(18) ALP - LIVER ENZYMES Flashcards
ALP aka
Alkaline Orthophosphoric monoester phosphohydrolase
- Catalyze the hydrolysis of various phosphomonoesters at an alkaline pH
- Liberate inorganic phosphate from an organic phosphate ester with production of alcohol
ALP (Alkaline phosphatase)
ALP activator
Mg2+
Most of ALP in healthy human sera are derived from
liver & bones (specifically osteoblast)
ALP Major tissue sources:
o Liver, Bones, Placenta, Intestine, Kidneys
ALP Major tissue sources:
o Liver, Bones, Placenta, Intestine, Kidneys
NOTE:
ALP Diagnostic significance:
o For evaluation of hepatobiliary & bone disorders.
- Assay for Enzyme Activity for ALPs
- Based on molar absorptivity of p-Nitrophenol
- Absorbance is measured @ 405nm
Bowers & McComb
Bessy, Lowry & Brock
Bowers & McComb
ALP SUBSTRATE: p-nitrophenyl phosphate
ALP END PRODUCT: p-nitrophenol (yellow)
ALP SUBSTRATE: B-glycero-phosphate
ALP END PRODUCT: Inorganic PO4
Glycerol
Bodansky method
Shinowara method
Jones method
Reinhart method
King & Armstrong
ALP SUBSTRATE: Phenyl Phosphate
ALP END PRODUCT: Phenol
ALP isoenzymes are differentiated thru
Electrophoresis
- fastest isoenzyme to migrate; most anodic
- ↑in hepatobiliary disorder / liver dsz
Liver ALP
contributes to the abundance of ALP among healthy individual.
Major liver band
responsible for the fast migration
Fast liver (a1) band
- 2nd fastest to migrate
- Heat labile fraction
o ↑temp = ↓ bone ALP activity
o Significant ↓ @56°C
Bone ALP
- ↑ in bone dsz (pathologic cause), healing of bone & fractures physiologic bone growth
o ↑↑ in Paget’s dsz (osteitis deformans)
Bone ALP
- Most heat-stable fraction
- ↑in pregnancy on 16th-20th wk of gestation
- Associated w/ malignancy → Carcinoplacental ALP
Placental ALP
- Most heat-stable fraction
- ↑in pregnancy on 16th-20th wk of gestation
- Associated w/ malignancy → Carcinoplacental ALP
Placental ALP
- slowest isoenzyme to migrate; least anodic
- ↑ on certain blood groups
o Type B or O secretors: ↑ALP secretions (physiologic cause) - ↑ in fatty meal consumption
- ↑intestinal ALP: pathologic conditions in the GIT
Intestinal ALP
Chemical inhibitor of Placental & intestinal ALP
Phenylalanine
Chemical inhibitor for bone ALP
3M Urea reagent
Chemical inhibitor for bone & liver ALP
Levamisole
Inhibits activity of certain enzymes so that specific isoenzyme is measured.
Chemical inhibitors
Total ALP elevations by liver or Bone ALP is differentiated by heating of serum at
56°C for 10mins
differentiates bone ALP as cause of elevation of ALP in serum
Heat stability test
Most heat-stable to least isoenzyme:
P> I > L > B
most heat-stable
Placenta
most heat-labile
Bone
After heating ALP isoenzymes are surely ↓ but:
- Liver ALP
o ALP residual activity is ↓to >20% activity - Bone ALP
o ALP residual activity is ↓ to <20% activity
NOTE: ALP
Probable ALP present in 1 & 4 is probably LIVER (bcos >20%)
▪ Lung, Breast, & gynecological CA, bone ALP co-migrator
▪ Most heat stable ALP
* Can remain stable even though u heat it at 65°C for 30mins
Regan ALP
▪ Adenocarcinoma of the Pancreas & Bile duct, Pleural CA
Nagao ALP
Carcinoplacental ALP Inhibitors:
Phenylalanine : Can inhibit Nagao and Regan
L-leucine : Can inhibit Nagao
stage where there’s growth hormone surge
Puberty
most active in bone growth which also increases ALP levels.
Osteoblast
Reference range ng ALP
refer to handout (page 13)
