POC devices for diabetes Flashcards
Can pharmacy technicians perform POC testing?
Yes,
pharmacist to interpret results
What are steps to perform POC?
- Purpose of POC
- Get consent
- Appropriate storage of devices
- Clean and safe environment
- Infection prevention procedures
- Document in patient record
- Notify primary care provider
How do glucometers work nowadays?
- Blood is drawn via capillary action
- Enzyme oxidizes glucose to gluconolactone
- either glucose oxidase or dehydrogenase - Electrons from glucose transferred to oxidized mediator molecule (mediator becomes reduced)
- Mediator delivers electrons to an electrode
- Electrode quantifies NUMBER of electrons
–> BG reading
What are cofactors responsible for in the glucometers?
What are the 3 options for co-factors?
Co-factors:
- transport of electrons from glucose to the mediator
PQQ (pyrrolo-quinoline quinone)
FAD (flavin adenine dinucleotide)
NAD (nicotinamide adenine dinucleotide)
How ACCURATE do glucometer readings have to be if reading UNDER 5.6mmol/L? OVER 5.6mmol/L?
UNDER 5.6mmol/L?
- 95% must be within +/- 0.8mmol/L
OVER 5.6mmol/L?
- 95% must be within +/- 15%
How PRECISE do glucometer readings have to be if reading UNDER 5.6mmol/L? OVER 5.6mmol/L?
UNDER 5.6mmol/L
- SD less than 0.3mmol/L
OVER 5.6mmol/L
- Coefficient of variance (CV) <5%
CV= SD/mean
What can cause falsely HIGH readings in glucometers?
THAABU
Triglycerides >5000mg/dL
Hematocrit <20%
Acetaminophen >8mg/dL
Ascorbic acid
Bilirubin >20mg/dL
Uric acid >10-16 mg/dL
What can cause falsely LOW readings in glucometers?
- Hematocirt >55%
What is the MOA of falsely high readings?
Acetaminophen , uric acid, ascorbic acid, bilirubin are oxidized instead of mediator (ferrocynaide),
- increases electrons –> higher BG reading
How to test for peritoneal dialysis patients? What is the issue?
Some glucometers read maltose as glucose
- causes high BG readings
What test is used for glucose in urine?
Diastix
How do Diastix work?
- Patient urinates directly on strip
- Glucose is oxidized by glucose oxidase to form - Gluconic acid + hydrogen peroxide
- Hydrogen peroxide oxidizes potassium iodide to form an iodine complex –> coloured product
- Color is compared to chart
What interferes with Diastix (glucose in urine) (3)
- Ascorbic acid
- Urine with high specific gravity
- Ketone bodies
What are disadvantages of glucose in urine tests? (5)
- Inability to detect hypoglycemia
- Many possible drug interferences (SGLT2)
- Lack of correlation with BG levels
- Difficulty in reading tests
- More privacy required
How does continuous glucose monitoring test for glucose?
Sensor inserted under skin that measures interstitial glucose
- sends readings to monitor
Advantages of continuous glucose monitoring tests
- Alarms when glucose levels are too low/high
- tracks glucose trends too
disadvantages of continuous glucose monitoring tests
Sensor must be replaced every few days
levels may “lag” with interstitial measurement vs blood measurement
How do flash glucose monitoring test glucose? Advantages
Same as continuous glucose monitoring (interstitial glucose)
- may not require calibration
- no alarms
What are the benefits of POC A1C testing vs lab testing (4)
- results obtained during patient visits
- NO DELAYS in adjusting treatment regimens
- Save the patient a trip to the lab
- Accurate readings
What can interfere with A1C measurements?
- Hemoglobinopathies
- Anemias ex. sick cell anemia
- Antioxidant supplementation ex. vit E, C
- Elevated bilirubin, triglycerides
Drugs - ASA
- Caffeine
- Acetaminophen
- Hydroxyzine
When are ketone bodies present in elevated glcuose?
During fasting
Prolonged exercise
High-fat diet
when insulin is lacking
When should ketone urine testing for diabetes be tested? (4)
- Acute stress/illness
- Consistently elevated BG readings
- During pregnancy
- Symptoms of DKA: Nausea, vomiting, abdo pain
What do ketones measure?
Acetoacetic acid
What is the reaction for ketone tests?
Acetoacetic acid reactions with nitroprusside to produce a coloured (lavender) substance
- compare colour to reference chart
What are reasons for false positives of urine ketone tests? (2)
- drugs with sulfhydrol groups such as captopril, n-acetylcysteine
- Acetoacetic acid still present in urine after blood levels normalize
What are reasons for false negatives of urine ketone tests? (1)
Ascorbic acid - vit C
What do ketones in capillary blood tests measure?
B-hydroxybutyrate
What do the at home cholesterol measuring devices measure?
Total cholesterol
What are the professional use cholesterol devices called?
Cholestech, cardio check
How do the professional cholesterol devices work?
Use enzymatic reactions to produce coloured substances and photometric detection
What do Cholestech LDX measure?
- Total cholesterol
- HDL-C
- triglycerides
- LDL-C
- glucose
- alanine aminotransferase
What do Cardiocheck PA measure?
- Total cholesterol
- HDL-C
- triglycerides
- LDL-C
other strips available that can measure glucose and ketone
What are the interfering substances for cholesterol-measuring devices
Many interfere
interference is less than 10%
