UNIT 4 - Laboratory Methods (Carbohydrates)

Question 1

What is the most commonly used specimen for glucose testing?

Answer 1

Serum or plasma

Question 2

What specimens can be considered for glucose testing

Answer 2

Whole blood,
plasma,
serum,
cerebrospinal fluid,
pleural fluid, and
urine

Question 3

What is the standard clinical specimen for glucose testing, and which additive is commonly used?

Answer 3

Venous plasma with sodium fluoride as an additive.

Question 4

What color is the stopper of the tubes containing sodium fluoride for glucose testing?

Answer 4

Gray

Question 5

What type of blood is used in Point-of-Care Testing (POCT) for glucose levels?

Answer 5

Capillary blood.

Question 6

By how much is the glucose concentration in whole blood lower than in plasma?

Answer 6

10% - 15% lower.

Question 7

At what rate is glucose metabolized at room temperature in a blood sample?

Answer 7

7 mg/dL/hour (0.4 mmol/L/hour).

Question 8

How much does glucose decrease per hour when a blood sample is stored at 4°C?

Answer 8

2 mg/dL/hour (0.1 mmol/L/hour).

Question 9

What is the conversion factor for glucose from mg/dL to mmol/L?

Answer 9

0.0555.

Question 10

How long should a serum specimen be separated from the cells to avoid glycolysis according to Henry’s 21st edition?

Answer 10

30 minutes.

Question 11

How long does sodium fluoride prevent glycolysis in whole blood when refrigerated?

Answer 11

Up to 48 hours.

Question 12

What is the recommended fasting period for obtaining a fasting blood glucose (FBG) sample?

Answer 12

8 to 10 hours (not longer than 16 hours).

Question 13

When is fasting plasma glucose (FPG) typically higher, morning or afternoon?

Answer 13

FPG is higher in the morning.

Question 14

It uses a strip; after capillary puncture, blood flows into the filter paper impregnated with reagent. The strip is then inserted into the glucometer, and the result appears after a few minutes.

Answer 14

glucometer

Question 15

What can be added to a sample if it is not separated from the cells within 30 minutes?

Answer 15

Sodium fluoride.

Question 16

How long should a serum specimen be separated from cells according to Bishop?

Answer 16

1 hour.

Question 17

How long can sodium fluoride prevent glycolysis in whole blood when refrigerated?

Answer 17

Up to 48 hours.

Question 18

What is the screening test for diabetes mellitus that is taken after at least 8 hours of fasting?

Answer 18

Fasting Blood Sugar (FBS) or Fasting Blood Glucose.

Question 19

It indicates a prediabetic state and increased risk of developing diabetes, but it is not a clinical entity.

Answer 19

impaired fasting glucose

Question 20

What type of test uses whole blood in EDTA and provides a picture of a patient’s blood glucose levels over the past three months?

Answer 20

Hemoglobin A1c (HbA1c).

Question 21

What is the reference range for a normal Hemoglobin A1c (HbA1c) level?

Answer 21

4% - 6% (Henry’s 21st edition).

Question 22

What HbA1c range indicates an increased risk for diabetes?

Answer 22

5.7% - 6.4%

Question 23

At what HbA1c level is diabetes diagnosed?

Answer 23

≥ 6.5%.

Question 24

What test is also known as glycosylated albumin or glycated albumin and monitors glucose control over the previous 3-6 weeks?

Answer 24

Fructosamine test.

Question 25

What is the reference value for the Fructosamine test?

Answer 25

205 - 285 µmol/L.

Question 26

What type of glucose test is randomly collected?

Answer 26

Random Blood Sugar (RBS).

Question 27

In the 2-Hour Post Prandial Blood Sugar (PPBS) test, how much glucose is administered, and when is the sample drawn?

Answer 27

75g of glucose is administered, and the sample is drawn 2 hours after consumption of food

Question 28

What are the two types of Glucose Tolerance Tests (GTT)?

Answer 28

Oral Glucose Tolerance Test (OGTT) and Intravenous Glucose Tolerance Test (IVGTT).

Question 29

What type of GTT is performed for patients with malabsorption syndrome who cannot consume the glucose load?

Answer 29

Intravenous Glucose Tolerance Test (IVGTT).

Question 30

How should a patient prepare for an Oral Glucose Tolerance Test (OGTT)?

Answer 30

The patient should consume 150g of carbohydrates per day for 3 days, discontinue medications affecting glucose tolerance, fast for 8-10 hours, and avoid excessive physical activity.

Question 31

At what fasting blood glucose (FBG) level should an OGTT be terminated before giving the glucose load?

Answer 31

If FBG is greater than 140 mg/dL.

Question 32

What is the glucose load for an adult in an OGTT?

Answer 32

75g of glucose dissolved in 300 mL of water.

Question 33

What glucose dose is given to children in an OGTT?

Answer 33

1.75g of glucose per kilogram of body weight, up to a maximum of 75g.

Question 34

What is the specimen required for the Hemoglobin A1c (HbA1c) test?

Answer 34

Whole blood in EDTA.

Question 35

How does Hemoglobin A1c (HbA1c) relate to long-term glucose control?

Answer 35

It monitors long-term diabetes control over the previous 2-3 months.

Question 36

For every 1% increase in HbA1c, how much does plasma glucose change?

Answer 36

A 1% increase in HbA1c corresponds to a 35 mg/dL (2 mmol/L) change in plasma glucose.

Question 37

What is the union or reaction involved in Hemoglobin A1c formation?

Answer 37

HbA1c is formed from the reaction between glucose and the hemoglobin protein, specifically the beta chain of hemoglobin.

Question 38

What is the reference value for Fructosamine?

Answer 38

205-285 µmol/L.

Question 39

What is the glucose specimen of choice for measuring glucose levels, and what additive is used?

Answer 39

Venous plasma is the standard clinical specimen, with sodium fluoride as the additive (gray stopper tubes).

Question 40

What is the glucose concentration difference between whole blood and plasma?

Answer 40

Glucose concentration in whole blood is 10%-15% lower than in plasma.

Question 41

What are the three types of ketones produced by the liver?

Answer 41

Acetone, 2% acetoacetic acid, 20% 3-β-hydroxybutyric acid 78%

Question 42

What conditions can lead to increased ketone levels in the body?

Answer 42

Diabetes mellitus, starvation/fasting, high-fat diets, prolonged vomiting, glycogen storage disease

Question 43

What specimen types are used to detect ketones?

Answer 43

Fresh serum or urine

Question 44

hat is the accumulation of ketones in the blood called?

Answer 44

Ketonemia

Question 45

What is the accumulation of ketones in urine called?

Answer 45

Ketonuria

Question 46

Which test uses ferric chloride to detect acetoacetic acid and produces a red color?

Answer 46

Gerhardt’s test

Question 47

Which test uses sodium nitroprusside to detect acetoacetic acid and produces a purple color?

Answer 47

Sodium nitroprusside test

Question 48

Which enzymatic test detects 3-β-hydroxybutyric acid or acetoacetic acid?

Answer 48

3-hydroxybutyrate dehydrogenase test

Question 49

What is defined as persistent albuminuria in two out of three urine collections, with values between 30-300 mg/24h?

Answer 49

Microalbuminuria

Question 50

What ratio establishes clinical proteinuria or macroalbuminuria?

Answer 50

Albumin–creatinine ratio ≥ 300 mg/24 h or ≥ 300 μg/mg creatinine

Question 51

What collection methods are used for microalbuminuria testing?

Answer 51

Random spot collection, 24-hour collection, timed 4-hour overnight collection

Question 52

What is the normal fasting plasma glucose (FPG) range in mg/dL?

Answer 52

70-99 mg/dL

Question 53

What is the normal fasting plasma glucose (FPG) range in mmol/L?

Answer 53

3.9-5.5 mmol/L

Question 54

What is the impaired fasting glucose (FPG) range in mg/dL?

Answer 54

100-125 mg/dL

Question 55

What is the impaired fasting glucose (FPG) range in mmol/L?

Answer 55

5.6-6.9 mmol/L

Question 56

What FPG level in mg/dL indicates a provisional diabetes diagnosis?

Answer 56

≥ 126 mg/dL

Question 57

What FPG level in mmol/L indicates a provisional diabetes diagnosis?

Answer 57

≥ 7.0 mmol/L

Question 58

What is the normal two-hour plasma glucose (PG) range in mg/dL?

Answer 58

Answer: ≤ 140 mg/dL

Question 59

What is the normal two-hour plasma glucose (PG) range in mmol/L?

Answer 59

≤ 7.8 mmol/L

Question 60

What is the impaired glucose tolerance (IGT) range in mg/dL for a two-hour plasma glucose test?

Answer 60

140-199 mg/dL

Question 61

What is the impaired glucose tolerance (IGT) range in mmol/L for a two-hour plasma glucose test?

Answer 61

7.8-11.1 mmol/L

Question 62

What two-hour PG level in mg/dL indicates a provisional diabetes diagnosis?

Answer 62

≥ 200 mg/dL

Question 63

What two-hour PG level in mmol/L indicates a provisional diabetes diagnosis?

Answer 63

≥ 11.1 mmol/L

Question 64

methods for glucose determinatio

Answer 64

chemical -oxidation reduction -condensation enzymatic -glucose dehydrogenase -glucose oxidase -hexokinase method

Question 65

OXIDATION REDUCTION METHODS

Answer 65

Alkaline Copper Reduction Method Alkaline Ferric Reduction Method (Hagedorn Jensen)

Question 66

Alkaline Copper Reduction Methods

Answer 66

Folin Wu Method Nelson Somogyi Method Neocuprein Method Benedict’s Method (Modification of FolinWu)

Question 67

Alkaline Copper Reduction Method Principle

Answer 67

Reduction of cupric ions to cuprous ions forming cuprous oxide in hot alkaline solution by glucose.

Question 68

In the Folin Wu method, what does cuprous oxide react with to produce phosphomolybdenum blue?

Answer 68

Phosphomolybdate

Question 69

What does cuprous oxide react with in the Nelson-Somogyi method to form arsenomolybdenum blue?

Answer 69

Arsenomolybdate

Question 70

What reagent is used in the Neocuprein Method to detect glucose, and what color complex is produced?

Answer 70

2,9-Dimethyl-1,10-Phenantroline Hydrochloride; yellow or yellow-orange complex

Question 71

What is the purpose of Benedict’s Method, and what stabilizing agent does it use?

Answer 71

Detection and quantitation of reducing substances in body fluids; citrate or tartrate as a stabilizing agent

Question 72

What does copper sulfate react with in Benedict's Method, and what precipitate is formed?

Answer 72

Glucose under heat; brick red precipitate

Question 73

What is reduced in the Alkaline Ferric Reduction Method (Hagedorn Jensen) for glucose measurement?

Answer 73

Ferricyanide is reduced to ferrocyanide.

Question 74

What type of colorimetry is used in the Hagedorn Jensen method, and what is the nature of the end product?

Answer 74

Inverse colorimetry; the end product is colorless.

Question 75

What is the name of the condensation method used for glucose measurement?

Answer 75

Ortho-toluidine (Dubowski Method)

Question 76

What is the end product of the Ortho-toluidine (Dubowski Method)?

Answer 76

Green-colored end product

Question 77

How do we produce the green colored end product in ortho toluidine

Answer 77

Glucose + Aromatic amines (with Glacial Hac and Heat) ---> Glycosylamine + Schiff's base

Question 78

What enzymes are involved in the Glucose Dehydrogenase method?

Answer 78

Mutarotase, Glucose Dehydrogenase, Diaphorase

Question 79

What does Mutarotase do in the Glucose Dehydrogenase method?

Answer 79

Converts α-D-glucose to β-D-glucose

Question 80

What reaction does Glucose Dehydrogenase catalyze in the Glucose Dehydrogenase method?

Answer 80

Converts β-D-glucose + NAD to D-gluconolactone + NADH

Question 81

What is the role of Diaphorase in the Glucose Dehydrogenase method?

Answer 81

Converts MTT + NADH to MTTH (blue color) + NAD

Question 82

What is the significance of NADH in the Glucose Dehydrogenase method?

Answer 82

NADH produced is proportional to glucose concentration

Question 83

Which method for glucose measurement can result in falsely decreased values due to uric acid, bilirubin, and ascorbic acid?

Answer 83

Glucose Oxidase method

Question 84

What substance can cause falsely increased glucose values in the Glucose Oxidase method?

Answer 84

Bleach

Question 85

Which chromogens are used in the Colorimetric Glucose Oxidase (Saifer-Gernstenfield) method?

Answer 85

3-methyl-2-benzothiazolinone hydrazone and N,N-dimethylaniline

Question 86

What does the Polarographic Glucose Oxidase method measure?

Answer 86

The rate of oxygen consumption proportional to glucose concentration

Question 87

Which glucose measurement method is considered the most specific?

Answer 87

Hexokinase method

Question 88

What wavelength is used to measure NADPH in the Hexokinase method?

Answer 88

340 nm