glucose methodologies Flashcards by CHARLENE SAN JOSE

in a normal hematocrit, whole blood glucose level is ___ % lower than the plasma glucose

10-12%

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Plasma glucose is __% lower than Serum glucose

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Capillary blood glucose: ___ higher than venous blood

2-5 mg/dL

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possible samples we can use to check for glucose level

Serum, CSF, Whole Blood, Synovial Fluid, Urine

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Standard specimen

Fasting Venous Sample

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csf sample has how many percent of glucose

60%

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Uncentrifuged coagulated blood
-can lower the glucose level for how many percent in 1 hr?

↓5-7% in 1 hour

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Prolonged standing:___ lower
without refrigerator

7 mg/dL per hour (RT)

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if the sample is refrigerated in 4*C, the glucose level will only lower down for ___ every hhr

1-2 mg/dl

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Separated nonhemolyzed sterile serum
can last in 25*C for how many hrs?

8 hrs

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Separated nonhemolyzed sterile serum
can last in 4*C for how many hrs?

72 hrs

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serum should be separated from the clot within ___

.5 to 1 hr

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a composition of sodium fluoride or a gray top

2mg/ml of blood or iodoacetate

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a composition of sodium fluoride or a gray top - 2mg/ml of blood or iodoacetate

functions to __

inhibit glycolysis and prevent most glucose consumption by RBC (good for 24 hours up to 48 hrs)

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the function of sodium fluoride is the

chelation thus the binding of ca and mg which inhibits ____

inhibition of enolase

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Precautions in sample collection to prevent glucose utilization by leukocytes (WBC)

true or faslse

true

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The sample should be kept cool; loss on standing in a warm room maybe as high as ___

10 mg/dL (0.6 mmol/L)/ hr

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in OGTT, we can use what type of samples>

urine and serum

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what are the substances we can add in urine to detect glucose?

5 mL glacial acetic acid
5g sodium benzoate for 24 hr specimen
Chlorhexedine –inhibit bacterial decomposition
0.1% sodium nitrate w/ 0.01% benzethonium chloride - antibacterial

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Requested during insulin shock and hyperglycemic ketonic coma (type 1 DM)

Random Blood Sugar

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increase glucose plus increase ketone bodies

hyperglycemic ketonic coma

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The test should be performed after an 8 hour fast

Fasting Blood Sugar (FBS)

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the most common test for glucose

Fasting Blood Sugar (FBS)

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Common for detecting diabetes mellitus

Fasting Blood Sugar (FBS)

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normal fasting glucose level

70-99 mg/dl or 3.9-5.5 mmol/L

impaired fasting glucose level

100-125 mg/dl or 5.6 - 6.9 mmol/l

impaired fasting glucose level

> 126 mg/dl or >7mmol/L

The test is performed two hours after meal

Two-hour post prandial test (PPBS)

how well the body will metabolized glucose

Two-hour post prandial test (PPBS)

Used to determine how well the body metabolizes glucose over a required period of time

Glucose Tolerance Test/ OGTT

Used for diagnosis of gestational diabetes

Glucose Tolerance Test/ OGTT

Not generally recommended for routine clinical use for diagnosis of DM

Glucose Tolerance Test/ OGTT

the recommended dose for OFTT based from WHO

75 mg/dl

2 types of GTT

Oral Glucose Tolerance Test Intravenous Glucose Tolerance Test

the most common oral glucose tolerance test

Janney-Isaacson Method (Single Dose Method)

a gtt that are usually for admitted patients

Intravenous Glucose Tolerance Test

Used for DM patients with gastrointestinal disorders

Intravenous Glucose Tolerance Test

in intravenous glucose tolerance test, how many gram of glucose are given per kg of body weight?

0.5 g 0.5 g of glucose/kg of body weight

an oral glucose tolerance test that is Divided Oral Dose or Double Dose Method)

Exton Rose Method

Requirements for OGTT

Patient must be ambulatory Patient to be tested should ingest at least 150g of CHO 3 days prior to testing Patient should not eat food, drink tea, coffee or alcohol, vigorously exercise, or smoke cigarettes during the test Patient must fast the night before the testing is performed

Procedure for OGTT

Collect the fasting blood sample Instruct the patient to drink the glucose load Collect blood sample after 1˚, 2˚ and 3˚

categories of OGTT

NORMAL GLUCOSE TOLERANCE - < 140 mg/dl IMAPARED GLUCOSE TOLERANCE - 140 - 199 PROVISIONAL DIABETES - > 200

criteria used to diagnose diabetes

fbs level 2 hr postprandial symptoms of hyperglycemia hbA1c greater than 6.5%

FBS level that is greater than or equal to ___ on at least 2 occasions is an indication of diabetes mellitus

126 mg/dL (7.0 mmol/L)

Two-hour postprandial glucose greater than ___

140 mg/dL (7.8 mmol/L).

Symptoms of hyperglycemia which include: ___

polyuria, polyphagia, polydipsia, unexplained weight loss plus a casual or RBS level of greater than or equal to 200 mg/dL (11.1 mmol/L)

A two-hour postload glucose of___ or greater than in an OGTT

200 mg/dL

HbA1C of greater than or equal to __

6.5%

a monitoring test for diabetes mellits that is Determined once in 3 months

Glycosylated Hemoglobin

1% increase in HgbA1C  means

35mg/dL (2 mmol/L) change in plasma glucose

ideal value for hba1c

<7% 

Factors affecting HBA1c

Average glucose concentration RBC life span

7% in hba1c estimated average glucose

154 mg/dl

Specimen requirement: for hba1c

EDTA whole blood sample - hemolysate

hba1 will measure the hemoglobin of our blood for a span of 3 months through the concept of ___ which is about lysing the rbc

hemolysate

2 Categories of HbA1c

Charge differences Structural characteristics of glycogroups on hemoglobin

a category of HbA1C that is about the cation exchange chromatography, electrophoresis, isoelectric focusing

Charge differences

a category of HbA1c that is about the affinity chromatography and immunoassay

Structural characteristics of glycogroups on hemoglobin

preferred method for hba1c

Affinity chromatography

HbA1c attaches to the boronate group of the resin and is selectively eluted from the resin bed using a buffer

Affinity chromatography

the reference method for hba1c

hplc - high performance liquid chromatography

HbA1c attaches to the boronate group of the resin and is selectively eluted from the resin bed using a buffer

Affinity chromatography

a monitoring test for diabetic mellitus that is conducted Once in 3 weeks

Fructosamine

Fructosamine is also known as

Glycosylated albumin

Affected by albumin levels

hypoalbuminemia > decreased glycated albumin

Fructosamine can't be conducted with patient wth what diseases

Liver disease Malabsorption Burns Nephrotic syndrome

Glucometer's principle

Glucose oxidase-peroxidase chromogenic reaction

factor of glucometer

Factor: 1.11

Factors affecting accuracy and reproducibility of glucometer

User variability hematocrit - the presence of anemia (false increase); polycythemia (false decrease Defective reagent strips and instrument malfunction Other variables: altitude, temperature, humidity, hypotension, hypoxia, high triglyceride concentrations

intermediates of glucose

ketones

Specimen for ketones

fresh serum/urine

test for ketone

gerhardt's test

end color of gerhardt's test

red solution

in ketones Gerhardt’s Test = _____ + ____ acid --> red solution

ferric chloride + acetoacetic

Copper Reduction Methods for blood glucose

folin wu method nelson-somogyi method neocupreine method benedict's method/fehling's reagent

a copper reduction method that uses PMA

Folin Wu Method

a copper reduction method that is Accurate but labor intensive and difficult to automate

Nelson-Somogyi Method

in Nelson-Somogyi Method, Cu+ reduces AMA to ___

molybdenum blue

a copper reduction method that will result to a yellow orange end product

Neocupreine Method

Ferric Reduction is also called as

hagedorn jensen

Inverse colorimetry

ferric reduction

Ferric Reduction (Hagedorn Jensen) is from color ___ to ___ at what nm

yellow to colorless measured at 400 nm

Dubowski Method - ___ method

o-toluidine method

Most sensitive method

Dubowski Method

Uses acetic acid

Dubowski Method – o-toluidine method

___ is carcinogenic and poisonous

O-toluidine

Dubowski Method – o-toluidine method is measured at ___

630 nm

In dubowski method Glucose + O-toluidine -> ____

Glycosylamine (colored green)

a method that is very specific to a substrate

enzymatic method

____ – first enzymatic reaction used

Glucose oxidase method

H2O2 measurement

a. Trinder’s method b. peroxidase method

O2 is measured by:

a. Clark electrode b. Ortho-dianisidine method

an O2 method that is initially colorless but when exposed to O2 becomes orange-brow

Ortho-dianisidine method

Disadvantage of Glucose Oxidase Reaction

Glucose oxidase can only measure beta glucose

2 types of glucose

Alpha-glucose Beta glucose

Alpha-glucose Beta glucose give the percentage of both

* Alpha-glucose = 35% cannot be oxidized * Beta glucose = 65% the only type which can be oxidized

enzymatic method that can interfere than other methods

HEXOKINASE METHOD

Generally accepted method for measuring glucose

hexokinase method

disadvantage of hexokinase method

hemolyzed samples can pose problem because contents from RBCs may interfere with the stoichiometric relationship between glucose and NAD(P)H accumulation

Uses alkaline ferricyanide reagent

Autoanalyzer method

Gave falsely high results because several compounds in serum alse were oxidized by ferricyanide

FERRICYANIDE METHOD

FERRICYANIDE METHOD is read at

400 nm

Cellular Strip

Dextrostics

Used in establishing correct insulin amount for next dose

dextrostics

Widely used as a method of screening for hypoglycemia of the newborn

dextrostics

Employs a paper strip impregnated with an enzyme-chromogen system

dextrostics