Heme 1.8 Hematology Problem-Solving

Question 1

1. A 19-year-old man came to the emergency department with severe joint pain, fatigue, cough, and fever. Review the following laboratory results:
   WBCs 21.0 × 10^9/L
   RBCs 3.23 × 10^12/L
   Hgb 9.6 g/dL
   PLT 252 × 10^9/L
   Differential:
   17 band neutrophils
   75 segmented neutrophils
   5 lymphocytes
   2 monocytes
   1 eosinophil
   26 NRBCs
   What is the corrected WBC count?

A. 8.1 × 10^9/L
B. 16.7 × 10^9/L
C. 21.0 × 10^9/L
D. 80.8 × 10^9/L

Answer 1

B. 16.7 × 10^9/L

The formula for correcting the WBC count for the presence of NRBCs is:
Total WBC × 100 or (21.0 × 100) ÷ 126 = 16.7 × 10^9/L
where total WBC = WBCs × 10^9/L, 100 is the number of WBCs counted in the differential, and 126 is the sum of NRBCs plus WBCs counted in the differential.

Question 2

2. A manual WBC count is performed. Eighty WBCs are counted in the four large corner squares of a Neubauer hemacytometer. The dilution is 1:100. What is the total WBC count?

A. 4.0 × 10^9/L
B. 8.0 × 10^9/L
C. 20.0 × 10^9/L
D. 200.0 × 10^9/L

Answer 2

C. 20.0 × 10^9/L

The formula for calculating manual cell counts using a hemacytometer is:
# cells counted × 10 (depth factor) × dilution factor ÷ area counted in mm^2
or
(80 × 10 × 100) ÷ 4 = 20,000/µL
or
20.0 × 10^9/L

Question 3

3. A manual RBC count is performed on pleural fluid. The RBC count in the large center square of the Neubauer hemacytometer is 125, and the dilution is 1:200. What is the total RBC count?

A. 27.8 × 10^9/L
B. 62.5 × 10^9/L
C. 125.0 × 10^9/L
D. 250.0 × 10^9/L

Answer 3

D. 250.0 × 10^9/L

Regardless of the cell or fluid type, the formula for calculating manual cell counts using a hemacytometer is:
# cells counted × 10 (depth factor) × dilution factor ÷ area counted in mm^2
or
(125 × 10 × 200) ÷ 1 = 250,000/µL
or
250.0 × 10^9/L

Question 4

4. Review the scatterplot of WBCs shown (pg 64 of PDF). Which section of the scatterplot denotes the number of monocytes?

A. A
B. B
C. C
D. D

Answer 4

A. A

Question 5

5. Review the following automated CBC values.
   WBC = 17.5 × 10^9/L (flagged)
   RBC = 2.89 × 10^12/L
   Hgb = 8.1 g/dL
   Hct = 25.2%
   MCV = 86.8 fL
   MCH = 28.0 pg
   MCHC = 32.3%
   PLT = 217 × 10^9/L
   Many sickle cells were observed on review of the peripheral blood smear. On the basis of this finding and the results provided, what automated parameter of this patient is most likely inaccurate, and what follow-up test should be done to accurately assess this parameter?

A. MCV/perform reticulocyte count
B. Hct/perform manual Hct
C. WBC/perform manual WBC count
D. Hgb/perform serum–saline replacement

Answer 5

C. WBC/perform manual WBC count

Question 6

6. Review the following CBC results for a 2-day-old infant:
   WBC = 15.2 × 10^9/L
   RBC = 5.30 × 10^12/L
   Hgb = 18.5 g/dL
   Hct = 57.9%
   MCV = 105 fL
   MCH = 34.0 pg
   MCHC = 33.5%
   PLT = 213 × 10^9/L
   These results indicate:

A. Macrocytic anemia
B. Microcytic anemia
C. Liver disease
D. Normal values for a 2-day-old infant

Answer 6

D. Normal values for a 2-day-old infant

Question 7

7. Review the following scatterplot, histograms, and automated values for a 21-year-old college student. (pg 66 on PDF)
   WBC differential:
   5 band neutrophils
   27 segmented neutrophils
   60 atypical lymphocytes
   6 monocytes
   1 eosinophil
   1 basophil
   What is the presumptive diagnosis?

A. Infectious mononucleosis
B. Monocytosis
C. CLL
D. β-Thalassemia

Answer 7

A. Infectious mononucleosis

Question 8

Review the following scatterplot, histograms, and automated values for a 61-year-old woman. (pg 67 on PDF)
WBC differential:
14 band neutrophils
50 segmented neutrophils
7 lymphocytes
4 monocytes;
10 metamyelocytes
8 myelocytes
1 promyelocyte
3 eosinophils
3 basophils
2 NRBCs/100 WBCs

What is the presumptive diagnosis?
A. Leukemoid reaction
B. CML
C. AML
D. Megaloblastic leukemia

Answer 8

B. CML

Question 9

9. Review the automated results from the previous question. (pg 68 on PDF) Which parameters can be released without further follow-up verification procedures?

A. WBC and relative percentages of WBC populations
B. RBCs and PLTs
C. Hgb and Hct
D. None of the automated counts can be released without follow-up verification

Answer 9

D. None of the automated counts can be released without follow-up verification

Question 10

10. Refer to the following scatterplot, histograms, and automated values for a 45-year-old
    man. (pg 69 on PDF) What follow-up verification procedure is indicated before these results can be released?

A. Redraw blood sample using a sodium citrate tube; multiply PLTs × 1.11
B. Dilute WBCs 1:10; multiply × 10
C. Perform plasma blank Hgb to correct for lipemia
D. Warm specimen at 37°C for 15 minutes; rerun specimen

Answer 10

A. Redraw blood sample using a sodium citrate tube; multiply PLTs × 1.11

The PLT clumping phenomenon is often induced in vitro by the anticoagulant EDTA. Redrawing a sample from the patient by using a sodium citrate tube usually corrects this phenomenon and allows for accurate PLT enumeration. The PLT count must be multiplied by 1.11 to adjust for the amount of sodium citrate. PLT clumps cause a spurious decrease in the PLT count by automated methods. The WBC value has an “R” (review) flag because the PLT clumps have been falsely counted as WBCs; therefore, a manual WBC count is indicated.

Question 11

11. Refer to the following scatterplot, histograms, and automated values for a 52-year-old woman. (pg 70 on PDF) What follow-up verification procedure is indicated before these results can be released?

A. Redraw specimen using a sodium citrate tube; multiply PLTs × 1.11
B. Dilute WBCs 1:10; multiply × 10
C. Perform plasma blank Hgb to correct for lipemia
D. Warm the specimen at 37°C for 15 minutes; rerun the specimen

Answer 11

D. Warm the specimen at 37°C for 15 minutes; rerun the specimen

The presence of high-titer cold agglutinin in a patient with cold AIHA will interfere with automated cell counting. The most remarkable findings are falsely elevated MCV, MCH, and MCHC, as well as falsely decreased RBC count. The patient’s RBCs will quickly agglutinate in vitro when exposed to ambient temperatures below body temperature. To correct for this phenomenon, the EDTA tube should be incubated at 37°C for 15 to 30 minutes, and then the specimen should be rerun.

Question 12

12. Refer to the following scatterplot, histograms, and automated values for a 33-year-old woman (pg 71 on PDF). What follow-up verification procedure is indicated before these results can be released?

A. Perform a manual Hct and redraw the sample using a sodium citrate tube; multiply PLTs × 1.11
B. Dilute WBCs 1:10; multiply × 10
C. Perform plasma blank Hgb to correct for lipemia
D. Warm the specimen at 37°C for 15 minutes; rerun the specimen

Answer 12

C. Perform plasma blank Hgb to correct for lipemia

The rule of thumb regarding the Hgb/Hct correlation dictates that Hgb × 3 ≈ Hct (±3). This rule has been violated in this patient; therefore, a follow-up verification procedure is indicated. Additionally, MCHC is markedly elevated in these results, and an explanation for falsely increased Hgb should be sought. Lipemia can be visualized by centrifuging the EDTA tube and observing for a milky white plasma. To correct for the presence of lipemia, a plasma Hgb value (baseline Hgb) should be ascertained by using the patient’s plasma and subsequently subtracted from the original falsely elevated Hgb value. The following formula can be used to correct for lipemia:
Whole blood Hgb – [(Plasma Hgb) (1 – Hct/100)] = Corrected Hgb

Question 13

13. Refer to the following scatterplot, histograms, and automated values for a 48-year-old man (pg 72 on PDF). What follow-up verification procedure is indicated before the five-part WBC differential results can be released?

A. Dilute WBCs 1:10; multiply × 10
B. Redraw the sample using a sodium citrate tube; multiply WBCs × 1.11
C. Prepare buffy coat peripheral blood smears, and perform a manual differential
D. Warm specimen at 37°C for 15 minutes; rerun specimen

Answer 13

C. Prepare buffy coat peripheral blood smears, and perform a manual differential

Question 14

14. Review the following CBC results for a 70-year-old man:
    WBC = 58.2 × 10^9/L
    RBC = 2.68 × 10^12/L
    MCV = 98 fL
    MCH = 31.7 pg
    MCHC = 32.6%
    Hgb = 8.5 g/dL
    Hct = 26.5 mL/dL%
    PLT = 132 × 10^9/L
    Differential:
    96 lymphocytes
    2 band neutrophils
    2 segmented neutrophils
    25 smudge cells/100 WBCs
    What is the most likely diagnosis on the basis of these values?

A. ALL
B. CLL
C. Infectious mononucleosis
D. Myelodysplastic syndrome

Answer 14

B. CLL

Question 15

15. Refer to the following scatterplot, histograms, and automated values for a 28-year-old woman who had undergone preoperative laboratory testing. (pg 74 on PDF) A manual WBC differential was requested by her physician. The WBC differential was not significantly different from the automated five-part differential; however, the medical laboratory scientist noted 3+ elliptocytes/ovalocytes while reviewing the RBC morphology. What is the most likely diagnosis for this patient?

A. DIC
B. HE (ovalocytosis)
C. Cirrhosis
D. Hgb C disease

Answer 15

B. HE (ovalocytosis)

The finding of ovalocytes as the predominant RBC morphology in peripheral blood is consistent with the diagnosis of HE, or ovalocytosis. This disorder is relatively common and can range in severity from an asymptomatic carrier state to homozygous HE with severe hemolysis. The most common clinical subtype is associated with no or minimal hemolysis. Therefore, HE is usually associated with a normal RBC histogram and cell indices and will go unnoticed without microscopic evaluation of the peripheral blood smear.

Question 16

16. A 25-year-old woman presented with symptoms of jaundice, acute cholecystitis, and an enlarged spleen. On investigation, numerous gallstones were discovered. Review the following CBC results:
    WBC = 11.1 × 10^9/L
    RBC = 3.33 × 10^12/L
    MCV = 100 fL
    MCH = 34.5 pg
    MCHC = 37.5%
    Hgb = 11.5 g/dL
    Hct = 31.6 mL/dL
    PLT = 448 × 10^9/L
    WBC differential:
    13 band neutrophils
    65 segmented neutrophils
    15 lymphocytes
    6 monocytes
    1 eosinophil
    RBC morphology: 3+ spherocytes, 1+ polychromasia
    What follow-up laboratory test would provide valuable information for this patient?

A. Osmotic fragility test
B. Hgb electrophoresis
C. G6PD assay
D. Methemoglobin reduction test

Answer 16

A. Osmotic fragility test

The osmotic fragility test is indicated as a confirmatory test for the presence of numerous spherocytes, and individuals with HS have an increased osmotic fragility. MCHC is elevated in greater than 50% of patients with spherocytosis, and this parameter can be used as a clue to the presence of HS. Spherocytes have a decreased surface:volume ratio, probably resulting from mild cellular dehydration.

Question 17

17. Refer to the following scatterplot, histograms, and automated values for a 53-year-old man who had undergone preoperative laboratory testing. (pg 76 on PDF) What is the most likely diagnosis for this patient?

A. IDA
B. PV
C. Sideroblastic anemia
D. β-thalassemia minor

Answer 17

D. β-thalassemia minor

β-thalassemia minor can be easily detected by noting an abnormally elevated RBC count and Hct that does not correlate with the elevated RBC count, in conjunction with a decreased MCV. Although thalassemia and IDA are both microcytic, hypochromic processes, thalassemia can be differentiated from IDA because in IDA the RBC count, Hgb, and Hct values are usually decreased along with MCV. Although the RBC count is increased in PV, Hct must also be greater than 50% for a diagnosis of PV to be considered.

Question 18

18. Review the following CBC results:
    WBC = 11.0 × 10^9/L
    RBC = 3.52 × 10^12/L
    MCV = 85.0 fL
    MCH = 28.4 pg
    MCHC = 33.4%
    Hgb = 10.0 g/dL
    Hct = 29.9 mL/dL
    PLT = 155 × 10^9/L
    12 NRBCs/100 WBCs
    RBC morphology: Moderate polychromasia, 3+ target cells, few schistocytes
    Which of the following additional laboratory tests would yield informative diagnostic information for this patient?

A. Osmotic fragility test
B. Hgb electrophoresis
C. Sugar water test
D. Bone marrow examination

Answer 18

B. Hgb electrophoresis

The findings of moderate anemia, numerous target cells seen on the peripheral blood smear, and the presence of NRBCs are often associated with hemoglobinopathies. Hgb electrophoresis at alkaline pH is a commonly performed test to correctly diagnose the type of hemoglobinopathy.