Deck 10: Hematology

Question 1

What would a hematocrit of 24% indicate?

A) Red blood cells occupy 24 mL of every 100 mL of whole blood.
B) The platelets in a blood sample are 24% larger in volume than a normal platelet.
C) There are 24 red blood cells for every 100 white blood cells in a blood sample.
D) White blood cells make up 24 of every 100 cells present in whole blood.

Answer 1

Red blood cells occupy 24 mL of every 100 mL of whole blood.

Question 2

What is necessary when performing an osmotic fragility test?

A) A series of hypertonic solutions
B) A series of hypotonic solutions
C) A solution 98% solution of NaCl (w/v) and methylene blue stain
D) A solution of NaCl and a solution of FeCl₂ of equal concentration

Answer 2

A series of hypotonic solutions

Question 3

A low hematocrit value generally suggests

A) anemia.
B) hemophilia.
C) leukemia.
D) neutropenia.

Answer 3

anemia.

Question 4

A set of results that fails the Rule of Three may indicate that

A) the patient has a pathological condition.
B) the ratio of white blood cells to red blood cells is abnormal.
C) the red blood cells in the sample have all lysed.
D) the volume of blood obtained from the patient is insufficient for analysis.

Question 5

A clinical laboratory technician is asked to enumerate the red blood cells in a sample using the standard procedure.What is the single factor by which the technician can multiply the absolute number of cells counted on the hemacytometer to obtain an accurate final count?

A) 50
B) 200
C) 1,000
D) 10,000

Question 6

What is the hematocrit?

A) The concentration of platelets found in a blood sample
B) The mass percentage of blood made up of red and white blood cells
C) The ratio of the number of white blood cells to the number of platelets
D) The volume of whole blood occupied by packed red blood cells

Question 7

Which of the following is an important rule to follow when enumerating leukocytes?

A) The difference between any two counts should be less than 10, and the difference between the highest and lowest count should be less than 15.
B) The mean of the four counts on one side of the hemacytometer should be less than 10 units different from the mean of the four counts on the other side of the hemacytometer.
C) The total count from one side of the hemacytometer should differ from the total count on the other side of the hemacytometer by at least 20.
D) The values obtained from one side of the hemacytometer should be identical to those obtained from the other side of the hemacytometer.

Question 8

In order to correct a white blood cell (WBC)count for the presence of nucleated red blood cells (nRBCs),what information must be collected?

A) The average cell volume of nRBCs and WBCs
B) The number of nRBCs per 100 WBCs
C) The number of nRBCs per 1000 RBCs
D) The volume of nRBC in 100 mL whole blood

Question 9

A patient is suspected of having severe anemia.His hematocrit is 18%,reticulocyte count is 12%,and red blood cell count is 2.2 × 10⁶ cells/μL.A normal hematocrit is taken as 45%.Which of the following expressions should be used to calculate the patient's reticulocyte index?

A) (2.2 × 10⁶) ×
B) (2.2 × 10⁶) ×
C) 12 ×
D) 18 × 18 - 2.2 × 10⁶

Question 10

Reticulocytes are immature red blood cells that contain residual ribosomal RNA.What does counting reticulocytes tell us about a patient?

A) The blood type of the patient
B) The effectiveness of erythrocyte production
C) The severity of a patient's anisocytosis
D) The volume of red blood cells in whole blood

Question 11

What is the dilution factor for enumerating erythrocytes?

A) 1:2
B) 1:20
C) 1:100
D) 1:200

Question 12

An anemic patient has a reticulocyte production index (RPI)of 1.What does this value suggest?

A) Erythropoiesis is inadequate and indicative of possible pathology.
B) Erythropoiesis is occurring at a rate equal to red blood cell degradation.
C) Erythropoiesis is proceeding at a normal rate.
D) Both B and C are correct.

Question 13

What does the mean cell volume (MCV)of a sample tell us?

A) The average volume of the red blood cells
B) The concentration of abnormal platelets
C) The percentage of healthy versus abnormal red blood cells
D) The volume of non-nucleated white blood cells

Question 14

Why is it important to standardize the results of a prothrombin time (PT)test?

A) To account for the wide variation in commercial preparations of thromboplastin and the differences in instrumentation
B) To introduce a proportionality constant that ensures the results will fit onto the standard curve
C) To eliminate interference by anticoagulant drugs
D) None of the above

Question 15

You are asked to test the osmotic fragility of a patient's red blood cells (RBCs).After calculating the percent lysis,you plot the results.The patient's lysis curve is significantly shifted to the left of the normal curve.What does this indicate?

A) The patient's RBCs have a high osmotic fragility, consistent with the presence of spherocytes.
B) The patient's RBCs have a high osmotic fragility, consistent with the presence of target cells.
C) The patient's RBCs have a low osmotic fragility, consistent with the presence of spherocytes.
D) The patient's RBCs have a low osmotic fragility, consistent with the presence of target cells.

Question 16

Which of the following features about a thromboplastin preparation is necessary for accurate results?

A) Serial dilutions must be made of the thromboplastin preparation and measured to create a standard curve.
B) The international sensitivity index (ISI) of the thromboplastin preparation should be close to 1.
C) The thromboplastin preparation must be made by and purchased from the International Standardization Committee.
D) The thromboplastin preparation must be tested and certified by the World Health Organization (WHO).

Question 17

When a Miller disk is used to enumerate reticulocytes,which of the following counts are needed?

A) The number of red blood cells in both squares, and the number of reticulocytes in both squares
B) The number of red blood cells in both squares, and the number of reticulocytes in the small square
C) The number of red blood cells in the small square, and the number of reticulocytes in both squares
D) The number of red blood cells in the small square, and the number of reticulocytes in the small square

Question 18

A clinical laboratory technician is asked to determine the concentration of red blood cells (RBCs)from a sample of turbid knee fluid using a hemacytometer.The technician dilutes the sample with normal saline and loads it onto the hemacytometer.A total of 400 red blood cells are counted over 5 squares.What additional information is required to calculate the concentration of RBCs?

A) The WBC count
B) The dilution factor
C) The number of platelets
D) The red-cell distribution width