Diagnostics and Laboratory Testing Flashcards
Diagnostic efficacy
does the test correctly identify abnormalities?
Diagnostic effectiveness
does the test change your diagnosis?
therapeutic efficacy
does the test change your management?
therapeutic effectiveness
does the test change the patient’s outcome?
sensitivity
true positive rate
how accurate is it to give the result I’m suspecting
want 90% sensitivity
specificity
true negative rate
tells you the patient doesn’t have it/they have a negative result
want 90% specificity
an asymptomatic patient with abnormal results
does not equal significant disease
likelihood ratio
describes the proportion of accurate and inaccurate positive test results
LR = sensitivity / (1-specificity) or TP rate/ FP rate
likelihood ratios greater than 10 provide ___
considerable confidence
tests part of the CBC
RBC, red blood cell indices (MCV, MCH, MCHC, RBC distribution width), WBC, platelet count
RBC normal values (males and females)
males: 4.7 -6.1 x 10^6 / uL
females: 4.2 - 5.4 x 10^6/uL
Hemoglobin normal values (males and females) and critical values
males: 14 - 18 g/dL
females: 12 - 16 g/dL
critical values: <5 or >20
Hematocrit normal values (males and females) and critical values
males: 42 - 52%
females: 37 - 47%
critical values: <15% or > 60%
MCV normal value
80 - 90 fL
MCH normal value
27 - 31 pg
MCHC normale value
32 - 36 g/dL (32% - 36%)
RBC distribution width normal value
11 - 14.5%
WBC normal value and critical values
5 - 10 x 10^9/ L
critical: <2.5 or >30
Neutrophils normal value
55-70%
Lymphocytes normal value
20-40%
Monocytes normal value
2-8%
Eosinophils normal value
1-4%
Basophils normal value
0.5 -1%
Platelet count normal values and critical values
150 -400 x 10^9/L
critical: <40 or >1000
thrombocytopenia numeric value
<100 x 10^9/L
thrombocytosis numeric value
> 400 x 10^9/L
thrombocythemia numberic value
> 1000 x 10^9 /L
if less than _____ , hesitate to put in epidural/spinal in due to risk of _____
100,000
hematoma that could compress the cord
when are coagulation studies indicated?
patients taking anticoagulants, liver disease, coagulation disorder, and malnutrition
are coagulation studies predictive of perioperative bleeding?
no
which clotting factor is not made in the liver?
Von Willebrand Factor
what tests are considered coagulation tests?
activated clotting time, bleeding time, platelet count, PT, aPTT, INR, Ecarin clotting time
PT normal value
12 - 14 seconds
aPTT normal value
25 -32 seconds
Which test evaluates EXTRINSIC factor function?
PT and INR
Which test evaluates INTRINSIC factor function?
aPTT
INR normal value
0.8 - 1.1
Which coagulation study is the most accurate?
INR
ACT normal value
80 -150 seconds
Bleeding time normal value
3 - 7 minutes
Which patients/disease processes should you consider getting serum chemistry?
hepatic or renal disease, malnutrition, malabsorption, ETOH abuse, gastric bypass, anasarca
What tests are included in the serum chemistry?
sodium, potassium, carbon dioxide, calcium, chloride, glucose
Na+ normal values
135 - 145 mEq/L
K+ normal values
3.5 - 5.0 mEq/L
CO2 normal values
23 - 29 mEq/L
Ca++ normal values
8.5 - 10.5 mg/dL
Cl- normal values
96 - 106 mmol/L
Glucose normal values
fasting: 70 - 99 mg/dL
postprandial at 2 hours: <140 mg/dL
What other patients/disease processes might you consider checking renal function tests on?
diabetics, hypertension, family history, elderly, taking diuretics, when radiographic dye will be used
What tests are included in renal function tests?
BUN, creatinine, eGFR
BUN normal values
5 - 25 mg/dL
creatinine normal values
0.6 - 1.2 mg/dL
which test is the most accurate reflection of renal function?
creatinine clearance
it is a reflection of GFR
pregnancy testing may be valuable in ____
pediatric patients having menses, poor historians, irregular periods, undergoing infertility treatment
what is the most frequently ordered preoperative test?
ekg
MET desirable score
> 4 (ability to climb two flights of stairs)
key to determining need for preop cardiac testing
