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leukocyte alkaline phosphatase (LAP)
Indications:
-> principal utility is in distinguishing chronic myelogenous leukemia (CML) from leukemoid reactions & other myelo- proliferative disorders
Specimen:
1) finger-stick preferred
2) collect venous blood in heparin or oxalate; do NOT use EDTA
3) fix slides in formalin/methanol within 30 minutes or keep in dessicator until fixed
Reference values:
1) 15-40 mg of phosphorous liberated/hour per 10E10 cells
2) score 13-130 per 100 neutrophils & band forms (score determined by individual laboratory)
Methods:
1) Kaplow
2) napthol AS-BI phosphate
3) fast red-violet LB
Decreases: (Low or absent in)
1) 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
2) pharmaceutical agents
- chemical interference
- EDTA
Increases:
1) 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 [3]
- bacterial infection
2) pharmaceutical agents
- in vivo effects
- ACTH
* In remission of CML, LAP may return to normal & may be elevated with CML in blast crisis [3]
alkaline phosphatase-L (liver/kidney/bone) or tissue-nonspecific alkaline phosphatase
Related
alkaline phosphatase-L (liver/kidney/bone, tissue-nonspecific alkaline phosphatase, ALPL)
General
clinical hematology test
References
- Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed)
Lippincott-Raven, Philadelphia, 1998, pg 433, 435
- Medical Knowledge Self Assessment Program (MKSAP) 11, American
College of Physicians, Philadelphia 1998
- Clinical Guide to Laboratory Tests, 3rd ed. Teitz ed.,
W.B. Saunders, 1995