alkaline phosphatase (ALP) in serum/plasma

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Indications

Reference interval

  • Male & Female:
    • adult: 32-116 U/L
    • birth: 36-107 U/L
    • 1 month: 71-213 U/L
    • 3 years: 71-142 U/L
    • 10 years: 107-213 U/L

Principle

The Kodak Ektachem Clinical Chemistry Slide (ALKP) quantitatively measures alkaline phosphatase activity in serum or plasma.

The Kodak Ektachem Clinical Chemistry Slide (ALKP) is a dry, multilayered analytical element coated on a clear polyester support. It is also a MULTIPLE-POINT RATE test.

An 11 uL drop of sample is deposited on the slide. The spreading layer also contains the p-nitrophenyl phosphate substrate & other components needed for the reaction. The ALKP in the sample catalyzes the hydrolysis of the p-nitrophenyl phosphate1 to p-nitrophenol at alkaline pH. The p-nitrophenol, which is yellow, then diffuses into the underlying layer where it is monitored by reflectance spectrophotometry. The rate of change in reflection density is then converted to enzyme activity.

The assay time for ALKP is approximately 5 minutes at 37 C.

The following reaction sequence is involved:

p-Nitrophenyl phosphate --------------> p-Nitrophenol + H3PO4

Clinical significance

Serum alkaline phosphatase measurements are of particular interest in the investigation of hepatobiliary disease & bone disease associated with increased osteoblastic activity.

Alkaline phosphatase is elevated in liver disease with cholestasis. Liver diseases that principally affect parenchymal cells, such as infectious hepatitis, typically also show only moderately (less than threefold) elevated or even normal serum alkaline phosphatase levels.

In bone disease the alkaline phosphatase is increased in those conditions in which bone regeneration is taking place. It is not found when there is bone destruction unless there is simultaneous formation of new bone or osteoid tissue.

Alkaline phosphatase is present mainly in bone, liver, kidney, intestine, placenta, & lung. ALKP is present in practically all tissues of the body especially at or in the cell membrane.

Increases

* serum gamma-glutamyltransferase if serum alkaline phosphatase is elevated

* bone scintigraphy if isolated elevation of serum alkaline phosphatase with normal serum gamma-glutamyltransferase

Decreases

Specimen

No special patient preparation is required.

For serum preparation: Collect the specimen by the standard venipuncture technique. Specimens are collected in a red top vacutainer by venipuncture & allowed to clot. Remove serum promptly from the clot. Hemolyzed specimens should not be used.

Heparin may be used as an anticoagulant for plasma specimens.

Minimum sample size of 0.5 milliliter: with an optimum size of 1.0 mL or larger.

Samples that have ALKP values that exceed the analyzer's dynamic range, should be diluted with Kodak Ektachem Solution (7% BSA)/Bovine Serum Albumin & reanalyzed. Multiply results by the dilution factor to obtain the original sample's ALKP activity.

More general terms

More specific terms

Additional terms

Component of

References

  1. Tietz, N., Fundamentals of Clinical Chemistry, 3rd Edition, W.B. Saunders Company, Philadelphia, 1987, p.386-387.
  2. Bauer, J./Ackerman,P./Toro,G., Clinical Laboratory Methods, 8th Edition, C.V. Mosby Company, St. Louis. MO., 1984, p.492.
  3. Kodak Ektachem 700 Analyzer Operator's Manual, Kodak Clinical Products Division, Eastman Kodak Company, Rochester, New York.
  4. Package Insert, Kodak Ektachem Clinical Chemistry Product, Eastman Kodak Company, Rochester, New York.
  5. Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 10.
  6. Clinical Guide to Laboratory Tests, 3rd ed. Teitz ed., W.B. Saunders, 1995
  7. Alkaline Phosphatase Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0020005.jsp
    Panel of 15 tests Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0020408.jsp
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    Panel of 3 tests Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0000000.jsp
  8. 8.0 8.1 Medical Knowledge Self Assessment Program (MKSAP) 19. American College of Physicians, Philadelphia 2021

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