Blood Glucose Estimation Test (M) Flashcards
True or False.
Glucose test is not routinely performed in the lab
False, because it is routinely performed in the lab
What clinical disorder can be diagnosed via glucose test?
Diabetes mellitus
What is the reference range for glucose test?
70 - 100 mg/dL
What is the unit for glucose test?
mg/dL
What are the sxs that can be used for glucose test?
1) Fasting venous plasma
2) Random Blood Sugar (RBS)
3) CSF
4) Synovial fluid
5) Serous fluid
6) Urine
What is the required time of fasting for fasting venous plasma sx?
8 - 10 hrs
What happens if the sx is unrefrigerated (there is a delay in testing)?
Decreases 7 mg/dL per hr
What happens if the sx is refrigerated (test can’t be done promptly)?
Decreases 2 mg/dL per hr
What is the result if whole blood is used as sx for glucose testing?
10 - 15% lower
The results if whole blood is used for glucose testing is lower than what?
Than serum and plasma
What is the percentage of the plasma concentrations of CSF?
60 - 70%
How to prevent the loss of glucose (in glucose test)?
Plasma glucose should be separated within an hour
What etubes should be used if glucose testing will be delayed?
Red, yellow, and gray tops
True or False.
Venous blood glucose is higher than capillary blood (RBS)
False, because venous blood glucose is lower than capillary blood (RBS)
How high or how low is venous blood glucose compared to capillary blood (RBS)?
It is lower than 7 mg/dL compared to capillary blood (RBS)
What tube is preferred to be used for glucose test?
Gray top
Why is gray top preferred to be used for glucose test?
Because it contains potassium oxalate / sodium fluoride
What is the action of enolase?
It inhibits glycolytic enzyme
2 mg of NaF per mL of blood prevents what?
It prevents glycolysis up to 48 hrs
What is the action of fluoride (sodium fluoride)?
It binds w/ magnesium w/c causes inhibition of enzyme enolase
What are the 2 types of methods of glucose estimation test?
1) Chemical method
2) Enzymatic method
What are the different methods under chemical method of glucose estimation test?
1) Oxidation - reduction
2) Hagedorn Jensen
3) Condensation method
What are the different methods under oxidation - reduction of glucose estimation test?
1) Folin-Wu
2) Nelson-Somogyi
3) Neocuprione (Neocupreine) method
4) Benedict’s method
What is the principle of oxidation - reduction?
The ability of glucose to directly reduce cupric ions to monovalent cuprous ions in the presence of heat
What are the chemical formulas for oxidation - reduction?
Heat: CuSo4 (cupric sulfide) + reducing substance -> Alkali: Cu2O (cuprous oxide) + oxidized substance -> color (blue / green to orange / red)
*heat and alkali rxns
What are the principles of Folin-Wu?
1) It uses tungstic acid to remove protein from serum
2) Measures sugar (FBS)
What are the principles of Nelson-Somogyi?
1) It uses zinc hydroxide
2) It measures true glucose (FBG)
What is the color of positive result of Neocuprione’s (Neocupreine’s) method?
(+) : yellow
What sx (and its volume) is used for Benedict’s test?
1 mL urine
What is the component of Benedict’s rgnt?
Copper sulfate
What is the chemical formula (or equation) of Folin-Wu?
Cu^+ + Phosphomolybdate acid -> phosphomolybdenum (blue)
What is the chemical formula (or equation) of Nelson-Somogyi?
Cu^+ + Arsenomolybdate acid -> arsenomolybdenum (blue)
What is the chemical formula (or equation) of Neocupreine method?
Cu^+ + neocuprine -> yellow to yellow-orange complex
What is the chemical formula (or equation) of Benedict’s method?
Copper sulfate (blue) + glucose + heat -> green -> yellow -> orange -> brick red
*color reactions depends on the intensity of the rxn
What is the principle of Hagedorn Jensen?
Potassium ferricyanide is reduced to potassium ferrocyanide when heated w/ alkaline solution by a reducing sugar / substance
What is the chemical formula (or equation) of Hagedorn Jensen?
Potassium ferricyanide -> via the action of reducing substance -> potassium ferrocyanide
What is the method under condensation method?
Ortho-toluidine, Dubowski
What is the principle of Ortho-toluidine, Dubowski?
Glucose + O-toluidine in glacial acetic acid = N-glucosylamine (Blue-green color)
What is the chemical formula (or equation) of Ortho-toluidine, Dubowski?
Glucose + O-toluidine -> via the action of HAc along w/ boiling (100 DC) -> Bluish-green complex (Glycosylamine)
What is the meaning of GOD?
Glucose Oxidase
What is the action of glucose oxidase?
It is an enzyme that catalyzes the oxidation of glucose to gluconic acid and hydrogen peroxide
What are the characteristics of glucose oxidase?
1) It is very specific
2) It reacts only w/ beta-glucose
What is the principle (or chemical formula / equation) of glucose oxidase?
Glucose + O2 -> via the action of GOD -> Gluconic acid + H2O2
H2O2 + 4-NH3-Antipyrine -> via the action of POD -> Quinonimine + H2O
What are the different enzymatic methods?
1) Glucose oxidase
2) Hexokinase
What is the reference method (enzymatic method)?
Hexokinase
What is the principle of hexokinase?
Glucose-6-phosphate formed from glucose and ATP by hexokinase (HK) is oxidized by NAD in a rxn catalyzed by glucose-6-phosphate dehydrogenase (G6PD) to give NADPH, w/c is quantitated spectrophotometrically at 340 nm
Where does G6P came from?
From glucose and ATP by HK
What is quantitated spectrophotometrically?
NADPH
NADPH is quantitated spectrophotometrically at how many nm?
340 nm
What is the principle (chemical formula or equation) of hexokinase?
glucose -> via the action of HK ; ATP becomes ADP -> G6P -> via the action of HK ; NAD becomes NADH -> 6-phosphogluconate
Is NADH same w/ NADPH?
Yes
Answer the ff questions:
Given test: Hemoglobin A1C (%)
What are the diagnosis (interpretations) for the ff results (values):
1) < or equal to 5.6
2) 5.7 - 6.4
3) > or equal to 6.5
1) Normal
2) High risk / prediabetes
3) Diabetes
What is the unit for HBA1C test?
%
What should be done if the result for HBA1C test is > or equal to 6.5?
It is confirmed by repeat testing in absence of unequivocal hyperglycemia
When is FPG measured?
After 8 - hr fast
Answer the ff questions:
Given test: FPG (mg/dL)
What are the diagnosis (interpretations) for the ff results (values):
1) < or equal to 99
2) 100 - 125
3) > or equal to 126
1) Normal
2) Impaired fasting glucose
3) Diabetes
What should be done if the result for FPG is > or equal to 126?
It should be confirmed by repeat testing in absence of unequivocal hyperglycemia
What is the unit for FPG?
mg/dL
Answer the ff questions:
Given test: PPG (mg/dL)
What are the diagnosis (interpretations) for the ff results (values):
1) < or equal to 139
2) 140 - 199
3) > or equal to 200
1) Normal
2) Impaired glucose tolerance
3) Diabetes
What should be done if the result for PPG is > or equal to 200?
It should be confirmed by repeat testing in absence of unequivocal hyperglycemia
What is the unit for PPG?
mg/dL
When and how is PPG measured?
It is measured w/ an OGTT performed 2 hrs after 75 g oral glucose load
Answer the ff questions:
Given test: Random plasma glucose (mg/dL)
What are the diagnosis (interpretations) for the ff results (values):
1) < or equal to 200
1) Diabetes
What is the unit of random plasma glucose?
mg/dL
What are associated w/ random plasma glucose?
1) Polyurea
2) Polydipsia
3) Polyphagia
What are the 3 tubes that are used (in reality) for glucose oxidase?
1) GLU + Blank
2) GLU + Standard
3) GLU + Unknown
What should be putted for the label of 3 tubes (used in glucose oxidase)?
1) Blank
2) Standard
3) Unknown
*can be shorten or short distinct labels can be used
What is the process (or steps) for glucose oxidase?
1) Label test tubes
2) Transfer 1500 uL GLUCOSE working rgnt to each tube and place in a 37 DC H2O bath
3) Add 1 uL sx to each tubes
4) Gently mix the tubes
5) Incubate for 10 mins
6) Spectrophotometer: read and record A using 500 nm
7) Semi-automated chemistry analyzer: feed on the machine
How many uL of glucose working rgnt is used?
1500 uL
What is the temp of H2O bath?
37 DC
What is the volume of the sx added to each tubes?
1 uL
What is the time duration of incubation?
10 mins
Using the spectrophotometer, at what nm should the A be read and recorded?
500 nm
What is the reference range (of glucose oxidase?)?
70 - 100 mg/dL
How many hours of fasting is required for fasting blood sugar?
8 - 10 hrs fasting
When is RBS collected?
Anytime regardless of the meal
When is 2 hr Postprandial Blood Sugar collected?
2 hrs after eating
What are the principles (working principle) of HBA1C test?
1) It is a blood test that provides your average lvls of blood glucose over the past 2 - 3 mos (lifespan of RBCs)
2) No fasting required
What is the lifespan of RBCs?
2 - 3 mos
What is the meaning of FGSP?
Fructosamine Glycated Serum Protein
What is the principle (working principle) of OGTT?
It measures blood glucose after you fast for at least 8 hrs
What is the meaning of OGTT?
Oral Glucose Tolerance Test
What is the result (normal?) of OGTT for nonpregnant pts?
75 g
What is the result (normal?) of OGTT for pregnant pts?
100 g
What is the result (normal?) of OGTT for children (not exceeding 75 g)?
0.75 g/kg of body weight