Hematology Complete Review

What is anisocytosis?

Variation in RBC SIZE. A high RDW supports increased size variation.

What is poikilocytosis?

Variation in RBC SHAPE.

What does a normal RBC look like on Wright stain?

Reddish-pink, approximately 7-8 micrometers, with central pallor approximately one-third of its diameter.

What does normocytic mean?

Normal RBC size; MCV 80-100 fL.

What does microcytic mean?

Small RBCs; MCV below 80 fL.

What does macrocytic mean?

Large RBCs; MCV above 100 fL.

Why can defective hemoglobin synthesis produce microcytes?

Additional cell divisions produce smaller cells when hemoglobin production is inadequate.

What conditions can produce microcytes in the lecture?

Iron deficiency, thalassemia, sideroblastic anemia, anemia of chronic disease, and lead poisoning.

What three mechanisms of macrocytosis does the lecture list?

Impaired DNA synthesis with fewer divisions; early release of immature RBCs; increased membrane cholesterol and lecithin.

What does hypochromic mean?

Reduced hemoglobin concentration; enlarged central pallor. Common teaching cutoff: MCHC below 32 g/dL.

What does normochromic mean?

Normal hemoglobin concentration and usual central pallor; common MCHC interval 32-36 g/dL.

Why should high MCHC not automatically be called hyperchromia?

True MCHC elevations can occur, such as in spherocytosis, but an unexpectedly high result can also reflect interference. Check the smear and specimen.

What is polychromasia?

Immature RBCs appear gray-blue on Wright stain because of residual RNA.

How do Wright stain and supravital stain show young RBCs differently?

Wright stain shows polychromasia; supravital staining demonstrates the reticulocyte RNA network.

Where are reticulocytes produced?

Bone marrow, from erythroid precursors after nuclear extrusion.

What can increased reticulocytes indicate?

A marrow response to RBC loss/destruction or recovery from anemia. Interpret relative to the degree of anemia.

What is a dimorphic RBC population?

Two distinct RBC populations, such as small cells mixed with normal or large cells; RDW may be high.

What does MCV measure?

Mean corpuscular volume: average RBC size, reported in fL.

What does MCH measure?

Mean corpuscular hemoglobin: average hemoglobin amount per RBC, reported in pg.

What does MCHC measure?

Mean corpuscular hemoglobin concentration: hemoglobin concentration within the RBC population, reported in g/dL.

What does RDW measure?

Red cell distribution width: variation in RBC size. RDW-CV is a percentage; RDW-SD is reported in fL.

What does MPV measure?

Mean platelet volume: average platelet size, reported in fL.

What does PDW measure?

Platelet distribution width: variation in platelet size. Units and calculation depend on the analyzer.

How do MCV and RDW differ?

MCV is the AVERAGE RBC size; RDW is the VARIATION in RBC size.

How do MPV and PDW differ?

MPV is the AVERAGE platelet size; PDW is the VARIATION in platelet size.

What does high RDW suggest on a smear?

Anisocytosis: RBCs vary in size. A normal MCV can hide mixed small and large cells.

What does high PDW indicate?

Greater variation in platelet size; it does not by itself diagnose a disease.

What does high MPV indicate?

Larger platelets on average. Increased turnover can produce larger young platelets, but MPV alone is not diagnostic.

What MCV interval should you memorize?

80-100 fL: below 80 is microcytic; above 100 is macrocytic.

What MCH interval is commonly taught?

Approximately 27-33 pg. Verify the exact interval used in class.

What MCHC interval is commonly taught?

32-36 g/dL. Low MCHC supports hypochromia.

What RDW-CV interval is commonly taught?

Approximately 11.5-14.5%; exact intervals vary by laboratory and analyzer. Confirm your class interval.

What MPV range is confirmed for this set?

Your earlier class notes recorded approximately 7-8 fL, but the source slide has not been verified. Do not treat it as a universal normal interval.

What PDW range should you memorize?

The professor's analyzer-specific interval. It has not been verified in the available class material, so no universal range is assigned here.

Are relative and absolute counts classifications for MCV, MCH, or PDW?

No. Relative and absolute counts describe cell populations, especially the WBC differential. Indices describe size, hemoglobin, or size variation.

What units must you use in the standard RBC index formulas?

Hgb in g/dL; Hct as a whole-number percentage (36, not 0.36); RBC count in millions/microliter (4.0, not 4,000,000).

What is the MCV formula?

MCV (fL) = Hct (%) x 10 / RBC count (millions/microliter).

What is the MCH formula?

MCH (pg) = Hgb (g/dL) x 10 / RBC count (millions/microliter).

What is the MCHC formula?

MCHC (g/dL) = Hgb (g/dL) x 100 / Hct (%).

What is the calculated hematocrit formula?

Hct (%) = RBC count (millions/microliter) x MCV (fL) / 10.

Calculate MCV: Hct 36%, RBC 4.0 million/microliter.

36 x 10 / 4.0 = 90 fL; normocytic.

Calculate MCH: Hgb 12 g/dL, RBC 4.0 million/microliter.

12 x 10 / 4.0 = 30 pg.

Calculate MCHC: Hgb 12 g/dL, Hct 36%.

12 x 100 / 36 = 33.3 g/dL; normochromic.

Calculate MCV: Hct 27%, RBC 4.5 million/microliter.

27 x 10 / 4.5 = 60 fL; microcytic.

Calculate MCHC: Hgb 8 g/dL, Hct 30%.

8 x 100 / 30 = 26.7 g/dL; hypochromic.

What is the RBC-Hgb-Hct rule of three?

For typical normocytic, normochromic specimens: Hgb approximately RBC x 3, and Hct approximately Hgb x 3. It is an approximate consistency check.

When can the rule of three fail?

Abnormal RBC size/chromicity or analytical interference. It is not an exact rule for every specimen.

What is the relative differential formula?

Relative % = cells of one WBC type / total WBCs counted x 100.

What is the absolute differential formula?

Absolute cells/microliter = total WBC count x relative percentage / 100.

What is the ANC formula when bands are listed separately?

ANC = total WBC x (% segmented neutrophils + % bands) / 100. Do not add bands again if already included in the reported neutrophil percentage.

Calculate absolute lymphocytes: WBC 10,000/microliter, lymphocytes 30%.

10,000 x 0.30 = 3,000 lymphocytes/microliter.

Calculate ANC: WBC 4,000/microliter, segs 40%, bands 5%.

4,000 x 0.45 = 1,800 neutrophils/microliter.

What is the general hemocytometer formula?

Cells/microliter = cells counted x dilution factor / (area counted in square mm x chamber depth in mm).

What is the usual hemocytometer chamber depth?

0.1 mm. Area x depth gives volume in cubic mm, which equals microliters.

What is the WBC multiplier for a 1:20 dilution and four large squares?

20 / (4 x 0.1) = 50. Multiply the number counted by 50.

Calculate WBC: 120 cells, four large squares, dilution 1:20.

120 x 50 = 6,000 WBC/microliter.

Why must you check dilution and counting area before using a multiplier?

A different dilution or area changes the volume correction and the final multiplier.

What is the reticulocyte percentage formula?

Retic % = reticulocytes counted / total RBCs counted x 100.

What is the absolute reticulocyte count formula?

Absolute retics = RBC count (cells/microliter) x retic % / 100. Convert millions/microliter to cells/microliter first.

Calculate absolute retics: RBC 4 million/microliter, retics 2%.

4,000,000 x 0.02 = 80,000 reticulocytes/microliter.

What is the corrected reticulocyte percentage formula?

Corrected retic % = retic % x patient Hct / reference Hct. Use the reference Hct supplied by your course or question.

What is the RPI formula?

Reticulocyte production index = corrected retic % / maturation correction factor. Use the factor supplied in the question.

What is the dilution factor formula?

Dilution factor = total volume / specimen volume.

What is the original concentration after dilution?

Original concentration = measured diluted result x dilution factor.

What is the dilution factor for 0.1 mL specimen plus 0.9 mL diluent?

1.0 / 0.1 = 10; multiply the measured diluted result by 10.

What is the mean formula?

Mean = sum of all results / number of results.

What is the sample standard deviation formula?

SD = square root of [sum of (each result - mean)^2 / (n - 1)].

What is the coefficient of variation formula?

CV (%) = SD / mean x 100.

Calculate CV: mean 100, SD 2.

2 / 100 x 100 = 2%.

What is the RDW-CV formula?

RDW-CV (%) = SD of RBC volume / MCV x 100.

Do MPV and PDW share the RBC index formulas?

No. MPV and PDW are derived from platelet volume data by the analyzer. PDW methodology varies.

What identifies a target cell?

Bull's-eye: central hemoglobin, surrounding pallor, and an outer hemoglobin rim. Also called a codocyte.

Why do target cells form?

Excess membrane relative to cell contents: increased membrane lipids and/or decreased hemoglobin.

What conditions does the lecture associate with target cells?

Hb C disease/trait, liver disease, iron deficiency, hemoglobin abnormalities, and post-splenectomy.

How does the lecture describe target-cell osmotic fragility?

Decreased osmotic fragility; excess membrane helps the cell tolerate swelling.

What identifies a spherocyte?

Small, round, dense RBC with no central pallor.

What causes the spherocyte shape?

Membrane loss lowers the surface-area-to-volume ratio; the cell becomes spherical.

What conditions are associated with spherocytes?

Hereditary spherocytosis, immune hemolytic anemia, and post-transfusion states.

What membrane protein does the lecture emphasize in hereditary spherocytosis?

Spectrin: decreased quantity and/or function.

How do ovalocytes and elliptocytes differ in the lecture?

Ovalocytes are egg-shaped; elliptocytes are elongated or pencil-shaped.

What conditions are associated with ovalocytes?

Myelodysplastic syndrome, thalassemic syndromes, and megaloblastic processes.

What conditions are associated with elliptocytes?

Hereditary elliptocytosis, iron deficiency anemia, and idiopathic myelofibrosis.

What causes hereditary elliptocytosis in the lecture?

A membrane protein defect involving spectrin and related proteins; hemolysis may occur.

What identifies a stomatocyte?

Slit-like or mouth-shaped central pallor.

What conditions does the lecture associate with stomatocytes?

Hereditary stomatocytosis, hereditary spherocytosis, acute alcoholism, Rh-null phenotype, and artifact.

What identifies an acanthocyte?

Irregularly spaced projections of unequal size; the lecture describes 3-12 spicules.

What membrane changes does the lecture associate with acanthocytes?

Increased cholesterol and decreased lecithin; altered membrane lipids.

What conditions does the lecture associate with acanthocytes?

Severe liver disease, Zieve's syndrome, pyruvate kinase deficiency, abetalipoproteinemia, vitamin E deficiency, and post-splenectomy.

What identifies an echinocyte or burr cell?

Numerous short, relatively uniform, evenly spaced projections.

How can you distinguish acanthocytes from echinocytes?

Acanthocytes have irregular, uneven projections; echinocytes have more uniform, evenly spaced projections.

What does the lecture associate with echinocytes/burr cells?

Artifact; true burr cells can occur with uremia/azotemia, dehydration, hypothyroidism, heart disease, stomach cancer, peptic ulcer, or after heparin.

What identifies a schistocyte?

A broken RBC fragment, often angular or helmet-shaped.

What causes schistocytes?

Mechanical injury and membrane loss as RBCs pass through abnormal circulation or damaging structures.

What conditions are associated with schistocytes?

Microangiopathic hemolytic anemia, DIC, HUS, TTP, heart valve surgery, and burns.

What is a helmet cell also called?

Keratocyte; a form of RBC fragmentation with a helmet-like outline.

What is a bite cell also called?

Degmacyte; an RBC with a portion appearing bitten out. Do not treat every bite cell as a helmet cell.

What identifies a teardrop cell?

Pear-shaped RBC with a tail.

What conditions does the lecture associate with teardrop cells?

Myelofibrosis, thalassemia, iron deficiency, inclusion-body formation, drug-induced Heinz bodies, and megaloblastic processes.

What is a drepanocyte?

A sickle cell: elongated, rigid RBC with pointed ends.

What triggers sickling in the lecture?

Low oxygen promotes hemoglobin structures that bundle and deform the RBC.