Alkaline phosphatase

Stains
Alkaline phosphatase

Author: Nat Pernick, M.D.

Topic Completed: 1 November 2013

Revised: 23 January 2020

Copyright: 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: alkaline phosphatase[title]

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Table of Contents

Cite this page: Pernick N. Alkaline phosphatase. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/stainsalkphos.html. Accessed April 8th, 2020.

Definition / general

Membrane bound glycoprotein with hepatic, osseous, renal and placental isoenzymes
See also PLAP-placental alkaline phosphatase
Tissue-nonspecific alkaline phosphatase (TNAP) plays a key role in bone mineralization by degrading inorganic pyrophosphate and providing free inorganic phosphate
TNAP gene defect causes hypophosphatasia, characteristic of systemic skeletal hypomineralization
Surgical pathology applications discussed below

Clinical features

May be affected by ABO loci and obesity (BMC Genomics 2013;14:684)
Elevated alkaline phosphatase screens for Vitamin D deficiency, although rarely alkaline phosphatase is normal (Clin Pediatr Endocrinol 2013;22:73)
Bone alkaline phosphatase is associated with acute myocardial infarction in a population with high prevalence of hypovitaminosis D (Clin Chim Acta 2013;425:192)
May predict outcome in alcoholic hepatitis (Biomed Res Int 2013;2013:614081)
Higher serum levels in patients with chronic kidney disease stages 3-4 are associated with higher mortality and end stage renal disease (Am J Kidney Dis 2013;62:703)

Uses by pathologists

Component of an alternative method in immunohistochemistry, click here
Muscle biopsies uses an enzymatic technique
- Use frozen tissue (protocol from IHC World)
- In inflammatory myopathies, appears to “spill out” from capillaries into interstitium due to increased vascular permeability
- Also a marker for regenerating myofibers
Osteoblasts (active)
- Often labeled using naphthol phosphate and the diazonium dye fast blue to demonstrate alkaline phosphatase enzyme activity directly, present on apical (secretory) cell membrane
- Confirms diagnosis of giant cell tumor of bone (Virchows Arch A Pathol Anat Histol 1978;378:287)

Microscopic (histologic) images

Images hosted on other servers:

Muscle: various images

Muscle: immature
small fibers have
cytoplasmic staining

Positive staining - normal

Cardiac muscle, smooth muscle
Endothelial cells: sites of alkaline phophatase activity appear red, nuclei stain blue
Osteoblasts

Positive staining - disease

Giant cell tumor of bone and soft tissue, mononuclear stromal cells (Hum Pathol 2005;36:945)
Muscle: regenerating fibers, immature muscle fibers, proliferative connective tissues