alkaline phosphatase (ALP) in serum/plasma

Indications

• evaluation of bone disease (osteoblast activity)
  • healing of a bone fracture
  • hyperparathyroidism
  • osteomalacia
  • juvenile rickets
  • metastatic carcinoma in bone
  • osteogenic sarcoma
  • multiple myeloma
  • bone involvement in Hodgkin's disease
  • Gaucher's disease with bone resorption
  • Paget's disease
  • Cushing's syndrome
  • osteodystrophy
  • renal tubular disorders
• evaluation of liver disease
  • infectious mononucleosis
  • extrahepatic biliary obstruction (> 3-fold)
  • cytomegalovirus infection in infants
  • cholangitis
    • primary biliary cholangitis/primary biliary cirrhosis (women)
    • primary sclerosing cholangitis (young men)
  • cholangiolitis
  • hepatocellular necrosis (< 3-fold)
  • portal cirrhosis (some)
  • liver abscess
  • hepatocellular carcinoma
  • liver regeneration
  • hepatocellular nodules
    • metastatic tumor, heaptic cyst, parasitic infection, amyloid, tuberculosis, sarcoidosis, leukemia
  • hepatitis -right heart failure
• evaluation of extrahepatic biliary obstruction

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

• *clinical disorders
  • *increased bone metabolism
    • healing of a bone fracture
    • hyperparathyroidism
    • osteomalacia
    • juvenile rickets
    • metastatic carcinoma in bone
    • osteogenic sarcoma
    • multiple myeloma
    • bone involvement in Hodgkin's disease
    • Gaucher's disease with bone resorption
    • Paget's disease
    • Cushing's syndrome
    • uremic osteodystrophy
    • renal tubular disorders
  • *liver disease
    • infectious mononucleosis
    • extrahepatic biliary obstruction (> 3-fold)
    • cytomegalovirus infection in infants
    • cholangitis
      • primary biliary cholangitis/primary biliary cirrhosis
      • isolated increase in serum ALP with normal to near normal serum AST, serum ALT & bilirubin suggests cholangitis thus testing for mitochrondial antibody indicated (women)
    • cholangiolitis
    • hepatocellular necrosis (< 3-fold)
    • portal cirrhosis (some)
    • liver abscess
    • hepatocellular carcinoma
    • liver regeneration
    • hepatocellular nodules (metastatic tumor, cyst, parasitic infection, amyloid, tuberculosis, sarcoidosis, leukemia)
    • hepatitis
    • right heart failure
  • *miscellaneous
    • extrahepatic sepsis
    • ulcerative colitis
    • regional enteritis
    • intra-abdominal bacterial infections
    • thyrotoxicosis
    • benign transient hyperphosphatemia (children)
    • pulmonary infarction
    • renal infarction
    • pancreatitis
• *pharmaceutical agents:
  • *in vivo effects
    • *see drugs that may affect liver function tests
    • acebutolol, aminoglutethimide, aminoglycosides, bromocryptine, carboplatin, captopril, cephalosporins, clindamycin, clotrimazole, colchicine, cyclosporine, cytarabine, dapsone, desipramine, dicumarol, didanosine, disopyramide, enalapril, ethambutol, etoposide, filgastim, flucytosine, foscarnet, ganciclovir, gentamicin, interferon, isotretinoin, ketoconazole, labetalol, levamisole, lincomycin, mebendazole, mephenytoin, nifedipine, NSAIDs (ibuprofen, naproxen), omeprazole, ondansetron, penicillins, phenytoin, propoxyphene, protriptyline, streptozocin, sulfonylureas, thioguanine, ticlopidine, verapamil, zalcitabine
  • *chemical interferences
    • *albumin from placental sources, ascorbate (high concentrations), magnesium

* serum gamma-glutamyltransferase if serum alkaline phosphatase is elevated

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

Decreases

• clinical disorders
  • hypothyroidism
  • scurvy
  • anemia
  • kwashiorkor
  • achondroplasia
  • cretinism
  • deposition of radioactive materials in bone
  • hypophosphatemia
  • pernicious anemia
  • magnesium deficiency
  • zinc deficiency
• pharmaceutical agents:
  • in vivo effects
    • azathioprine, clofibrate, danazol, estrogens
  • chemical interferences
    • arsenate, berylium, citrate, cyanide, EDTA, fluoride, manganese, oxalate, phosphate, sulfhydryl compounds, theophylline, zinc & magnesium salts

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

• alkaline phosphatase (ALP) in serum/plasma/blood
• liver (function) tests (LFT, liver panel, hepatic function panel)

More specific terms

• alkaline phosphatase (ALP) isozymes in serum/plasma
• alkaline phosphatase bile isozyme in serum
• alkaline phosphatase bone isozyme in serum
• alkaline phosphatase intestinal isozyme in serum
• alkaline phosphatase liver isozyme in serum
• alkaline phosphatase lung isozyme in serum
• alkaline phosphatase placental isozyme in serum
• alkaline phosphatase renal isozyme in serum
• alkaline phosphatase, heat labile in serum
• alkaline phosphatase, heat stable in serum

Additional terms

• alkaline phosphatase-L (liver/kidney/bone, tissue-nonspecific alkaline phosphatase, ALPL)
• drugs that may affect liver function tests (LFTs)

Component of

• chemistry 14 panel (comprehensive metabolic panel, CMP, chem 12, SMA12, SMA20)
• parathyroid panel
• liver (function) tests (LFT, liver panel, hepatic function panel)
• enteral/parenteral nutrition management panel
• bone/joint panel

Patient information

alkaline phosphatase in serum patient information