LEUKOCYTE ALKALINE PHOS SCORE

Test Code

1966

CPT Codes
85540

Includes

"Blood films are stained and 100 neutrophilic (segmented and band forms only) leukocytes are scored from 0 to 4+ on the basis of the intensity of the precipitated dye in their cytoplasm. The values of the 100 cells are added and the total score reported.

Preferred Specimen

"Smears made from fingerstick or heparinized specimen; heparin (green-top) tube - slides must be made within 24 hours of collection.
"

Minimum Volume

"Two freshly made blood films
"

Transport Container

"

Slides; green-top (heparin) tube - slides must be made within 24 hours of collection.
"

Transport Temperature

Room Temp

Specimen Stability

"Smears are to be maintained at room temperature for up to seven days
"

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

"

Improper labeling; heparin tube specimen more than 24 hours old; frozen slides; slides more than seven days old; slides made from any anticoagulant other than heparin
"

Methodology
"Enzyme reaction with leukocyte alkaline phosphatase liberating naphthol or a substituted naphthol compound which then couples with fast blue RR or other chromogen to form an insoluble precipitate. Color of the precipitate relates to the type of substituted naphthol substrate and diazonium dye used (color is reagent dependent). Cells are scored as to the degree of phosphatase activity present, 0 to 4+. One hundred cells are counted and the score totaled. "

Limitations

"

Pregnancy, increased number of immature forms of neutrophils, and postoperative or “stressful” states are associated with increased scores. The differential must have adequate numbers of mature neutrophilic granulocytes to perform the LAP.
"

Reference Range

"

25-130
"

Clinical Significance

"

Aids in the differential diagnosis of chronic myelocytic leukemia (CML) versus leukemoid reaction; aids in the evaluation of polycythemia vera, myelofibrosis with myeloid metaplasia, and paroxysmal nocturnal hemoglobinuria
"

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.