Ability to accurately identify affected, as percentage--OR-- Percentage of affected that will test positive.
TP / TP+FN
Ability to accurately identify unaffected, as percentage--OR-- Percentage of unaffected that will test negative. TN / TN+FP
Positive Likelihood Ratio
The "odds" of being affected when test is positive.
Sensitivity / (1-Specificity)
Negative Likelihood Ratio
The "odds" pf being unaffected when test is negative.
(1-Sensitivity) / Specificity
Two classes of Pre-analytic FALT
In vivo (gender, age, race, diet, diurnal variation)
In vitro: specimen handling, sampling error)
CK-MB (CPK-MB) fx, use & value
Creatine Kinase MB. Phosphorylates creatine to make phosphocreatine. Cardiac marker @ >4.0 ng/mL
Elevated in MD, Skeletal muscle injury, malnutrition, post-marathon, rhabdomyolysis, prostate & breast cancer
cTn fx, use & values
Cardiac troponin. Regulates calcium binding in cardiomyocytes.Gold standard for ACS, establishes irreversible necrosis. cTnT: >0.1 ng/mL; cTnI: >0.04 ng/mL
Elevated in CHF, Aortic Dissection;
Hypotension, Arrhythmias, Rhabdo, Myocarditis (CHAD HARM)
Myoglobin fx, use and values
O2-carrying protein in skeletal & cardiac muscle. Earliest marker for AMI. Male: 28-72 ng/mL; Female: 25-58 ng/mL.
LDH fx, use and values
Lactate Dehydrogenase. Converts pyruvate to lactate, releasing NAD+. Late AMI marker.
RATIO of LDH1 : LDH2 > 1 suggests MI.
ASO fx, use & values
Antistreptolysin O. Antibodies to streptolysin-O (also streptokinase, hyaluronidase & DNAse-B) following Rheumatic Fever, Scarlet fever, glomerulonephritis .
Tests for GpA Strep Ix, which may suggest valve dz. Normal Adult: <100 IU/mL. Kids Normal kid: <260 IU/mL
Elevated after any Strep-A; Endocarditis, glomerulonephritis, & in healthy Strep-A carriers
Blood culture uses & procedure
Tests for bacterial Ix of pericardium (pericarditis) or valves (endocarditis). Most common bacteria are pnemococcus or TB. Pain worse supine, better w\sitting, leaning forward. Take 3 cultures from 3 locations, 2 of 3 must be positive in 3-7 days.
Brain Natriuretic Peptide fx & use
BNP is made by the ventricles to reduce pressure (CHF, LVH/RVH). It causes natriuresis and diuresis. Allows you to stage CHF (stages 3 & 4) by NYHA classes
CHF symptoms & Best Test
Dyspnea on exertion, Orthopnea, Fatigue, Edema, Paroxysmal nocturnal dyspnea (PUFFY SWOLLEN SNORER) BNP test
BNP values & limitations
Normal: <100, up to 300 w/ age, female
CHF can exceed 1000
IF positive, ECHO
Lipid Panel Components & Requirements
Total Cholesterol fx, lab use, values
Used to make steroids, membranes, vitamin D, bile acids. Tests for CHD & risk of Atherosclerosis
Triglycerides fx, lab use, values
Carried BY lipoproteins FROM gut TO adipocytes. Tests for risk of Atherosclerosis.
Plain scary: >500
HDL fx, lab use, values
Lipoprotein that transports cholesterol FROM tissues TO liver. HIGH HDL --> LOW CHD risk (inverse risk)
Near-zero risk: >75
Acceptable female: >50
Acceptable male: >40
2X CHD risk: <25
LDL fx, test uses and values
lipoprotein that carries cholesterol TO tissues FROM the liver. LDL levels are directly proportional to atherosclerosis and CHD risk
DM and CHD: <70
At risk for CHD: <100
The FIVE CHD RISK factors
Smoking, HTN, Low HDL, FamHx premature CHD in male <55 or female <65; Age: Male >45, Female >55
ApA1:ApB -->HDL lipoproteins : LDL lipoproteins
More sensitivity & specificity than HDL : LDL ratio
Cardio-C Reactive Protein; Acute phase inflammation marker. Coronary artery endothelial inflammation raises c-CRP