SERUM TRIGLYCERIDE TEST Flashcards
______ are ubiquitous in the body tissue and have an important role in virtually all aspects of life-serving as
hormones or hormone precursors
aiding in digestion
providing energy storage and metabolic fuels
acting as functional and structural components in cell membranes
forming insulation to allow nerve conduction or to prevent heat loss
Lipids
The term lipid applies to a class of compounds that are soluble in _____ and nearly insoluble in____.
organic solvents
water
lipids are either compound that yields_____ on hydrolysis or
complex alcohols that combine with fatty acids to form_____.
fatty acid
esters
Some lipids are more complex, containing non-lipid groups, such as (4).
The presence of these groups gives them the property (_____) of having an affinity for both water and organic solvents, which is important in the formation of membranes.
sialic, phosphoryl, amino, or sulfate groups
amphipathic
CLASSIFICATION OF CLINICALLY IMPORTANT LIPIDS
Sterol derivatives
Fatty acids
Glycerol esters
Sphingosine derivatives
Terpenes
Sterol Derivatives
• Cholesterol and cholesteryl esters
• Steroid hormones
• Bile acids
• Vitamin D
Fatty Acids
• Short chain (2 - 4 carbon atoms;
• Medium chain (6 - 10 carbon atoms)
• Long chain (12 - 26 carbon atoms)
• Prostaglandins
Fatty acids
• Short chain
• Medium chain
• Long chain
• Prostaglandins
2 - 4 carbon atoms
6 - 10 carbon atoms
12 - 26 carbon atoms
Glycerol Esters
• Tri-, Di-, and Monoglycerides (acylglycerols)
• Phosphoglycerides
Sphingosine Derivatives
• Sphingomyelin
• Glycosphingolipids
Terpenes (Isoprene Polymers)
• Vitamin A
• Vitamin E
• Vitamin K
GLYCEROL ESTERS also known as
ACYLGLYCEROLS
Virtually all the complex lipids are fatty acid derivatives, and in most cases, they are covalently linked to an alcohol.
One of the most common alcohols found in human metabolism is____, a three-carbon molecule containing three______
glycerol
hydroxyl groups
The two terminal carbon atoms in the molecule are chemically equivalent and are designated a and a’.
The center a carbon is labeled B.
Glycerol esters
The class of acylglycerol (glyceride) is determined by the number of_______ present;
one fatty acid, monoacylglycerols (monoglycerides)
two fatty acids, diacylglycerols (diglycerides)
three fatty acids, triacylglycerols (triglycerides)
fatty acyl groups
In human nutrition,______ are the most prevalent glycerol esters encountered and constitute____% of tissue storage fat and are the predominant form of glyceryl ester found in plasma.
triglycerides
95%
Triglycerides from _____ tend to have large amounts of C18:2 or_____ residues and are liquid at room temperature.
plants (e.g., com, sunflower seed, and safflower oils)
linoleic
Triglycerides from_____, especially ruminants, tend to have C12:0 through C18:0 fatty acid residues (saturated fats) and are solids at room temperature.
animals
Some plant triglycerides, such as_______, are highly saturated and may be solid at room temperature.
coconut oil
Triglycerides are digested in the
duodenum and proximal ileum
Through the action of _____and _____ and in the presence of_____, they are hydrolyzed to glycerol, monoglycerides, and fatty acids.
pancreatic and intestinal lipases
bile acids
After absorption, triglycerides are resynthesized in the______ and combined with cholesterol and apo B-48 to form_______.
intestinal epithelial cells
chylomicrons
(2) are important indicators of CHD (coronary heart disease) risk, which is a major reason for their measurement in research, as well as in clinical practice.
Lipids and lipoproteins
The triglyceride value is also commonly used in the estimation of LDL cholesterol by the_____
Friedewald equation
1
Several enzymatic reaction sequences are available for triglyceride measurement, all including_____ to cleave fatty acids from the glycerol backbone.
The freed glycerol participates in any one of several enzymatic sequences.
One of the more common earlier reactions, ending in a product measured in the ultraviolet (UV) region, used glycerol kinase and pyruvate kinase, culminating in the conversion of NADH to NAD+ with an associated decrease in absorbance.
lipases
2
This reaction #1 is susceptible to interference and side reactions. The UV endpoint is also less convenient for modern analyzers, so this and other UV reaction sequences have been replaced by a second sequence, involving glycerol kinase and glycerol-phosphate oxidase coupled to the same peroxidase ____ reaction described for cholesterol.
color
In most specimens, the endogenous free glycerol contributes a _____ overestimation of triglycerides.
10 - 20 mg/dL
About_____% of specimens will have higher glycerol, with levels increased in certain conditions, such as diabetes and liver disease or from glycerol containing medications.
20%
Reagents are available that correct for______ and are used by many research laboratories, but such methods are less efficient, and hence uncommon in clinical laboratories
endogenous free glycerol
The triglyceride reference method involves (3) an assay that is tedious, poorly characterized, and only applied in the lipid standardization laboratory at the Centers for Disease Control and Prevention (CDC) and a few other standardization laboratories.
alkaline hydrolysis
solvent extraction
a color reaction with chromotropic acid
