MSK lab medicine Flashcards
(37 cards)
Define specificity
ability of a test to correctly identify those WITHOUT disease
A measure of the ‘true negative’ rate
Define sensitivity
ability of a test to correctly identify those WITH disease
a measure of ‘true positives’
What does SPIN stand for
Specific tests, when Positive, rules disease IN
What does SNOUT stand for
Sensitive tests, when Negative, rule diseases OUT
What is accuracy
measure of the closeness to the ‘true’ value
ability of a test to correctly measure what we intend it to measure
what is precision
measure of the reproducibility of the test
measure of the variation in test performance when other conditions are accounted for
What does reference range mean
the normal range (upper and lower limites of a lab test)
what does the reference range do for us
provides context to the lab results
What is a critical value for a test
a lab result that significantly outside the reference range which is a threat to health and requires urgent intervention
Define point of care testing
testing completed at the bedside, often by non-lab professionals and require smaller sample sizes than in-lab testing,
Rapid turnaround and used for real-time medical decision making
(i.e. urine dip, glucose test)
What is APR
Acute phase reactants
inflammatory markers that rise early in the disease process (ESR, CRP and Procalcitonin)
is APR specific or sensitive
sensitive because they can not reliably be used to distinguish between the causes of inflammation
What is CRP
high-sensitivity (more sensitive than ESR) as it rises in 12-24 hours and peaks in 2-3 days.
what level of CRP is highly suggestive of bacterial infection?
> 10mg/dL or >100mg/L
What does ESR stand for
Erythrocyte sedimentation rate
how does ESR trend?
rises in 24-48 hours and falls slowly over days to months to normalize
What does PCT stand for
Procalcitonin
How do PCT and ESR/CRP compare?
PCT is more sensitive and Specific than ESR/CRP
what is PCT specific to?
infectious etiologies not elevated in rheumatologic conditions
what is the trend for PCT?
rises in 3-4 hours, peaks in 6-24 hours
what does PCT monitor?
bacteremia -> sepsis
What are acid-fast bacilli
Mycobacterial species
M. tuberculosis, M. avium, M. bovis, M. Leprae, etc
These are rare joint pathogens on fluid analysis
What are the common fluids that you will analyze?
pleural - thoracenteiss
CSF - lumbar puncture
Synovial - aspiration/arthrocentesis
What information is gathered by a fluid analysis
visual characteristics of the fluid
viscosity
cell count/cytology
protein levels/LDH
Gram stain/culture
and situation specific tests such as crystals, AFB, PCR, synvosure
