SEM 1 - (CC) LIVER FUNCTION TEST 3 Flashcards
It involves enzyme and ammonia tests.
TEST FOR DETOXIFICATION FUNCTION
Any injury to the liver that results in cytolysis and necrosis causes the ______ of various enzymes.
liberation
______ are often the only indication of cell injury in early or localized liver disease.
Enzyme tests
The ______________ are mostly assessed when there is hepatocellular injury caused by toxins such as drugs and alcohol.
aminotransferases (ALT and AST)
Both ALT and AST are increased in ______ and ________ with ___ having higher plasma levels.
drug and alcohol hepatoxicity ; AST
It arises from the deamination of amino acids, which occursmainly through the action of digestive and bacterial enzymes (bacterial proteases, ureases, and amine oxidases) on proteins in the intestinal tract.
Ammonia
It is only metabolized in the liver through the enzymes of the Krebs-Henseleit or urea cycle.
Ammonia
The liver normally removes most of this NPN via the portal vein circulation and converts it to urea which is then eliminated by the kidneys (urine)
Ammonia
_____ is the only organ responsible for ammonia detoxification via the urea cycle.
Liver
also released from metabolic reactions that occur in skeletal muscles during exercise
Ammonia
what are the disease associated with increased levels of Ammonia?
Cirrhosis, hepatitis, Reye’s syndrome, chronic renal disease, and acetaminophen poisoning
ref. range for Ammonia
19-60 ug/dL (11-35 mmol/L)
Diagnostic Significance of Ammonia(NH3)
- For the diagnosis of _______ (hepatic coma) and _______
hepatic failure and Reye’s Syndrome
In severe liver disorder, NH3 accumulates and reaches the systemic circulation, which is then converted to ______ in the brain, thus compromising the Kreb’s cycle leading to ____due to lack of ATP for the brain.
glutamine ; coma `
An elevated plasma NH3 is _______ and is often associated with _____
neurotoxic ; encelopathy
An important mechanism by which ammonia can cause toxicity to the CNS is its ability to lower the concentration of ____________, a crucial neurotransmitter in the CNS, by reacting with
glutamic acid producing glutamine via reversal of the glutaminase-catalyzed reaction.
gamma-aminobutyric acid (GABA)
Ammonia also increases central nervous system ___ environment
pH
Plasma levels of ammonia, though an NPN, are not dependent on renal function but on _______, thus, NH3 is not useful in the study of kidney diseases.
liver function
In panhepatic cirrhosis, there is 80% loss of hepatocytic function, thus plasma ammonia is _______
elevated
(Measurement of Ammonia)
______ is a source of contamination which leads to false elevated concentrations.
Smoking
(Measurement of Ammonia)
Prolonged standing of the specimen increases ammonia level due to enzymatic deamination of labile amides such as ______
glutamine
(Measurement of Ammonia)
Preferred sample: ______
Arterial blood
(Measurement of Ammonia)
Sample requirement:
Heparin or EDTA plasma (sample kept in ice water immediately)
(Measurement of Ammonia)
Common method:
Glutamate Dehydrogenase
(Measurement of Ammonia)
Major interference:
Hemoglobin (avoid hemolyzed blood, false increased)
(Measurement of Ammonia)
Venous blood may be considered as an alternative to arterial blood, provided, tourniquet application should be less than ___ minute without repeated ______ prior to and during sample collection.
one ; fist clenching
(Measurement of Ammonia)
Specimens should be kept in ___ water until separation of cells from plasma occurs
ice
Nitrogen ion in a protein-free filtrate (PFF) of the specimen is converted to ammonia using hot concentrated sulfuric acid in the presence of catalyst.
Digestion (Kjeldahl) Method
Digestion (Kjeldahl) Method
Catalyst:
Copper sulfate, mercury, and selenium
Nesslerization Reaction
symbol of Dimercuric potassiumiodid
K2Hg2I2:
Nesslerization Reaction
___ end color: Nitrogen content in the sample is low to moderate
______ end color: Nitrogencontentis high
Yellow
Orange brown
itis currently the most commonly method formeasurement of ammonia.
It involves the formation of Schiff base between ammonia and the alpha-keto
producing glutamine which is primary amine at 340 group of alpha-ketoglutarate, then
NH3 + a-ketoglutarate + NADPH Pathophysiology of Hepatic Cirrhosis
nm in the presence of GLDH.
Glutamate Dehydrogenase (GLDH)
(Pathophysiology of Hepatic Cirrhosis)
__________ is the terminal phase of hepatic injuries that make the liver ineffective at completing all the vital fuctions.
liver cirrhosis
(Pathophysiology of Hepatic Cirrhosis)
It rarely causes signs and symptoms in its inception, but as liver function deteriorates, all the clinical manifestations are evident.
Hepatic Cirrhosis
It is a clinical condition in which a scar tissue replaces a normal, healthy liver tissue.
Hepatic Cirrhosis
