

Osmotic fragility is decreased when numerous sickle cell and target cells are present and is increased in the presence of Spherocytes whereas this test is decreased when sickle cells, target cells & other poikilocytes are present.

a-Naphthyl acetate esterase can be used to exhibit positive esterase activity in monocytes, whereas neutrophils and lymphocytes usually stain negative. Naphthyl AS-D chloroacetate esterase shows positive activity in granulocytic cells with negative or weak reactions in monocytes. Periodic acid–Schiff stains glycogen and mucoproteins, and staining patterns may be used to help in identification of various cell types. Myeloperoxidase activity is strong in neutrophils from the promyelocyte stage through maturity; however, activity in monocytes is negative or weak.

Excessive anticoagulant causes shrinkage of cells thus, the Hct will be affected RBC & WBC remain the same as does the Hb content.

EDTA and sodium citrate can be used without any effect of the ESR. Anisocytosis and Poikilocytsis may slow rouleaux formation, thus causing a low ESR. Plasma proteins, especially fibrinogen and immunoglobulins enhance rouleaux increasing the ESR.

Hematopoietic stem cells can make copies of themselves to maintain the stem cell pool and possess the ability to generate the cell of all lineage. Stem cell and progenitor cells cannot be morphologically distinguished but can be identified phenotypically by marker, such as the stem cell marker CD34. CD34 expression is lost as antigens for a specific cell lineage are expressed. CD13 is a marker expressed by myeloid precursors.

The biconcave, discoid geometry of the RBC is dependent on vertical and horizontal interactions between the transmembrane and cytoskeletal proteins. Two transmembrane protein complexes, the ankyrin comlex and protein 4.1 complex provide vertical structural integrity to the cell by anchoring the lipid bilayer to the underlying spectrin cytoskeleton. Spectrin is a cytoskeletal protein that is responsible for cell shape, deformability and stability.

Bone marrow core biopsies are the best indicator of bone marrow architecture and cellularity, because they provide a visual representation of the hematologic cells, fat, and vascular structure. Although a general idea may be obtained by examining the aspirate, it is better used for looking at the specific cell morphology. The buffy coat or concentrated smears concentrate any cells present, particularly in cases of hypocellular samples.

The bone marrow is the site of intramedullary hematopoiesis. The liver and spleen are sites of hematopoietic activity in the embryo, and hematopoietic activity may be renewed in cases of bone marrow compromise, such as primary myelofibrosis. The thymus is a site for lymphoid development.

Siderocytes are red cells containing iron granules and are visible with Prussian blue stain.

MCV is the average ‘volume’ of the red cells. This is obtained by dividing the Hct or PCV by the red blood cells (RBC) count in millions per ml of blood and multiplying by 10.

One of the reasons for increased intestinal absorption of iron is an accelerated rate of erythropoiesis. Although the mucosal cells does not act as a barrier in normal circumstances, this function is not absolute and controls break down in the presence of large amounts of iron, causing an excess to be absorbed. An acid pH is required for iron absorption, and sites of maximal absorption are the duodenum and upper jenunum.

During intravascular hemolysis haptolgobin binds free hemoglobin released from erythrocytes with high affinity and the complex is transported to the liver, where it is metabolized to bilirubin. Depletion of the haptoglobin protein may occur when use exceeds production and then hemopexin binds hemoglobin for removal. When both haptoglobin and hemopexin are depleted, plasma hemoglobin levels will increase. The Plasma Hb, bilirubin, lactate dehydrogenase rise following hemolysis.

The pH of the buffer is critical in Romanowsky stains when the pH is too low (<6.4), the red cells take up more acidic dye, becoming too pink. Leukocytes also show poor nuclear detail when the pH is decreased.

Need for oxygen delivery to developing tissue results in the production of erythrocytes before other blood cells. Erythropoiesis commences in the yolk sac as early as the fourteenth day of embryonic development. These primitive red cells produce embryonic hemoglobins that temoraily serve oxygen needs of the fetus. Myelopoietic and lymphopoietic activities begin when the liver and spleen becomes sites of production at 6-9 weeks of gestation; however erythropoiesis still predominates. At this time, the red cells produce hemoglobin F which is the chief oxygen carier during fetal life.

Glucose-6-dehydrogenase (G6PD) deficiency shows lack of enzyme activity that is needed for the reduction of glutathione, whichin turn works to deal with protecting hemoglobin from oxidant damage. Defective globin chains can be seen in hemolytic hemoglobinopathies or thalassemia. Antibodies to red blood cells are present in immune-mediated hemolytic anemias, and abnormal protein structure is seen in disorders such as hereditary elliptocytosis or hereditary spherocytosis.

Chemical signals such as cytokines and interleukins are uniquely responsible for promoting a specific lineage of cell. They control replication clonal or lineage selection and are responsible for maturation rate and growth inhibition of stem cells.

Haptoglobin forms a 1:1 complex with alpha-beta dimers of hemoglobin. The large size of this complex prevents filtration of the hemoglobin through the kindeys, where it can cause renal damage. Haptoglobin can be depleted in the plasma during major hemolytic events, such as malarial attacks, transfusion reactions and other causes of severe intravascular red cell destruction.

Variation in normal size is denoted by Anisocytosis. Hypochromia is a term that indicates increased central pallor erythrocytes. & poikilocytosis denotes variation in red cells shape.