MT 417 – Clinical Hematology II Manual/Special Tests Unit

1. MT 417 – Clinical Hematology IIManual/Special Tests Unit Leukocyte Alkaline Phosphatase Exercise LAP Questions KEY

2. 1. What is the main reason this stain is performed? Mainly done to differentiate CML and leukemoid reactions caused by a severe bacterial infection; both are characterized by a neutrophilic leukocytosis. The LAP is also used to help differentiate chronic myeloproliferative disorders (PV, MMM, ET, CML), differ polycythemias (primary versus secondary type) and monitor remission.

3. Fingerstick blood smears are best but fresh, heparinized blood is most often used. EDTA anticoagulated blood is not acceptable because enzyme activity may be inhibited. Thin slides are made and must be fixed within 8 hours of blood collection. Note: The LAP stain is NOT done on bone marrow smears. 2. What is an acceptable patient specimen? 3. What control is used? Blood drawn from a woman in her third trimester of pregnancy or within 2 days post-partum.

4. 4. List in correct order the following LAP procedure steps: 3 Incubate slides in staining substrate solution Fix smears within specified time limit Count patient slide Prepare patient & control smears Validate control slide Counterstain smears 2 6 1 5 4

5. Neutrophilic leukocytes are positive, staining from a pale pink to a deep red color (color depends on type of salt used). 5. Which cells stain positive? 5. What is being detected? Detects activity of the enzyme alkaline phosphatase, pH 8.6, in the cytoplasm of neutrophils (secondary granules/membrane associated). The amount of dye precipitated is proportional to the amount of enzyme present. Generally, a high WBC with increased neutrophils is associated with increased enzyme.

6. One hundred consecutive band & segmented neutrophils are rated 0-4+ on the basis of the quantity & intensity of the precipitated red dye in their cytoplasm. 6. How are the cells graded? The sum of the ratings of 100 cells is the LAP score; the cell ratings and total score are reported. 6. What is a normal score? A normal LAP score is 13-130 (established by institution). Healthy individuals have a normal score.

7. 0 • On the LAP control slide, cells were rated as follows: 0 20 = 1+ 60 = 2+ 20 = What is your next step? (Select one) 60 Total LAP score = 100 40 a. Count the patient LAP slide. b. Repeat stain with a new control and fresh reagents. The control score is not within the acceptable range (>140) for this procedure. Check that procedure protocol was followed.

8. 8. State the expected LAP score (Increased, Decreased, or Normal) for the following conditions: I Primary polycythemia Secondary polycythemia CML and Hodgkin’s lymphoma in remission Paroxysmal nocturnal hemoglobinuria Bacterial septicemia Late pregnancy N N D I I

9. 9. A STAT LAP is ordered on a 5-year-old male with a WBC of 8.5 K/µL and a differential of 20 segs-5 bands-70 lymphs-5 monos. Should you question this order? An LAP does not appear to be indicated. The CBC/diff results are normal for a 5-year-old. The leukocyte alkaline phosphatase order should probably be an alkaline phosphatase order.

10. You are now ready to perform a Leukocyte Alkaline Phosphatase count/interpretation on the case slides provided and report your results on the lavender worksheet found in the Special Tests Unit of the Hemo II manual.