glycosylated hgb nycocard Flashcards
most abundant type of hemoglobin in human adults, making up 97% of total hemoglobin
Hemoglobin A
components of Hemoglobin A
2 α-chains and 2 β-chains.
types of glycated hemoglobins found in hemoglobin A1
A1a, A1b, A1c
T/F Glycated hemoglobins migrate more rapidly than Hemoglobin A in an electric field.
T
Glycosylated hemoglobin is formed in the body by the _____ of a sugar residue to the amino group of hemoglobin.
non-enzymatic addition
Red blood cells with glucose attached, formed when glucose reacts with hemoglobin.
HbA1c
T/F: The formation of glycosylated hemoglobin is irreversible and reflects blood glucose levels over the past 2 to 3 months.
T
what percent of hemoglobin in the body is made up of Hemoglobin A2 and Hemoglobin F
Hemoglobin A2: 2.5%
Hemoglobin F: 0.5%
rate of formation of glycosylated hemoglobin is directly proportional to ___
concentration of plasma glucose in the blood.
The glucose molecule attaches non-enzymatically to hemoglobin, forming a ___ through a ___ base and then an ____ rearrangement to form HbA1c
ketoamine, Schiff, Amadori
HbA1c provides a time-averaged picture of the patient’s blood glucose concentration over the past ___ months
2-3
T/F: HbA1c is more reliable for long-term diabetes control monitoring than random plasma glucose.
T
Odd One Out: Formation of HbA1c
A) Glucose condensation
B) Schiff base formation
C) Enzymatic reaction
D) Amadori rearrangement
C) Enzymatic reaction – formation of HbA1c is non-enzymatic.
major fraction of glycated hemoglobin and its proportion of total HbA1
HbA1c - 80% of HbA1.
T/F Glycation may also occur at other sites on the hemoglobin molecule, such as lysine residues or on the alpha chains.
T
How is total glycated hemoglobin measured in lab
boronate affinity chromatography
decreased red blood cell lifespan results in ___ glycosylated hemoglobin levels because the hemoglobin has less time to become glycosylated.
decreased
T/F The rate of formation of glycosylated hemoglobin is directly proportional to the concentration of glucose in the blood.
T
How often does the ADA recommend HbA1c testing for patients who are meeting treatment goals and have stable glycemic control
2x a yr
How often should HbA1c be tested for patients who are not meeting glycemic goals or whose therapy has changed?
quarterly
target HbA1c level recommended for non-pregnant adults to reduce the risk of complications
<7%
Which of the following complications is NOT reduced by lowering HbA1c to less than 7%?
A) Microvascular complications
B) Retinopathy
C) Hypoglycemia
D) Neuropathy
C) Hypoglycemia – Hypoglycemia is not a complication reduced by lowering HbA1c
goal HbA1c level goal for selected individual patient without significant hypoglycemia
lowering HbA1c to <6%
what amino acid is glucose’s favorite landing site
N-terminal Valine
glycated hemoglobin measurement method uses polyclonal or monoclonal antibodies targeted toward the glycated N-terminal group of the β-chain of hemoglobin
Immunoassays
separates based on chemical structure using borate to bind glycosylated proteins.
Affinity Chromatography
Odd One Out: Based on structural differences
A) Immunoassays
B) Affinity Chromatography
C) Electrophoresis
D) None of the above
C) Electrophoresis – based on charge differences.
type of chromatography separates glycated hemoglobin based on charge differences using a positive-charge resin bed
Ion-exchange chromatography
method of glycated hemoglobin measurement that is temperature dependent and affected by hemoglobinopathies
Ion-exchange chromatography
T/F: Electrophoresis separates hemoglobin based on charge differences and can be affected when Hemoglobin F values are greater than 7%.
T
gold standard for identifying glycated hemoglobin
High-pressure liquid chromatography (HPLC)
T/F: Isoelectric focusing is a form of electrophoresis that uses the isoelectric point to separate glycated hemoglobin.
T
Odd One Out: Charge differences
A) High-pressure liquid chromatography (HPLC)
B) Isoelectric focusing
C) Affinity chromatography
D) Ion-exchange chromatography
C) Affinity chromatography – separates based on chemical structure
type of sample required for HbA1c testing
EDTA whole blood
T/F Patients need to be in a fasting state for HbA1c testing.
F – do not need to fast
How long can whole blood samples for HbA1c testing be stored at 4°C?
1 wk