glucose methodologies Flashcards
in a normal hematocrit, whole blood glucose level is ___ % lower than the plasma glucose
10-12%
Plasma glucose is __% lower than Serum glucose
5%
Capillary blood glucose: ___ higher than venous blood
2-5 mg/dL
possible samples we can use to check for glucose level
Serum, CSF, Whole Blood, Synovial Fluid, Urine
Standard specimen
Fasting Venous Sample
csf sample has how many percent of glucose
60%
Uncentrifuged coagulated blood
-can lower the glucose level for how many percent in 1 hr?
↓5-7% in 1 hour
Prolonged standing:___ lower
without refrigerator
7 mg/dL per hour (RT)
if the sample is refrigerated in 4*C, the glucose level will only lower down for ___ every hhr
1-2 mg/dl
Separated nonhemolyzed sterile serum
can last in 25*C for how many hrs?
8 hrs
Separated nonhemolyzed sterile serum
can last in 4*C for how many hrs?
72 hrs
serum should be separated from the clot within ___
.5 to 1 hr
a composition of sodium fluoride or a gray top
2mg/ml of blood or iodoacetate
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)
the function of sodium fluoride is the
chelation thus the binding of ca and mg which inhibits ____
inhibition of enolase
Precautions in sample collection to prevent glucose utilization by leukocytes (WBC)
true or faslse
true
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
in OGTT, we can use what type of samples>
urine and serum
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
Requested during insulin shock and hyperglycemic ketonic coma (type 1 DM)
Random Blood Sugar
increase glucose plus increase ketone bodies
hyperglycemic ketonic coma
The test should be performed after an 8 hour fast
Fasting Blood Sugar (FBS)
the most common test for glucose
Fasting Blood Sugar (FBS)
Common for detecting diabetes mellitus
Fasting Blood Sugar (FBS)
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
