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Clinical Chemistry > CARBOHYDRATES LAB > Flashcards

CARBOHYDRATES LAB Flashcards

1
Q

Specimens for carbohydrate analysis:

A

Whole blood, plasma, serum, urine, CSF, synovial, serious fluid

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2
Q

standard clinical specimen

A

fasting venous plasma

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3
Q

T or F: Serum is appropriate for glucose analysis if it is separated from the cells immediately after centrifugation
(approximately 60 minutes after blood collection)

A

F; approximately 30 mins

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4
Q

Bacteria, WBC, RBCs might consume the glucose present in the sample which can ____ the glucose results

A

lower

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5
Q

What should be used if processing will be delayed for more than 30 minutes?

A

sodium fluoride

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6
Q

Mechanism of action of fluoride in preventing glycolysis

A

Fluoride binds to magnesium, inhibiting enolase which is necessary for glycolysis

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7
Q

If whole blood is refrigerated, ______/mL of whole blood prevents glycolysis for up to ____hours

A

2 mg of NaF; 48

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8
Q

Fasting blood sugar should be obtained after ____ of fasting (but not >16hrs)

A

8-10 hours

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9
Q

CSF glucose concentration is approximately ______that of plasma concentrations.

A

60%-70%

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10
Q

How many hours should blood glucose be obtained before spinal tap?

A

1-2 hours

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11
Q

T or F: Peritoneal fluid glucose is the same as plasma glucose

A

T

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12
Q

Whole blood gives approximately ____LOWER glucose levels than serum or plasma.

A

10-15%

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13
Q

Venous blood glucose is 7mg/dL ____ than capillary blood glucose due to tissue metabolism

A

lower

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14
Q

T or F: Capillary blood glucose is not the same with arterial blood glucose

A

F; it is the same

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15
Q

Rate of glucose metabolism at RT

A

7 mg/dl/hr

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16
Q

At ___, glucose decreases by approximately 2mg/dl/hr.*

A

4 deg. Celsius

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17
Q

T of F: The rate of metabolism is lower with bacterial contamination or leukocytosis.

A

False; higher

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18
Q

In serum specimens without bacterial contamination or leukocytosis, results are clinically acceptable up to ______

A

90 minutes before separation of serum from cells.

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19
Q

Glucose methodologies can be categorized into:

A

Chemical and Enzymatic methods

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20
Q

Methodologies under Chemical method

A

Copper reduction, Ferric reduction, condensation method

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21
Q

Principle of copper reduction method

A

glucose and other reducing sugars convert cupric to cuprous ions in the presence of heat and alkali

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22
Q

Why is Folin Wu method sensitive but NOT SPECIFIC?

A

Because non-glucose reducing substances also react with the test

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23
Q

End color of Folin Wu

A

Phosphomolybdenum BLUE

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24
Q

Why is Nelson Somogyi method BOTH sensitive and specific

A

Because after PFF preparation, non- glucose reducing substances are adsorbed by BARIUM SULFATE

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25
Q

end color of Nelson Somogyi method

A

Arsenomolybdenum BLUE

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26
Q

end color of neocuproine method

A

Cuprous-Neocuproine Complex (YELLOW or YELLOW-ORANGE)

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27
Q

Which method is a modification of the Folin Wu?

A

Benedict’s method

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28
Q

stabilizing agents used in Benedict’s

A

citrate and tartrate

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29
Q

Positive and negative result for Benedict’s

A

(+) Green - yellow - brick red ppt

(-) blue

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30
Q

It is the modern version of Benedict’s method

A

Clinitest tablet

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31
Q

What sample is used in clinitest tablet

A

Urine

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32
Q

Phenomenon that occurs in clinitest tablet test when there is increased glucose level

A

PASS THROUGH PHENOMENON

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33
Q

Other term for Ferric Reduction method

A

Hagedorn jensen method

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34
Q

Principle of ferric reduction method

A

Inverse Colorimetry (reduction of yellow ferricyanide to colorless ferrocyanide)

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35
Q

Disappearance of color is measured at which wavelength

A

400 nm

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36
Q

Which method is employed in autoanalyzers

A

Ferric reduction method

37
Q

Principle of condensation method

A

The aldehyde group of glucose condenses with aromatic amines in hot acetic acid solution to form colored derivatives

38
Q

It is the most specific non-enzymatic method for glucose measurement

A

Orthotoluidine method / Dubowski method

39
Q

disadavantage of Dubowski method

A

carcinogenic and teratogenic

40
Q

end color of Dubowski method and at which wavelength is it measured

A

bluish green; 620-630 nm

41
Q

3 enzyme systems commonly used to measure glucose

A

glucose dehydrogenase, glucose oxidase, and hexokinase

42
Q

Percentage of alpha and beta glucose

A

Alpha - 35%

Beta - 65%

43
Q

Enzyme involved in conversion of alpha to beta glucose

A

mutarotase

44
Q

principle of glucose dehydrogenase method

A

amount of reduced nicotinamide adenine dinucleotide is proportional to glucose concentration in the sample

45
Q

end color of glucose dehydrogenase method

A

blue

46
Q

Why is glucose oxidase method the most specific enzymatic method?

A

It reacts only with Beta-d-glucose

47
Q

The coupled reaction involved in glucose oxidase method is known as ___

A

TRINDER’S REACTION

48
Q

Reducing agents causing falsely decreased results (13)

Oxidizing agents causing falsely increased results (2)

A

Reducing agents: uric acid, ascorbic acid, bilirubin, glutathione, creatinine, formalin, hemoglobin, tetracycline, l-cysteine, l-dopa, dopamine, methyldopa, and citric acid
Oxidizing agents: bleach and detergents

49
Q

In polarographic method, ____ is measured and is proportional to the amount of glucose present

A

oxygen depletion

50
Q

H2O2 is prevented from re-forming O2 by adding:

A

molybdate, iodide, catalase and ethanol

51
Q

Why glucose oxidase is NOT the reference method?

A

Glucose oxidase is very specific, it only measures beta-glucose
Glucose oxidase is affected by reducing and oxidizing agents

52
Q

REFERENCE METHOD/ GOLD STANDARD TEST

A

hexokinase method

53
Q

principle of hexokinase method

A

glucose concentration is proportional to the rate of production of nicotinamide adenine dinucleotide phosphate (NADPH)

54
Q

Wavelength used for hexokinase method

A

340 nm

55
Q

hexokinase method can be performed on serum or plasma collected using

A

heparin, EDTA, fluoride, oxalate, or citrate

56
Q

Is hexokinase method, specific or non specific?

A

It is non specific because any sugar with 6 carbon units will react with the test (fructose, glucose, galactose)

57
Q

Analogy:
RBG: _____
_____: Screening

A

Monitoring; FBG

58
Q

RBG is requested during:

A

Insulin Shock

Hyperglycemic Ketonic Coma

EMERGENCY CASES 

59
Q

There is a fast increase in the glucose level approxmately how many minutes after a meal?

A

30 minutes

60
Q

blood glucose level normalizes within ___

A

2 hrs

61
Q

In 2 hr PPBG, how many grams of glucose should be administered, and when should the sample be drawn?

A

75 g of glucose, after 2 hours

62
Q

also referred to as CHALLENGE test

A

GTT

63
Q

Procedure for Janney Isaacson method

A

Procedure:

 Fasting blood and urine samples are obtained

 Glucose load is given

 Blood and urine samples are collected for glucose measurements 30 minutes, 1 hour, 2 hours and 3 hours after

64
Q

Procedure for Exton Rose method

A

Procedure:

 Fasting blood and urine samples are obtained

 Glucose load is given

 Blood and urine samples are collected for glucose measurements 30 minutes, 1 hour, 2 hours and 3 hours after

65
Q

how many grams of glucose in ___ mL of water is used in double dose method?

A

100 g; 650 mL

66
Q

Expected added plasma glucose after:

30 mins, 1 hr, 2hr, and 3 hr

A

30 mins: 30-60 mg/dL above fasting
1 hr: 20-50 mg/dL above fasting
2 hr: 5-15 mg/dL above fasting
3 hr: fasting level or below

67
Q

Requirements for OGTT

A
  1. Patient should be ambulatory (mobile)
  2. The test should be performed after an overnight 8 to14-hour fasting (not longer than 16 hours)
  3. Unrestricted diet of 150 g of CHO per day for 3 days prior to testing
  4. Individual should not eat food, drink tea, coffee, or alcohol, or smoke cigarettes during the test, and should be seated.
68
Q

Glucose load for:

Adults, pregnant women (suspected of GDM), and for children

A

Adults: 75 g
Preg: 100 g
Children: 1.75 g/kg of body weight

69
Q

which GTT is used for diabetics with GIT d/o

A

IVGTT

70
Q

glucose load for IVGTT, and time of glucose load administration and sample collection

A

0.5 g/kg of body weight; within 3 minutes; 5 mins after glucose administraiton

71
Q

Indications for the use of IVGTT:

A

Unable to tolerate large carbohydrate in the diet

🞑 Presence of altered gastric physiology

🞑 Previous operation or surgery of the gastrointestinal tract

🞑 Presence of chronic malabsorption syndrome

72
Q

INTERPRETATION OF RESULTS FOR FASTING BLOOD GLUCOSE

A

Non Diabetic: < 100mg/dL

Impaired FBS: > 100mg/dl but < 126 mg/dL

Diabetes Mellitus: > 126 mg/dL

73
Q

INTERPRETATION OF RESULTS FOR ORAL GLUCOSE TOLERANCE TEST

A

Normal OGTT (2hr Glucose): < 140 mg/dL

Impaired OGTT (2hr Glucose): 140-199 mg/dL
Diabetes Mellitus (2hr Glucose): > 200 mg/dL
74
Q

DIAGNOSTIC CRITERIA FOR DIABETES MELLITUS

A

RBG: > 200 mg/dL with symptoms of DM
FBG: > 126 mg/dL
2-hr Post Prandial: > 200 mg/dL
HbA1c : > 6.5%

75
Q

T: F glycosylated Hgb is more reliable than RBG for monitoring SHORT TERM glucose control

A

F; long term

76
Q

SOC for glycated hemoglobin

A

non fasting whole blood drawn in EDTA

77
Q

reference range for HbA1c

A

4-6%

78
Q

T of F: for every 1% change in HbA1c value, 35 mg/dl is added to plasma glucose level

A

T

79
Q

Any condition associated with shorted red blood cell survival will ____ the HbA1c level as the result of ____

A

Lower; reduced exposure to plasma glucose

80
Q

Conditions associated with low HbA1c level due to shortened RBC survival

A

Hemolysis

Recovery from acute blood loss

Transfusions

Splenectomy

81
Q

most widely used to assess short-term glycemic control

A

fructosamine (glycated albumin)

82
Q

time interval for glycated hemoglobin and fructosamine

A

2-3 months; 3-6 weeks

83
Q

When should fructosamine not be performed?

A

When the serum albumin level is low (<3.0 mg/dL)

84
Q

specimen for POCT

A

whole blood capillary glucose

85
Q

how does hematocrit affect POCT glucose measurements

A

High Hct = lower glucose

86
Q

Procedure for One Step Method for GDM

A
  1. Collect fasting plasma (8 hours)
  2. Give 75 g glucose load
  3. Collect plasma after 1 and 2 hours
87
Q

Criteria for diagnosis of GDM using One - Step method

A

Fasting: >- to 92 mg/dL
1 hr: >- to 180 mg/dL
2 hr: >- to 153 mg/dL

88
Q

Procedure for Two Step method for GDM

A 
Step 1: 
1. Give 50 g of glucose to non fasting patient 
2. Collect plasma after 1 hr 
3. If plasma glucose level is >140 mg/dl, proceed to Step 2, if not stop 
Step 2 : 
1. Collect fasting plasma (8hrs)
2. give 100 g of glucose load 
3. Collect plasma after 1,2, and 3 hours
89
Q

Criteria for diagnosis of GDM using Two Step

A 
Accdg to Carpenter: 
Fasting: >- 95 mg/dL 
1 hr: 180 mg/dL 
2 hr: 155 mg/dL 
3 hr: 140 mg/dL 
Accdg to NDDG: 
Fasting: >- 105 mg/dL 
1 hr: >190 mg/dL 
2 hr: >-165 mg/dL 
3 hr: >-145 mg/dL

Clinical Chemistry (4 decks)

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