Metabolic Screening Flashcards
Type 1 diabetes:
primarily a result of pancreatic beta cell destruction causing impaired insulin secretion
Type 2 diabetes:
insulin resistance (insulin less effective at facilitating glucose uptake)
Gestational diabetes:
glucose intolerance onset during pregnancy
Glucose measurement is important for…
- diagnosis of diabetes
- monitoring glucose (at rest, during, and following exercise)
Normal blood glucose levels for capillary glucose sampling:
- fasting: 3.9 - 5.5 mmol/L (70-100 mg/dL)
- non-fasting: < 11.1 mmol/L (<200 mg/dL)
4 steps of capillary sampling (WHO guidelines):
- select and clean site with alcohol
- puncture the skin with 1 quick, deliberate poke (prevent repeated punctures)
- wipe away first drop of blood (avoid contamination with tissue fluid or debris)
- avoid squeezing the finger too tightly because this dilutes the sample with tissue fluid (plasma)
The same technique (capillary sampling) is used for…
- blood glucose
- lactate sampling
Where should the site be for capillary sampling?
- lateral aspect (least sensitive)
- do not use tip: can it bone
- pad of finger is thicker/harder
Why can capillary sampling be ineffective in some cases?
- 1 value is not relevant all day long
- doesn’t tell you how the body deals with glucose (value can be high or can be going up)
OGTT =
oral glucose tolerance test
OGTT:
- standardized test to see how individuals deal with glucose
- oral glucose tolerance beverage (standard 75g of glucose)
- need to take in 5 minutes
- healthy individual should be able to clear quickly
Disadvantage to OGTT:
doesn’t tell you anything about the rest of the day
Continuous glucose monitoring:
- patch on abdomen
- measures interstitial glucose (glucose that has exited circulatory system, good representation of what is in it)
Who would use continuous glucose monitoring?
- someone with diabetes (need data often)
- expensive, not covered
- some have alerts if it gets too high or too low
HBA1c =
glycated hemoglobin
RBC are freely permeable to ______ molecules.
glucose
Glucose irreversibly attaches to _______ to form ____ _____.
- hemoglobin
- glycated hemoglobin (HBA1c)
Because RBC has a life span of ____ days, glycated hemoglobin reflects glucose levels over the preceding ____ months.
- 120 days
- 2-3 months
The HBA1c fraction is abnormally _____ in people with chronic hyperglycemia.
elevated
A HBA1c > or equal to ____% is diagnostic of diabetes if confirmed by repeat testing.
6.5%
FPG =
fasting plasma glucose
Advantages of FPG:
- established standard
- fast and easy
- single sample
- prevents microvascular complications
Disadvantages of FPG:
- sample not stable
- high day to day variability
- inconvenient (fasting)
- reflects glucose homeostasis at a single point in time
Advantages of 2hPG in 75g OGTT:
- established standard
- predicts microvascular complications
Disadvantages of 2hPG in 75g OGTT:
- sample not stable
- high day to day variability
- inconvenient
- unpalatable
- cost
A1C =
glycated hemoglobin
Advantages of A1C:
- convenient (measure any time of day)
- single sample
- predicts microvascular complications
- better predictor of macrovascular disease than FPG or 2hPG in a 75g OGTT
- low day to day variability
- reflects long-term glucose concentration
Disadvantages of A1C:
- cost
- misleading in various medical conditions
- altered by ethnicity and aging
- standardized, validated assay required
- not for diagnostic use in children, adolescents, pregnant women, or those with suspected type 1 diabetes
Diagnosis of diabetes with FPG:
> or equal to 7.0 mmol/L
Fasting =
no caloric intake for at least 8 hours
Diagnosis of diabetes with A1C:
- not recommended
- > or equal to 6.5% (in adults)
- using a standardized, validated assay in the absence of factors that affect the accuracy of the A1C and not for suspected type 1 diabetes
Diagnosis of diabetes with 2hPG in a 75 g OGTT:
> or equal to 11.1 mmol/L
Diagnosis of diabetes with random PG:
> or equal to 11.1 mmol/L
Random =
any time of the day, without regard to the interval since the last meal
IFG =
impaired fasting glucose
IGT =
impaired glucose tolerance
Diagnosis of prediabetes with FPG:
- 6.1-6.9 mmol/L
- IFG
Diagnosis of prediabetes with 2hPG in a 75g OGTT:
- 7.8-11.0 mmol/L
- IGT
Diagnosis of prediabetes with A1C:
- 6.0-6.4%
- prediabetes
How to diagnose metabolic syndrome: > or equal to 3 of the following:
- elevated waist circumference
- elevated TG > or equal to 1.7 mmol/L
- reduced HDL-C < 1.0 mmol/L (male), < 1.3 mmol/L (female)
- elevated BP (> or equal to 130/85)
- elevated FPG > or equal to 5.6 mmol/L
What is required for phlebotomy?
separate certification
Phlebotomy:
taking blood
Normal range of hematocrit:
40-50%
Plasma should be ____% of total blood.
55%
Buffy coat leukocytes and platelets should be ___% of total blood.
< 1%
Erythrocytes should be ____% of total blood.
45%
Hemoglobin concentration normal range:
13-17 g/dL
Hemoglobin consists of:
- alpha chains
- beta chains
- O2 binding heme group
Hemoglobin oxygen saturation:
- Measures amount of hemoglobin not bound to oxygen
- Should be high 90s in most individuals
- Relevant for heart failure, exercise (aerobic power, how much oxygen is used)
Hypoxia during exercise:
- Females can’t ventilate enough with exercise
- Need to extract more from the blood = hypoxic
- If you give them oxygen, they will perform better
Urine tests can be used to show…
- Kidney function (Protein shows up when this fails)
- Ketosis (Protein shows up)
