Leukocyte Alkaline Phosphatase Stain (LAP)

LAP: A Test That Time Has Passed By

September 2010

Today we will be talking about leukocyte alkaline phosphatase stain, or LAP, as a test that time has truly passed by. Occasionally the LAP may be confused with other tests. The LAP is not a serum alkaline phosphatase which is used to evaluate liver, bone, intestinal, and other diseases. Another test that is sometimes mistakenly confused with the LAP is leucine aminopeptidase. This enzyme is marketed as a potential useful marker of hepatic function and may be abnormal in some cancers. Both of these assays may be the intended goal of the clinician, but by mistake, a LAP is ordered instead.

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A Test That Time Has Passed By

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Jump to section:

• Introduction
• Optimizing Laboratory Testing for Hematologic Disorders Series
• The Big Picture: We Need to Focus On...
• LAP: A Test That Time Has Passed By
• Abbreviations
• LAP: Assay History
• LAP: Original Clinical Utility
• LAP Procedure—an Inexact Science!
• Typical Staining Type Reaction
• Subjective Nature of the Scoring Process
• LAP Scoring Example
• LAP Discontinued at Mayo Clinic
• Low LAP Scores* Not Specific for CML: A Mayo 1-Year Experience
• Low LAP Scores* Do Not Indicate Myeloid Malignancy: A Mayo 1-Year Experience
• High LAP Scores* Not Specific for PV: A Mayo 1-Year Experience
• High LAP Scores* Do Not Indicate Myeloid Malignancy: A Mayo 1-Year Experience
• LAP: A Test Whose Time Has Passed
• Consequences of an Abnormal LAP
• Alternatives to LAP
• Alternatives to LAP: BCR/ABL
• Alternatives to LAP: JAK2
• Conclusions
• Questions?