T4 - L3 Diagnosis of autoimmune diseases Flashcards
Diagnostic tests should be used to answer specific questions and/or to support a clinical
diagnosis and not as screening tools, why is this\/
we will get false positives
what is sensitivity?
measure of how good the test is in identifying the
disease
what is specificity?
measure of how good the test is at correctly defining people without the disease
what is a true positive?
test is positive
disease is positive
good sensitivity
what is a false negative?
test is negative
disease is positive
should retest
what is a false positive?
test is positive
disease is negative
what is a true negative?
test is negative
disease is negative
what is meant by the positive predictive value?
The proportion of people with a positive test who have the target disorder.
what is meant by the negative predictive value?
The proportion of people with a negative test who do not have the target disorder.
what are the two types of diagnostic test?
non-specific:
- inflammatory markers
disease-specific:
- autoantibody testing
- HLA typing
list some non-specific markers of systemic inflammation
inflammatory markers:
ESR CRP Ferritin Fibrinogen Haptoglobin Albumin Complement
what does the inflammatory marker ESR measure?
Erythrocyte sedimentation rate
- rate at which erythrocytes separate from the plasma
- higher the rate indicates inflammation somewhere in the body
what does the inflammatory marker CRP measure?
- C-reactive protein
- protein made by the liver and released into the blood as a result of tissue injury (infection/inflammation)
what does the inflammatory marker ferritin measure?
The ferritin concentration within the blood stream reflects the amount of iron stored in your body.
what does the inflammatory marker haptoglobin measure?
- free haemoglobin in the blood
- free haemoglobin only seen when RBCs are destroyed
- When large numbers of RBCs are destroyed, haptoglobin concentrations in the blood will temporarily decrease as the consumption of haptoglobin exceeds that produced by the liver.
