case unit 6 - diagnostics Flashcards
what does specificity test
how many people are healthy
what does sensitivity test
how many people actually have the disease
if the sensitivity is 84%
then 84% of people with the disease will be correctly tested as +ve
if the specificity is 53%
then 53% of healthy people will be correctly tested -ve
importance of a good diagnosis
correct and appropriate therapy can be prescribed
better prognosis
early detection
reasons why a diagnosis would be made
if a sick person visits the doctor
if an ‘at risk’ population gets screened
- clinical referral and subsequent tests may follow this
what types of measurements may be taken in a diagnosis
symptoms e.g. spots, fever physiology e.g. temp, bp blood-borne e.g. blood hormone/glucose levels biopsy-based e.g. cancer antigens other e.g. questionnaire, voc
what are VOCs
volative organic compounds
metabolic by-product of the disease present in swear, breath, urine, poo
disadvantage of measuring VOCs
each measurement could represent a combination of substances
why are VOCs a good diagnostic measure
non-invasive
quick
cheap
what is the diagnostic cut-off
vertical line between those that test +ve and -ve on rgpah
anyone above the cut off line has the disease
anyone below is healthy
overlap in the distributions gives false results
types of imaging used in diagnosis
x-rays
histology
karyotyping
disadvantages of imaging as a diagnostic tool
expensive
subjective
requires expert consultation
invasive - often used as an end diagnosis
use of automated diagnosis
e.g. detection of melanomas
AI used to recognise malignant moles from photo analysis
consultant standard
t-SNE visualtion used to detect different carcinomas
use of DNA as a biomarker if they think you have the disease
use PCR
sequence candidate genes for monogenic diseases
