Clinical Lab Data Flashcards
define accuracy
agreement between measured quantity and true value
define precision
agreement between repetitive measures
_________ is a test of reproducibility
precision
3 measures of precision
arithmetic mean
standard deviation
coefficient of variation
explain what coefficient of variation is
expresses standard deviation as a percentage of the mean
standard deviation/sample mean
measure of PRECISION
What confidence intervals are used to determine whether 2 tests can be used, solely based on how precise they are?
95% confidence intervals, plus minus 2 standard deviations
what are the 2 most important factors for reference intervals
gender and age
can a healthy person have an abnormal lab test value?
yes, bc reference intervals are designed to include 95% of the values from a healthy reference population, there is a 5% chance
true or false
abnormal results are a consequence of multiple testing
true
sensitivity refers to…..
the% of positive test results in patients with a particular disease
a sensitivity of 95% means…….
95% of patients with the disease will be affected by the test
5% with the disease will have false negative results
what is specificity?
refers to the % of negative test results in patients WITHOUT a particular disease
a specificity of 95% means….
95% of patients WITHOUT the disease will have a negative result
5% of patients WITHOUT the disease will have a false positive result
prevalence is defined as….
the % of the general population who have the disease
expressed as # of people with the disease per 100,000 people
what is a screening test
a test used to screen a population of people for the presence of a particular disease
screening tests that are performed on unselected populations in which disease prevalence is very low will yield……
overwhelmingly false positives even if the test has a very high specificity
CBC vs CBC with differential
CBC with differential includes types of WBC
in a CBC with differential, presence of _____ is an indicator of immune system status
lymphocytes
in a CBC with differential, _____ is an indicator of the ability to manage infection
granulocytes (neutrophils, bands)
the normal ratio of CD4:CD8 is….
2
what measures ALL phases of coagulation?
bleeding time
what measures the extrinsic clotting pathway?
prothrombin time (PT)
what measures the intrinsic clotting pathway?
partial thromboplastin time (PTT)
_______ is increased by administration of coumadin
prothrombin time (PT)
________ is increased by administration of heparin
partial thromboplastin time (PTT)
when would chloride levels be elevated
in dehydration
when would sodium levels be elevated?
dehydration
hyperaldosteronism
when would sodium levels be decreased?
by sweating
abnormal levels of potassium are associated with…..
myocardial infarction
potassium levels may be elevated in what 2 scenarios?
adrenal insufficiency
renal failure
potassium levels may be depressed due to what 3 scenarios
malabsorption
starvation
diuretics
carbon dioxide levels are elevated when?
in emphysema
when are carbon dioxide levels depressed?
starvation
diarrhea
diabetic acidosis
when is BUN (blood urea nitrogen) elevated?
in impaired renal function
when is BUN (blood urea nitrogen) depressed?
in liver damage
when would creatinine levels be elevated
in impaired renal function
when are glucose levels elevated
diabetes mellitus
in what 3 scenarios would glucose levels be depressed
pancreatic disorders
endocrine disease
liver disease
low levels of _______ are an acute medical emergency
glucose
true or false
high levels of glucose are an acute medical emergency
FALSE
low levels
high values may be better tolerated dep on usual levels of the pt
elevations in liver enzymes are associated with….
liver damages like hepatitis and cirrhosis
name 4 liver enzymes
lactate dehydrogenase
alkaline phosphatase
aspartate aminotransferase
alanine aminotransferase
urinalysis may be useful to assess……
renal function
what ph should the urine be
4.5-8.5
true or false
the urine should not have any cells in it
true
____ and ____ should be negative in the urine
glucose
microalbumin
what are therapeutic drug levels?
measures the blood levels of ingested meds
elevated levels may be toxic
what accounts for most of the excess mortality associated with diabetes?
macrovascular disease - complications related to accelerated atherosclerosis in large-medium arteries
microvascular disease is also a long term complication of diabetes.
what is it?,
occurs in smallest arteries, arterioles, and capillaries
includes diabetic neuropathy, nephropathy, cardiac dysfunction, diabetic retinopathy
how is diabetes mellitus diagnosed
symptoms
examination of random or of fasting blood glucose
blood glucose testing is performed mainly on…..
venous plasma
explain how glycemic control is monitored
daily self monitoring of blood glucose conc
bi-monthly - quarterly: HbA1c
explain what HbA1c is a measure of
provides an index to the “average” plasma glucose over the preceding 2-3 months
what is the normal HbA1c level?
what is it in diabetic patients?
normally less than 6%
in diabetic patients it can increase 2-3 times
how is HbA1c formed?
by the non-enzymatic attachment of glucose to haemoglobin
slowly and continuously formed
_______ is a major complication if insulin dependent diabetics.
it may progress to…..
diabetic nephropathy
may progress to end-stage renal failure
how is microalbumin detected?
by sensitive immuno assays
why is testing microalbumin important for diabetic patients?
if detected early, it can allow the reversal of nephropathy
bc once proteinurea happens, treatment may slow progression of kidney disease but CANNOT be reversed at this point
what are the most commonly disturbed electrolytes in congestive heart failrure?
sodium
potassium
chloride
CVA (stroke) and valvular heart disease - what test is performed
coagulation studies
in liver disease, what 2 things are examined
liver enzymes
coagulation studies
in renal disease what 2 things are examined
electrolytes
urinalysis
in respiratory disease what is examined
electrolytes
what are test kits used for?
used to identify bacteria within 24-48 hourd
explain how bacterial test kits work
microtubes contain dehydrated substances inoculated with suspension
they are incubated and any color change means enzymatic activity or carbohydrate fermentation
as sensitivity increases, what happens to specificity?
it decreases
