Dr. Parsa - Intro to Lab Medicine Flashcards
A typical lab provides the foll healthcare services
- blood chemistry
- hematology
- Blood bank
- micro cultures
- urinalysis, serology
common reasons for ordering lab tests
- screen for disease
- diagnose a disease
- follow progress of disease
- monitor therapy
least number of false negatives/ positivity in presence of disease refers to
sensitivity
Negativity in absence of disease refers to
specificity
what is prevalence
percentage of people with disease in given population at a given point in time
What is the most significant parameter in determining predictive calue of positive test
prevalance
Higher specificity gives you higher ____ value
predictive
As prevalance increases:
true positives increase relative to false positives and false negatives increase relative to true negatives
what is the best cut off value
- one with the highest sensitivity (highest true positive rate)
- one with the highest specificity (lowest false positive rate)
A screening test is highly ___ (no FN), but not very specific (some FP)
sensitive
A diagnostic test is highly ____
specific (no FP)
What is parallel testing
ordering lab tests at the same time. If not normal, the chance the pt has the disease is negligible (low false negative rate= high sensitivity)
what is multiphasic testing
consists of multiple tests that cover a range of cell, tissue and organ functions ordered as a single panel
most indicative of sickle cell disease is:
reticulocyte (RBC production); Hb S polymerizes in hypoxic conditions and clog up blood vessels and form clots.
Sickle cell causes
- infarction: arterial vaso occlusion
- hemolytic: destruction of RBC with appropriate marrow response
- aplastic: destruction of RBC with marrow shut down
