Week 2: Urine and blood glucose analysis Lab Flashcards
How long does it take after a meal for blood glucose for return to normal after a meal?
2 hours
What is renal threshold?
The level of blood glucose at which glucose will also be excreted into the urine.
In normal non-diabetic patients this level is never normally met
~10mmol/L
What do blood glucose tend to look like in diabetics?
Higher and more sustained in diabetics
Often goes over the renal threshold - glucose appears in urine
What is the oral glucose tolerance test?
Used to diagnose suspected T2 Diabetes
Patient is asked to fast for 8-12hours before the test
Blood sample is taken
Given a known conc glucose drink
After two hours the blood glucose sample is taken again
Level is sample is compared to expected levels for functional glucose processing
What are the normal changes in glucose/insulin levels after a meal?
Sharp rise in glucose levels
Slow rise in blood glucose that is then slowly decreased back to normal within 2 hours of the meal
Insulin peak is higher than glucose peak and only slightly delayed
Insulin levels are always higher than glucose levels
How changes are expected in blood glucose/insulin in a diabetic after a meal?
Higher starting glucose
Rapid and greater increase in blood glucose
Much smaller, delayed and lower increase in insulin (which remains much lower than glucose)
Returns to normal level within 5 -6 hours
Glucose levels are always higher than insulin levels
What plasma glucose level is indicative of a diagnosis with diabetes?
11.1 mmol/L
What is the difference between capillary whole blood and plasma?
CWB - greater proportion of Hb and haemetrocrit
Plasma - liquid that contents of blood are suspended in, typically taken from the vein
What are the normal ranges of glucose in capillarly whole blood in fasting and 2 hours after a meal?
fasting: 3.5-5.9 mmol/L
2 hours: 3.5-6.0mmol/L
What are the diabetic ranges of glucose in capillarly whole blood in fasting and 2 hours after a meal?
Fasting: Above 6.0 mmol/L
2 hours: 11.1 mmol/L
What are the normal ranges of glucose in plasma in fasting and 2 hours after a meal?
Fasting: below 5.5 mmol/L
2 hours; below 7.8 mmol/L
What are the diabetic ranges of glucose in plasma in fasting and 2 hours after a meal?
Fasting above or equal to 7 mmol/L
2 hours above or equal to 11.1 mmol/L
How to do a urine dipstick?
Keep tube over blue loo roll
Dip stick in for short period of time.
Slowly draw out.
Compare to normal values on the side of the tube
What can be measured on a urine dipstick?
Glucose
Ketones
Specific Gravity
Blood
pH
Protein
Nitrite
Leukocytes
What is the normal of glucose in urine?
Negative
What is the normal of ketones in urine?
Negative
What is the normal of specific gravity in urine?
1.002-1.035 mOsm/kg
This is a mesure of the concentration of solutes in the urine
What is the normal pH of urine?
4.5-8
What is the normal protein in urine?
Negative
What is the normal nitrite in urine?
Negative
What is the normal leukocytes in urine?
Negative
What should be disposed of in the soft chemical waste bin?
Non-sharp and non infectious material such as gloves and blue roll
Describe how you would create a calibration curve in order to estimate glucose concentration in a solution>
Use a standard glucose solution to create dilution of known glucose concentration
Add glucose oxidase to the solutions, H2O2 will be produced, add a brown dye and a second enzyme peroxidase, if H202 presents brown dye will turn pink.
Uses a calorimeter to measure the absorption of the solution, this is proportional to the amount of pink hence glucose.
Higher conc is less absorbance -plot on graph absorbance on the y and glucose conc on the x. Draw a calibration curve.
Repeat with patient samples, adding same enzymes and dye, ensure same volume of samples and additives used through out.
Match absorption to point on curve then follow down to find glucose concentration
Why is the number of patient samples provided important?
Clinically must be repeated on at least two different patient samples to have a positive diabetes diagnosis.
Often compare two fasting and fed glucose concentrations to understand baseline levels and the effectiveness of insulin (better demonstrated at fed).
How would you take a patients capillary blood glucose reading?
Wamr hand
Wipe area to be punctured with an alcohol wipe and allow it to dry
Turn on glucose analyser - ensure code matches the code on the test strips
Insert the test strip by pushing into slot at the base of the glucometer
Use lancet - remove needle cap and push into skin
After using lancet dispose in sharp bin
Wipe away first drop of blood with a tissue
Milk for a second drop of blood
Touch the edge of the test strip to the blood - blood will be absorbed up the test strip
Apply pressure to the puncture wound and ask the patient to hold on pressure until bleeding resolves
Dispose of waste in the appropriate bins (capillary in sharps), clean work bench and analyser
What factors may influence blood glucose results?
Why is this important clinically?
Dietary intake - high v low glycemic index foods
Pancreas function - beta cells unable to produce insulin (type 1 diabetes)
Cells resistant to insulin - type 2 diabetes
Medication - prescribed steroids, statins and acne treatment can increase blood glucose, also OTC medication such as cough syrups can increase blood glucose
How do you test a urine sample from a patient?
Compete over blue roll to prevent spillages
Dip all of test pad strips into the urine and remove immediately
Drag the edge of the strip along the lip of the bottle to remove extra urine
Check pads by comparing to standards on the bottle in the most time sensitive way - some require a shorter amount of time before needing checked
Record results
Dispose of test strip in orange waste bag
What is the average specific gravity reading in urine?
1.002 - 1.035 mOsm/kg
What factors may impact blood glucose?
Food/fasting
Physical activity
Alcohol - decrease
Coffee - elevated for longer
Dehydration
Stress - increase
infection - conflicting evidence, generally thought to increase energy expenditure
Medication
Menstraul cycle - variation by person, typically increases a f ew days before
Pregnancy - increases
