Download Glucose Measurements

Clinical Pathology
Laboratory Activity EMS 2012
• Blood Glucose Measurement
•Kketone and Glucose Urine Exam
•Blood Gas Analysis
•Cholesterol Examination
•Cortisol Measurement
Factors influencing laboratory results
Pre analytic
Analytic
Post analytic
Glucose Measurements
SPECIMEN CONSIDERATIONS
Whole
Pleural
Plasma Serum
blood
fluid
CSF
Urine
Glucose Measurements
Most measurements by enzymatic
methods:
1. glucose
dehydrogenase,
2. glucose
oxidase,
3. hexokinase
1. Glucose Dehydrogenase
2. Glucose Oxidase,
3. Hexokinase
(Henry JB. Clinical Diagnosis and Management by Laboratory Methods. 2011)
Glucose Measurements
• These reactions produce an electrical current
that is proportional to the initial glucose
concentration, or a product that measured
spectrophotometrically is proportional to the
initial glucose concentration.
• The assays can be initial rate-of-change assays,
where the velocity of the reaction is dependent
on the initial glucose, or end-point assays.
Glucosemeter
Spectrophotometer
POCT (point of care testing)/
Blood Glucose Home Monitoring/
Self Glucose Home Monitoring
Spectrophotometer
POCT (point of care testing)/
Blood Glucose Home Monitoring/
Self Glucose Home Monitoring
Method of POCT (point of care testing)/
Blood Glucose Home Monitoring/
Self Glucose Home Monitoring
Biosensor
Reflektansmeter
Biosensor Method
Biosensor Method
Reflektansmeter/ Amperometer
Method
A wide variety of devices are available for
home measurements:
• avoiding operator errors
• Calibration
• Errors that may contribute to inaccurate readings in certain
devices include the application of :
- an insufficient volume of blood
- milking the finger to acquire sufficient blood
- the use of outdated test strip
- environmental factors (humidity, heat, altitude)
- the use of a malfunctioning meter
- the use of a dirty meter
- hypertriglyceridemia
- hypotension
- measurements outside of the hematocrit or temperature range
Influecing Factors
• Influenced by high levels of salicylate,
acetaminophen, levodopa, uric acid, bilirubin,
lipids, or low oxygen levels, and others are
altered by touching the reaction area.
• Vit C, lactose, manose, galactose, xylose .
Reference Value
Ketone and Glucose Urine Exam
Dipstick Urine Test/ Strip
Urine test strip:
Rapid, easy, specific,cheap
SPECIFIC GRAVITY
PROTEIN
NITRITE
KETOBODY
GLUCOSE
UROBILINOGEN
BLOOD
PLASTIK ROD
NYLON COVER
TEST FIELD
(PAPER CONTAIN REAGENT)
FILTER PAPER
DIPSTICK TEST
Dipstick urine test
1. Specific gravity
2. pH
3. Leukocytes
4. Nitrates
5. Protein
6. Glucose
7. Ketones
8. Urobilinogen
9. Bilirubin
10. Blood
Glucose (negative)
Glucose is normally present in glomerular filtrate, but it is
reabsorbed by the proximal tubule.
D-Glucose + O2
H2O2 + 0-tolidine
GOD
POD
δ-D gluconolactone + H2O2
H2O + colour
Ketones (negative)
in healthy individuals, ketone bodies are formed in the liver and
are completely metabolized so that only negligible amounts
appear in the urine
sodium nitroprusside and glycerin + acetoacetate and acetone
alkaline medium
violet dye complex.
URINALYSIS STEPS
 PRE-ANALYTIC : patient preparation, samples collection,
samples handling, labelling, refrigeration, preservatives of urine
specimens.
 ANALYTIC: principle of procedures, measurements,
interpretation, conventional & rapid and sophisticated
 POST-ANALYTIC: recording, reporting, use of units :
conventional unit and international unit
 QUALITY CONTROL (QC):calibration, control solution
to get good and reliable results
Pre-Analytic
1.
-
-
Specimen collection
Requisition form  must accompany with specimen
delivered to the lab; the form include : patient’s name, I.D
number, date and time of collection and additional
information : age, location, physician’s name, type of
specimen/method, interfering medication and clinical
information
Container  clean, dry, leak proof, disposable
All specimens must be properly labeled  must be attach
to the container, not to the lid, should not become
detached if the container is refrigerated
The information on form requisition  match with the
inform on the label
Labelling urine specimen
Name (min 2 initial, ex: Deni Darmawaty)
Sex : female
Date (day, month, year)
Time collection:
Adress and telp number :
Pre-Analytic
Two Type of Specimen
 Based on Time :
- Random specimen
- First morning/fasting specimen
- 2-hours post prandial specimen
- Timed urine (12-hours, 24-hours specimen)
 Based on method :
- Midstream Clean-Catch specimen
- Catheterized specimen
- Suprapubic aspiration
Type of Urine Specimens
Purpose
Random
Routine screening
First morning
Routine screening
Pregnancy tests
Orthostatic protein
Fasting (second morning)
Diabetic screening/monitoring
2-h postprandial
Diabetic monitoring
Glucose tolerance test
Accompaniment to blood samples in
glucose tolerance test
24-h (or timed)
Quantitative chemical tests
Catheterized
Bacterial culture
Midstream Clean-catch
Routine screening
Bacterial culture
Suprapubic aspiration
Bladder urine for bacterial culture
Cytology
• The first morning urine:
Collected upon rising, it represents the urine over
approximately an 8 hour period
• Ad random urine:
Collected any time
• The 2-hour postprandial urine:
Collected 2 hour following the meal ( for urine glucose)
• The 24-hour urine:
A pooling of all urine excreted by the patient over a 24 hour period
(for protein, uric acid, calsium quantitation, etc)
• Midstream urine:
The middle portion of a single urination
Pre-Analytic
3. Specimen Handling
Folowing collection  should be
delivered to the lab promptly and tested
within 1-2 hours
If it can’t delivered  must be
refrigerated or add with chemical
preservative
LIMITATION OF THE METHOD AND
INTERFERING FACTORS:
• Highly pigmented or large amounts of levodopa
metabolites in urine may cause weak positive result
• High Specific Gravity and low pH urine and PSP
(phenolsulfophthalein) may cause false positive result
• High-protein, carbohydrate-free, high-fat diets may
result in ketonuria (false posi- tive)
• Medications : phenazopyridine , ascorbic acid, ether,
insulin, isopropyl alcohol, metformin, isoniazide,
isopropanol, paraldehyde, valproic acid, and
bromsulfoph- thalein also can cause false positive
results
EXPECTED VALUE
• In starvation diets or in other instances of
abnormal carbohydrate metabolism, ketone
appear in urine in excessively large amounts
before serum ketone are elevated.
• This test detected 5 mg/dL of aceto-acetic
acid; 70 mg/dL acetone; but more specific for
aceto-acetic acid.
Lipoprotein structure