Bishop Chapter 11 Amino Acids and Proteins Flashcards
The two major groups of plasma proteins
Albumin and Globulins
Analysis of blood specimens will typically include what four protein measurements?
Total protein, albumin, globulins, and albumin-to-globulin ratio (A/G) ratio.
What is the alternative name for prealbumin?
Transthyretin
What is the reason for giving transthyretin the name prealbumin?
It migrates before albumin in classic serum protein electrophoresis (SPE).
Prealbumin acts as a transport protein for which thyroid hormone(s)?
Thyroxine and Triiodothyronine
Prealbumin forms a complex with which vitamin for transport?
Forms a complex with retinol-binding protein for transport of retinol (Vitamin A).
Prealbumin is rich with which amino acid?
Tryptophan
What would cause a decrease in serum prealbumin?
Hepatic damage due to decreased protein synthesis, during an acute-inflammatory response, or as a result of tissue necrosis.
How would poor nutritional status effect prealbumin?
Low prealbumin level
When would serum prealbumin be elevated?
Patients receiving steroid therapy, issues with alcohol abuse, or who are in chronic renal failure.
What protein is the most abundant in plasma?
Albumin
What is the rate at which albumin is synthesized?
9 to 12 g/day
What does albumin exist in other than in serum?
Extravascular (interstitial) space.
The total amount of extravascular albumin exceeds the total intravascular amount by how much?
30%
What is the transcapillary escape rate?
The rate at which intravascular albumin leaves the bloodstream per hour.
What is the clinical significance of albumin?
The transport of thyroid hormones, unconjugated bilirubin, fat-soluble hormones, iron, fatty acids, calcium, magnesium, and certain drugs such as aspirin.
Decreased blood concentrations of albumin are most commonly associated with what conditions?
Acute inflammatory response; liver disease; kidney disease.
What condition causes an increase excretion of albumin?
Nephrotic syndrome.
What is the clinical significance of high blood albumin?
Not clinically significant; can be the result of dehydration or excessive albumin infusion.
What is the main function of alpha1-Antitrypsin?
The inhibition of the protease, neutrophil elastase.
In which cells is neutrophil elastase released?
Leukocytes
How is the lack of alpha1-antitrypsin typically identified?
By the lack of alpha1-globulin band on serum protein electrophoresis.
What is the clinical significance of alpha1-fetoprotein?
Proposed that it protects the developing fetus from immunologic attack by the mother.
AFP can also be used as a tumor marker.
What is the primary function of haptoglobin?
To bind free hemoglobin to prevent the loss of its constituent, iron, into the urine.
Haptoglobin concentrations are primarily used to evaluate what condition?
Hemolytic anemia
If the haptoglobin concentration is normal and the reticulocyte count is increased, what is likely the cause of this?
Anemia is due to destruction of red blood cells in organs such as the spleen and liver.
If haptoglobin concentration are decreased without any sign of hemolytic anemia, what is the likely cause?
It is possible the liver is not producing adequate amounts of haptoglobin.
Ceruloplasmin is primarily measured along with what to diagnose Wilson’s disease?
Blood and urine copper tests.
What is Wilson’s disease?
An autosomal recessive inherited disorder associated with decreased concentrations of ceruloplasmin.
Decreased concentrations of ceruloplasmin can cause what condition(s)?
Hepatic cirrhosis and neurologic damage.
What is the clinical significance of transferrin?
Binds and transports iron to its storage sites (i.e. liver), where it is incorporated into apoferritin, which forms ferratin.
Transferrin concentrations are routinely measured to determine what conditions?
Anemia, gauge iron metabolism, and to determine the iron-carrying capacity of the blood.
Transferrin concentrations are abnormally elevated in what condition(s)?
Iron deficiency anemia.
Low transferrin concentrations can lead to what conditions?
Impair hemoglobin production which leads to anemia.
What precipitates in tissue as a result of inappropriate accumulation and precipitation of iron?
Hemosiderin
When does transferrin produce a low result?
Liver disease or not enough protein in the diet.
Define atransferrinemia.
An autosomal recessive trait due to mutation of both transferrin genes, with a resulting absence of transferrin.
How does iron deficiency effect the following analytes:
Total serum Iron, total iron-binding capacity, and transferrin saturation.
Total serum iron: DECREASED
Total iron-binding capacity: INCREASED
Transferrin saturation: DECREASED
Lipoproteins are complexes of proteins and lipids whose function is to do what?
Transport cholesterol, triglycerides, and phospholipids in the bloodstream.
What causes elevated serum levels for beta-2-microglobulin?
The result of impaired clearance by the kidney or overproduction of the protein that occurs in a number of inflammatory diseases.
The complement system is a natural defense mechanism that does what?
Protects the human body from infections.
What condition(s) are indicative of increased C3 and C4 levels?
Acute inflammatory disease and tissue inflammation.
What condition(s) are indicative to decreased levels of complement C3?
Autoimmune disease, neonatal respiratory distress syndrome, bacteremia, tissue injury, and chronic hepatitis.
What condition(s) are indicative of decrease complement C4 levels?
Disseminated intravascular coagulation (DIC), acute glomerulonephritis, chronic hepatitis, and SLE.
What is the function of fibrinogen?
To form fibrin clot when activated by thrombin.
Decreased levels of fibrinogen is indicative of what?
Extensive coagulation, during which fibrinogen is consumed.
What condition(s) causes an elevated C-Reactive Protein (CRP)?
Atherosclerosis (fatty deposits accumulating in the inner lining of the arteries).
hsCRP is most commonly used to detect what condition?
Cardiovascular Disease
What is the most abundant class of antibodies found in both plasma and lymph?
IgG
IgG antibodies act on what?
Bacteria, fungi, viruses, and foreign particles by agglutination, opsonization, and complement activation and by neutralizing toxins.
IgG is increased in which conditions?
Liver disease, infections, IgG myeloma, parasitic disease, and rheumatic diseases.
Decreased IgG levels are associated with what conditions?
Acquired immunodeficiency, hereditary deficiency, and non-IgG myeloma.
Where does secretory IgA remain active?
In the digestive and respiratory tracts.
In what condition(s) is serum IgA increased?
Liver disease, infections, and autoimmune diseases.
Myoglobin is the primary oxygen-carrying protein found where?
In striated skeletal muscle and cardiac muscle.
Cardiac troponins are considered the “gold standard” for diagnosis of what syndrome?
Acute Coronary Syndrome (ACS)
Fetal fibronectin (fFN) is used to help predict what?
The short-term risk of premature delivery.
Where is fFN produced?
At the boundary between the amniotic sac and the lining of the uterus.
What types of samples are unacceptable for serum total protein testing?
Hemolyzed specimens.
What total protein quantitation method measures the amount of nitrogen in the specimen?
Kjeldahl
Why is the Kjeldahl method no longer used in clinical laboratories?
It is time consuming and relies on some assumptions that are not always true.
What total protein quantitation method is most commonly used in clinical laboratories?
Biuret
What is the principle of the Biuret reaction?
Based on the principle that in an alkaline medium and the presence of at least two peptide bonds, cupric ions (Cu2+) will complex with groups involved in the peptide bond to form a violet-colored chelate.
During the Biuret reaction, at what absorbance is the colored chelate measured?
540 nm
During the Biuret reaction, the absorbance is proportional to what?
The number of peptide bonds present which reflects the total protein concentration of the specimen.
