MLBT1010 Clinical Hematology – Core Review

A comprehensive set of Q&A flashcards covering key concepts, cells, laboratory indices, pathological variations, and procedures from the lecture on clinical hematology.

What percentage of an adult’s body weight is blood?

About 7%–8% of body weight (≈6 L).

What proportion of circulating blood is made up of cells?

Approximately 45% (RBCs, WBCs, and platelets).

Where does hematopoiesis occur during fetal life?

Begins in embryonic tissues, progresses to the fetal liver, then relocates to red bone marrow.

Which surface marker identifies pluripotent hematopoietic stem cells?

CD34⁺.

Which progenitor lineage produces erythrocytes, platelets, and granulocytes?

The myeloid progenitor lineage.

Name the lymphoid-derived cell types.

T lymphocytes, B lymphocytes, and natural killer (NK) cells.

Primary function of erythrocytes?

Transport oxygen to body tissues via hemoglobin.

What key elements must hemoglobin contain to transport oxygen?

Iron-containing heme and globin chains.

During RBC maturation, what happens to cell size and the nucleus?

Cell diameter shrinks, nucleus condenses and is eventually extruded.

List the six stages of erythrocyte maturation in order.

Rubriblast, Prorubricyte, Rubricyte, Metarubricyte, Reticulocyte, Mature erythrocyte.

Which erythroid stage shows intensely blue cytoplasm and 1% presence in marrow?

Rubriblast.

At which maturation stage does the erythrocyte first lose its nucleus?

Reticulocyte stage (after Metarubricyte extrusion).

Normal reference reticulocyte percentage in adult blood?

0.5%–1.5% of circulating RBCs.

What cellular changes characterize aging erythrocytes?

Membrane rigidity increases, Hb concentration rises, glycolytic enzymes decline.

Which system removes senescent RBCs from circulation?

Mononuclear phagocytic (reticuloendothelial) system.

How many heme groups are in one hemoglobin molecule?

Four heme groups.

What is oxyhemoglobin?

Hemoglobin fully saturated with four oxygen molecules.

Name the normal adult hemoglobins.

Hb-A1 and Hb-A2.

Which hemoglobin predominates in fetuses?

Hb F.

List four clinically important hemoglobinopathies.

HbS, HbC, HbD, HbE.

Define carboxyhemoglobin.

Hemoglobin bound to carbon monoxide instead of oxygen.

What adult Hb derivative is measured in diabetes monitoring?

HbA1C.

Key morphological criteria to identify leukocytes?

Nuclear chromatin, nuclear shape, nucleoli, cytoplasmic inclusions, and N:C ratio.

Order the maturation stages of neutrophils from youngest to mature.

Myeloblast, Promyelocyte, Myelocyte, Metamyelocyte, Band, Segmented neutrophil.

Function of neutrophil granules?

Contain digestive enzymes that destroy bacteria.

What drives neutrophils toward infection sites?

Chemotaxis.

Typical lifespan of eosinophils in peripheral blood?

Less than 8 hours.

Which granulocyte is prominent in allergic reactions and tissue-parasitic infections?

Eosinophils.

Main chemical mediators stored in basophil granules?

Histamine, heparin/heparin-like substances, and peroxidase.

Percentage range of neutrophils in normal adult leukocyte differential?

35%–71% (≈59% average).

What term describes increased absolute neutrophil count?

Neutrophilia.

Which leukocyte stage shows a horseshoe-shaped nucleus and abundant vacuoles?

Mature monocyte.

Primary functional role of lymphocytes?

Direct and regulate the immune response.

Origin organ of T-lymphocyte maturation?

Thymus.

End-stage differentiated B cell that secretes antibodies?

Plasma cell.

Cellular source of platelets in bone marrow?

Megakaryocytes.

Normal platelet size range?

1.5–4 µm in diameter.

Which CBC component reflects packed RBC volume?

Hematocrit (Hct).

Formula for Mean Corpuscular Volume (MCV)?

(Hct × 10) ÷ RBC count (in 10¹²/L).

Reference range for MCV?

80–96 fL.

Formula for Mean Corpuscular Hemoglobin (MCH)?

(Hb × 10) ÷ RBC count (in 10¹²/L).

Reference range for MCH?

27–33 pg.

Formula for Mean Corpuscular Hemoglobin Concentration (MCHC)?

(MCH ÷ MCV) × 100.

Reference range for MCHC?

33–36 g/dL.

What does an elevated Red Cell Distribution Width (RDW) indicate?

Greater anisocytosis (size variability) among RBCs.

Mode of action of EDTA as an anticoagulant?

Chelates ionized calcium, preventing coagulation.

Heparin inhibits clotting by inactivating which factor?

Thrombin (acts as an antithrombin).

Define isotonic solution in relation to cells.

Diluent concentration equals intracellular concentration; no net osmotic movement.

What two sample conditions make blood unsuitable for hematology testing?

Clotted samples and hemolyzed samples.

Instrumental method considered gold standard for lab hemoglobin measurement?

Hemiglobincyanide (cyanmethemoglobin) method.

Which RBC index must always be checked against smear morphology?

All three indices (MCV, MCH, MCHC) should be confirmed by blood-film appearance.

Clinical use of a high reticulocyte count?

Indicates bone marrow response to increased RBC demand (e.g., after anemia therapy).

Most important variable influencing ESR?

Size (rouleaux formation) of erythrocyte aggregates.

Minimum WBCs counted for a standard differential?

100 WBCs (50 if leukopenic).

Define Poikilocytosis.

Variation in RBC shape.

Appearance of a target cell (codocyte)?

Peripheral Hb ring, central pallor, then central Hb area—resembles a target.

Name the RBC inclusion that represents precipitated ribosomal RNA.

Basophilic stippling.

Which RBC inclusion is a small, round nuclear remnant seen in asplenic patients?

Howell-Jolly body.

Fragmented RBCs on smear are called what?

Schistocytes.

What does rouleaux formation resemble microscopically?

Stacks of coins alignment of RBCs.

Laboratory definition of anemia?

Hemoglobin concentration below reference range for age, sex, and altitude.

Morphologic classification of macrocytic anemia often indicates deficiency of which vitamins?

Vitamin B₁₂ and/or folic acid.

Most common broad category of anemia worldwide?

Hypochromic-microcytic (often iron-deficiency).

RDW pattern typical of hemolytic anemia?

Greatly increased due to anisocytosis and poikilocytosis.

Term for WBC count above normal range?

Leukocytosis.

Define Dӧhle bodies.

Pale blue, oval cytoplasmic inclusions in neutrophils indicating toxic change.

What cytoplasmic rods are diagnostic for acute myeloid leukemia?

Auer rods.

Inherited anomaly with hyposegmented neutrophil nuclei?

Pelger-Huët anomaly.

Blue inclusion bodies plus giant platelets characterize which anomaly?

May-Hegglin anomaly.

Reactive (atypical) lymphocytes are most associated with what infections?

Viral infections (e.g., infectious mononucleosis).

Damaged leukocytes on a smear are called what?

Smudge (basket) cells.

Which leukemia typically shows very high basophil counts?

Chronic myelogenous leukemia (CML).

Median survival without treatment for acute leukemias?

Measured in months.

What is the average untreated survival for CLL?

About 10 years (up to 35 years possible).

Normal platelet estimate per oil-immersion field?

6–20 platelets, correlating with 150–450 × 10⁹/L.

Define Mean Platelet Volume (MPV).

Average volume of platelets; increases as platelet count decreases.

Purpose of CLSI procedural guidelines?

Standardize lab procedures, ensuring quality and accuracy.

Key QC parameters for any hematology procedure?

Calibration, quality control samples, reference values, and documented steps.

What is a hypertonic solution’s effect on RBCs?

Water moves out; RBCs shrink (crenate).

What is methemoglobin?

Hemoglobin in which iron is oxidized to Fe³⁺, impairing oxygen binding.

Which abnormal Hb derivative gives blood a chocolate-brown color?

Methemoglobin.

‘Blue-black’, coarse cytoplasmic granules in neutrophils describe what toxic change?

Toxic granulation.

Term for increased eosinophils due to allergic or drug reactions?

Eosinophilia.

Mechanism by which sodium citrate acts as an anticoagulant?

Binds calcium by precipitation, rendering it unavailable for clotting cascade.

Why must EDTA blood films be made within 2 hours?

Prevent morphological artifacts in cells (e.g., RBC crenation).

Interpretation when fewer than 6 platelets/field are seen on a smear?

Report platelet count as decreased.

Which RBC shape resembles a teardrop and is typical in myelofibrosis?

Dacryocyte (teardrop cell).

Name the oval RBCs common in hereditary elliptocytosis.

Elliptocytes/ovalocytes.

What small knob on neutrophil nucleus represents an inactivated X chromosome?

Barr body.

What parameter is calculated as (SD of MCV ÷ mean MCV) × 100?

Red Cell Distribution Width (RDW).

Explain ‘left shift’ in neutrophil series.

Increased proportion of immature neutrophil forms (bands, metamyelocytes) in blood.

Which RBC membrane defect produces round, dense cells lacking central pallor?

Spherocytosis (hereditary or acquired).

State two main roles of platelets in hemostasis.

Form mechanical plugs at vessel injury and release clotting factors.

What is the clinical significance of the Westergren ESR?

Non-specific indicator of inflammation.

Define leukopenia.

Total WBC count below normal reference range.

Name two major categories of hemolytic anemia.

Acquired hemolytic anemia and congenital hemolytic anemia.

Describe a helmet cell.

Triangular RBC fragment with one or two straight edges; subtype of schistocyte.

Which abnormal red cell distribution pattern looks like coin stacks?

Rouleaux formation.

What is the normal adult range for hemoglobin concentration at sea level (approximate)?

Men: 13.5–17.5 g/dL; Women: 12.0–16.0 g/dL (values vary by source).

High altitude has what effect on Hb concentration?

Increases normal reference hemoglobin values.