Function of alkaline phosphatase (ALP)
liberates phosphate while producing an ester
Where is ALP found
liver, bone, placenta, intestine, spleen, cell surfaces
significance of ALP
detection of bone and liver diseases (high amounts = biliary obstruction)
How much is ALP elevated in hepatic jaundice
3x
How much is ALP elevated in post hepatic jaundice
10x
What do osteoblasts do and what do they release?
They build bone, and release ALP
What bone disorders are associated with decreased ALP?
Hypothyroidism, scurvy, hypophosphatemia, protein deficiency, cretinism, severe anemia
What bone disorders are associated with increased ALP?
Paget's disease, Vit D deficiency, hyperparathyroidism, acromegaly, bone fractures
What intestinal diseases are associated with increased ALP?
artery embolism, uremic state, cirrhosis, perforation of bowel, ulcerative diseases
When is placental ALP increased?
infraction of placenta, typhoid fever, preeclampsia, hypertension, threatened abortion (also used as tumor marker)
When is peritoneal ALP increased?
Damage to small intestines
order of ALP isoenzymes in electrophoresis (fastest to slowest)
liver-bone-spleen-placenta-intestinal
What ALP isoenzymes does L-phenylalanine NOT inhibit?
liver and bone
Order or ALP denaturing by urea
bone-liver-intestine-placenta
Activators for ALP
Mg, Co, Mn, Zn
Inhibitors for ALP
Phosphate, borate, EDTA, citrate, oxalate, cyanide ions, calcium, acidic or neutral pH
Bowers and Mccomb reaction
uses p-nitrophenylphosphate and ALP to produce p-nitrophenol (yellow color)
Reference range of ALP
30-90 U/L
What type of specimens can be used for ALP measurement?
serum or lithium heparin (NO citrate, oxalate, or EDTA)
Why does hemolysis increase ALP levels?
ALP on cell surface
Function of acid phosphatase
hydrolyzes orthophosphoric monoesters into inorganic phosphate and alcohol
Location of acid phosphatase
lysosomes, osteoclastic cells of bone
ACP rr
0-3.5 ng/mL
Clinical significance of ACP
prostate disease or bone malignancy
Prostatic acid phosphatase
increased in 75% of males with prostate cancer
Prostate specific antigen
elevated along with PAP; specific for prostate tissue (not the cancer), monitors successful treatment
Substrates used for PAP measurement
Thymolphthalein monophosphate Alpha-napthyl-phosphate
Difference between ALP and PAP Bower Mccomb assay
PAP is done at a pH of 5
What inhibits PAP?
tartrate (difference is calculated and used to determine amount of PAP) total ACP - inhibited ACP = PAP
Is ALP and ACP affected by bilirubin?
ACP is not, ALP is (bc bilirubin is absorbed at same wavelength)
How is ACP affected by hemolysis?
RBC activity increases ACP
Can ACP survive long at room temp?
No, but ALP can
Purpose of ACP activity scans in vaginal fluid
rape cases
Amylase purpose
breaks down starch via hydrolysis
Two types of amylase
beta (plant and bacterial) and alpha (human)
Two isoenzymes of alpha amylase
P-amylase (from acinar cells of pancreas) S-amylase (salivary glands)
Clinical significance of amylase
diagnosis acute pancreatitis
Why is amylase measured through urine?
Very small; able to be filtered
Macroamylasemia
This condition causes elevated serum amylase because it binds to cold agglutinins and the resulting complex is too big to be filtered in the glomerulus:diagnosed with amylase: creatinine ratio
Types of AMY methodologies
Saccharogenic, Amyloclastic, Chromogenic, Enzymatic
Saccharogenic method
measures the activity of AMY though how much maltose is reduced
Amyloclastic method
Measures the disappearance of starch as it is broken down to reduce sugars through amylase activity. Starch is dyed blue and loses color when broken down
Chromogenic assay
Dye holding substrates release dye when hydrolyzed by AMY
Enzymatic procedure
Maltotetraose reaction and matrapentose reaction. Rate production of NADH proportional to AMY
Interferences of AMY
saliva (elevates), wheat germ lectin (inhibits), morphine and opiates (elevates), chloride ion (must be present)
Inhibitors of AMY
citrate, EDTA, oxalate
Activators of AMY
calcium, chloride, bromide, nitrate, chlorate HPO4
Is AMY affected by hemolysis?
no
AMY rrs
serum: 30-100 U/L urine: 1-7U/L
Lipase function
hydrolyzes glycerol esters into fatty acids and alcohol
clinically significant lipase
pancreatic lipase
Is lipase filtered by kidney?
yes
Is lipase found in urine?
no
How is the lipase/AMY assay used?
To distinguish AMY levels from salivary from pancreatic (lipase elevated=pancreatic)
Enzymatic reaction rate diglyceride assay
Used for lipase levels. Produces peroxidase which reacts with TOOS, producing a color
Inhibitors of lipase
heavy metals, quinine, esterase inhibitors
Lipase rr
<45 U/L
Cholinesterase function
hydrolyzes choline ester into choline and fatty acids
Two types of cholinesterase
acetylcholinesterase and butyrylcholinesterase
What does a decrease in CHE indicate
decreased liver function
Clinical significance of TRY
important for screening of cystic fibrosis and chronic pancreatitis. measured in stool
TRY methodology
2x dilution made from barbitual buffer, incubate for 30 min and check for digestion of gelatin (indicating enzyme activity)