leukocyte alkaline phosphatase (LAP)

Indications

• principal utility is in distinguishing chronic myelogenous leukemia (CML) from leukemoid reactions & other myelo- proliferative disorders

Reference interval

• 15-40 mg of phosphorous liberated/hour per 10E10 cells
• score 13-130 per 100 neutrophils & band forms (score determined by individual laboratory)

Increases

• clinical disorders
  • polycythemia rubra vera (highest values)
  • leukemoid reactions
  • agnogenic myeloid metaplasia
  • idiopathic thrombocytopenic purpura
  • Down's syndrome
  • stress
  • pregnancy
  • myeloproliferative disorders
  • acute lymphoblastic leukemia
  • Hodgkin's disease
  • aplastic anemia
  • bacterial infection
• pharmaceutical agents
  • in vivo effects
    • ACTH

* In remission of CML, LAP may return to normal & may be elevated with CML in blast crisis

alkaline phosphatase-L (liver/kidney/bone) or tissue-nonspecific alkaline phosphatase

Decreases

(Low or absent in)

• clinical disorders
  • chronic myeloid leukemia (CML)*
  • paroxysmal nocturnal hemoglobinuria (PNH)
  • infectious mononucleosis
  • aplastic anemia [1, 2]
  • sideroblastic anemia
  • idiopathic thrombocytopenic purpura (ITP)
  • connective tissue disorders
  • acute myeloid leukemia
  • acute monocytic leukemia
  • cirrhosis
  • congestive heart failure with passive liver congestion
  • diabetes mellitus
  • gout
  • pernicious anemia (increases after treatment)
  • hereditary hypophosphatemia
  • sarcoidosis
• pharmaceutical agents
  • chemical interference
    • EDTA

Methods

• Kaplow
• napthol AS-BI phosphate
• fast red-violet LB

Specimen

• finger-stick preferred
• collect venous blood in heparin or oxalate; do NOT use EDTA
• fix slides in formalin/methanol within 30 minutes or keep in dessicator until fixed

More general terms

• clinical hematology test

Additional terms

• alkaline phosphatase-L (liver/kidney/bone, tissue-nonspecific alkaline phosphatase, ALPL)