MediaLab

A manual WBC was performed. A total of 36 cells were counted in all 9 mm(2) of a neunbauer-ruled hemocytometer, A 1:10 dilution was used. What was the WBC Count?

The formula used for calculating manual cell counts using a hemocytometer is: Number of cells counted x dilution factor x depth factor (10) divided by the area, In this example (15/47)x10(9)=31.9%

A 1:20 dilution is made for a manual WBC count. The four corner squares on both sides of a hemocytometer are counted. A total of 100 cells are counted (eight total squares). What is the white blood cell count in terms of a liter? a. 2.5x10^9/L b. 25x10^9/L c. 2500/L d. 25,000/L

a. 2.5x10^9/L

At an alkaline pH, which of the following hemoglobins cannot be separated from hemoglobin S during hemoglobin electrophoresis? a. Hb D b. Hb C c. Hb A d. Hb F

a. Hb D Hemoglobin S, D and G will migrate to the same position using cellulose acetate at an alkaline pH (8.6) Hemoglobin C migrates with A2 and E using cellulose acetate at an alkaline pH Hemoglobin A migrates alone using cellulose acetate at an alkaline pH Hemoglobin F migrates alone using cellulose acetate at an alkaline pH

What is a typical finding for determining the endpoint for the initial or iron-depletion phase of treatment for hereditary hemochromatosis (HH)? a. the serum ferritin decreases to between 20 and 50 ng/mL b. The hepatic iron index returns to normal c. The transferrin saturation drops below 20% d. the serum iron falls to below 35 ug/dL

a. The serum ferritin decreases to between 20 and 50 ng/dmL Hereditary hemochromatosis is a disease that causes increased absorption of iron which leads to excess iron storage in the bone marrow, heart, and liver. The end of the initial phase of HH treatment is considered when the serum ferritin decreases to between 20 and 50 ng/mL. Ferritin levels will decrease rapidly as storage iron is depleted. Serum ferritin is an inexpensive, non-invasive lab test. The hepatic iron index is a calculation of the iron concentration in the liver and a sensitive indicator for determining the degree of excess iron deposition in the liver. However, this is an invasive and costly procedure which requires a liver biopsy Transferrin saturation and serum iron will eventually decrease after iron stores have been depleted, however, they will not be the first indicators of successful treatment of HH.

A defective clot retraction might be caused by which one of these? a. lack of or defect of platelet receptor glycoprotein Ib/IX/V b. lack of or defect of platelet receptor IIb/IIIa c. Insufficient storage of ADP in platelet granules d. absence or defect of von Willebrand's factor

b. lack of or defect of platelet receptor IIb/IIIa Clot retraction is the process of the compaction of a formed blood clot by activated platelets inside the clot Glycoprotein IIb/IIIa is integral in the process of plateelt aggregation as well as clot retraction. Glycoprotein Ib/IX/V binds to VWF and thrombin to facilitate platelet adhesion. ADP released from platelet storage granules provides energy to produce. Thromoxan A2 which stimulates platelet aggregation. An absence or defect in von Willebrand Factor will result in decreased plateelt adhesion to blood vessel walls and decreased sruvival of Factor VIII

Which of the following methods is NOT used to detect and differentiate white blood cells in most hematology analyzers? a. Disruption of electrical current b. conductivity measurement using high frequency electromagnetic probe c. forward angle light scatter d. lysis of white cells with subsequent conversion to hemiglobibncyanide followed by colorimetric determination

d. Lysis of white cells with subsequent conversion to hemiglobincyanide followed by colorimetric determination

A sample of cerebrospinal fluid is diluted 1:100; the standard 9 squares of a hemocytometer are counted on each side for a total of 18 large squares Side 1 - 186 nucleated cells counted Side 2 - 184 nucleated cells counted Total nucleated cells = 370 Using the standard hemocytometer formula, what is the nucleated cell count per microliter? a. 1.03x10^4 b. 2.06x10^4 c. 4.12x10^4 d. 8.24x10^4

formula: cell/uL = (number of cells counted x dilution)/(number of larger squares counted x 0.1)

When three tubes of cerebrospinal fluid are received in the laboratory they should be distributed to the various laboratory sections as follows: a. #1 Hematology, #2 Chemistry, #3 Microbiology b. #1 Chemistry, #2 Microbiology, #3 Hematology c. #1 Microbiology, #2 Hematology, #3 Chemistry d. #1 Chemistry, #2 Hematology, #3 Microbiology

b. #1 Chemistry, #2 Microbiology, #3 Hematology

When performing a manual white blood cell count, 236 cells were counted on side number one of the hemacytometer, 224 cells on side number two. A 1/20 dilution of 1% HCl was used and the area counted on each side was 4 sq mm. Twenty-five nucleated red blood cells in the differential were observed per 100 white blood cells. What is the CORRECT WBC/uL? a. 8,500 b. 9,200 c. 9,575 d. 12,425

b. 9,200 WBC calculation = ((# of Cells Counted x Dilution Factor x Depth Factor)/(# of Square Millimeters Counted)) = WBC per mm^3 Average of 236+224=230 dilution factor = 20 area counted = 4mm2 So.. 230 cells x 20 x 10 / 4 = 11,500 Corrected WBC count calculation = uncorrected WBC counted x 100 / # of NRBCs + 100 So.. 11,500 x 100 / 25 + 100 = 9,200

Which of the following phenotypes is most indicative of a natural killer cell? a. CD2+ CD3+ CD5+ CD7+ b. CD2+ CD3- CD11b+ CD16+ c. CD11b+ CD16+ CD33+ CD56- d. CD19+ CD20+ CD22+ CD57-

b. CD2+ CD3- CD11b+ CD16+ NK cells express CDC2, CD11b, and CDC16; NK cells do not express CD3, a T cell marker. Other NK cell markers include CD7, CD56, and CD57. CD2, CD3, CD5 and CD7 are all mature T cell markers. CD2 and CD7 are also NK cell markers; however, NK cells are CD3- and CD5-. Although NK cells express CD11b and CD16, CD33 is expressed by monocytes and other myeloid cells. NK cells are CD56+. CD19, CD20, and CD22 are all B cell markers. NK cells are CD57+

A manual WBC count was performed. A TOTAL of 72 cells were counted in 4 large mm squares of a Neubauer-ruled hemacytometer. A 1:20 dilution was used. What is the calculated WBC count? a. 0.4x10^3/uL b. 1.8x10^3/uL c. 3.6x10^3/uL d. 4.0x10^3/uL

c. 3.6x10^3/uL First, determine the number of WBC's from the hemacytometer as follows: WBC count = (dilution ratio x #of cells counted x 10)/ (# mm2 area counted) Then: WBC count = (20 x 72 x 10)/ 4 = 3600 WBC/uL (or 3.6 x 10^3 WBC/uL)

The blood is diluted 1:100 and charged on the hemocytometer counting chambers on both sides. If the average platelet count from a counting chamber in one mm2 (one large square) is 68, what is the calculated platelet count? a. 680,000/mm3 b. 6,800/mm3 c. 68,000/mm3 d. 34,000/mm3

c. 68,000/mm3 A simple way to calculate platelet counts on the hemocytometer is to multiply the average plateelt count between the two sides of the chamber by 1,000. In this case 68 x 1,000 = 68,000 platelets. The longer derivation is asa follows: The standard dilution of blood for platelet counts is 1:100; therefore the dilution factor is 100. The volume of diluted blood used is based on the area and depth of the counting area. The area counted is 1mm2 per side (since we are using the average platelet count, we only use the area of one side) and the depth factor is 10. ((Total number of cells counted x dilution factor x depth factor (mm))/area in mm2) = platelets per mm3 Note: 10^3/mm3 = 10^3/uL = 10^9/L

The gel electrophoresis pattern for hemoglobin S (HbS) shows which of the following migration patterns? a. HbS migrates alone in alkaline and with HbD in acid electrophoresis b. HbS migrates with HbD in alkaline and with HbA in acid electrophoresis c. HbS migrates with HbD in alkaline and alone in acid electrophoresis d. HbS migrates with HbA in alkaline and HbD in acid electrophoresis

c. HbS migrates with HbD in alkaline and alone in acid electrophoresis HbS migrates with HbD (and HbG) in alkaline and alone in acid electrophoresis. On cellulose acetate (pH 8.6 = alkaline) HbS appears between HbF and HbA2. On citrate agar (pH 6.2 = acidic), HbS appears between HbC and HbA

Given the following information, what is the corrected white count? Initial White count = 35,000/uL 92 nucleated red blood cells are noted per 100 WBC's counted on the manual differential a. 3,500/uL b. 10,300/uL c. 16,700/uL d. 18,229/uL

d. 18,229/uL The corrected WBC count is calculated by utilizing the following formula: (Uncorrected WBC count x 100)/(NRBCs per 100 WBC's + 100) (35,000 x 100)/(92 + 100) = 18,229/uL