Lecture 12: Basic Lab Principles Flashcards
What determines diagnoses most of the time?
Clinician’s judgment 50% of the time, followed by radiologic studies 30%.
What is the purpose of diagnostic tests?
Establishing a diagnosis in a symptomatic patient.
Screening for disease in an ASYMPTOMATIC patient.
Assessing/monitoring disease condition with an established disease.
Monitor therapy.
Confirm the ABSENCE of a disease.
Why is inappropriate testing dangerous?
It can increase the time it takes to diagnose.
Financial cost
Physical/emotional distress
Liability to followup on any abnormal results
Misdiagnosis/red herrings
False negatives/positives.
What should we consider when ordering a test?
Time
Money
Sensitivity/specificity
Risk
Does it even affect how I will treat the patient?
What factors can affect lab results?
Age
Gender
Race
Medications
Pregnancy
Food ingestion
Posture
Timing
What is the definition of a reference range?
The set of values that 95% of the population falls under for that parameter.
What is a better point of reference?
Previous lab values, not reference values.
What are some examples of common laboratory tests we run?
CBC
BMP/CMP
LFT (liver function panel)
TFT (Thyroid function panel)
Renal panel
Anemia panel
Why do we need to be careful of just ordering panels?
We may get results we do not need that have no clinical significance.
The panel may not be the best test.
What is included in a CBC?
WBC
RBC
Hgb
Hematocrit
RBC indices
Platelets
What is the difference between a CBC with diff and without diff?
The differential part gives us the specific counts of each type of WBC, such as a neutrophil, eosinophil, lymphocyte, etc…
When do we order a CBC?
Infection
Hematologic diseases
Blood losses
General screening
When do we order a CBC with diff?
When we are concerned with possible etiologies involving abnormal WBCs.
What is included in a BMP?
Glucose
BUN
Creatinine
Sodium
Potassium
Chloride
Carbon dioxide/Bicarb
Calcium
What is the difference between a Chem-7 and a BMP?
It is a BMP without calcium
