LEUKOCYTE ALKALINE PHOSPHATASE STAIN (089-3115)

Synonyms: LAP, Leukocyte Alkaline Phosphatase, LAP score

CPT 4 Code:  85540

Test Order Mnemonic: LEUKAP

Applies To: Differentiates leukemoid reaction from Chronic Myelogenous Leukemia.

Lab: Hematopathology

Request Form: Hematology A

Collection: Collect in EDTA. Invert promptly to prevent clotting.

Storage Instructions: Specimen must be delivered to Hematopathology (5.142 McCullough) within 30 minutes of collection.

Cause For Rejection: QNS, old specimen, identification errors, receipt in lab after hours unless prior arrangement made.

Availability: Test must be scheduled with lab. Available from 8 AM - 1 PM, Monday-Friday.

Turnaround Time: 48 hours

Special Instructions: Test must be approved by Hematopathologist or Hematology/Oncology Faculty Member. Smears must be prepared within one hour of collection. Prompt delivery to lab is critical.

Specimen: Blood

Volume: 2.0 ml

Minimum Volume: 1.0 ml

Container: EDTA (Lavender-top tube)

Reference Ranges: Adults: 40-120. Patients with CML generally have a decreased LAP score (0-15). Elevated levels (>180) seen in leukemoid reaction, stress, polycythemia vera, myeloid metaplasia, glucocorticoid administration and third trimester of pregnancy.

Test Method: Cytochemical hydrolysis of naphthol ASBI phosphate (modified by Kaplow); manual microscopy.

Interfering Substances: Inappropriate fixatives or anticoagulants, clotted specimen.

Revised 10/10/07 by L. Dornak, MT(ASCP)