Intro terms and lab tests Flashcards
what term measures the validity of tests?
specificity
what term is disease oriented and identifies those with the disease correctly?
sensitivity
If a test is highly sensitive what does is minimize?
false negatives
SNOUT (Sensitive test with Negative results rules OUT disease)
true positives/ true positives + false negatives =??
sensitivity
What term is healthy oriented and correctly identifies those without disease?
specificity
If specificity is high, what does it minimize?
false positives (SPIN) Specific test with Positive result rules IN disease
true negatives/ true negatives + false positives=??
specificity
What is the normal range or reference range?
the test results from healthy patient population that distribute into a bell curve
central 95% is the tests normal range
*healthy individuals may fall outside the range and thats their own normal
What test would be helpful in diagnosing UTI, kidney stones, malignancy and identifying systemic disease?
Urinalysis
Physical exam part of urinalysis; what would these characteristics determine?
cloudy, foul smell, sweet smell, red color, yellow color, brown color
cloudy-bacteria, blood, crystals
foul smell-infection, sweet smell-ketones/diabetes
red-hematuria, kidney stones, UTI, bladder cancer
yellow-dehydration
brown-gomerulonephritis
specific gravity of chemical part of urinalysis shows what
elevated with volume depletion
decreased with excessive fluid
pH of urinalysis (4.6-8); if abnormal what does that indicate?
increased with vomiting, UTI, kidney disease
decreased with aspirin overdose, starvation, alcohol, high protein diet
should protein be in the urine?
no– too large to pass through glomerulus, indicates glomerulonephritis, diabetes complication
glucose in the urine indicates what?
uncontrolled diabetes, burns, pancreatitis, corticosteroid use, kushings disease
ketones in the urine indicates what?
ketones are produced from the breakdown of fat
starvation, alcoholism, diabetic ketoacidosis
bilirubin in the urine indicates what?
by-product of hemolysis
biliary obstruction and liver injury
leukocyte esterase (detects enzymes released by WBCs) in the urine indicates what
UTI
urobilinogen (bilirubin can interact with bacteria in the gut to produce it) in the urine is associated with what?
hemolysis and hepatocellular disease
nitrites in the urine
only some bacteria convert nitrate to nitrite
infection
upon microscopic exam of urinalysis what is the normal range under high power:
WBC
RBC
WBC: 0-5
RBC: 0-3
red blood casts indicates what?
glomerulonephritis
white blood casts indicates what?
pyelonephritis
test that is sensitive for liver injury (in addition to aspartate aminotransferase/AST)
alanine aminotransferase (ALT)
what liver profile test would be elevated with bile duct obstruction?
alkaline phosphatase
what is elevated with liver injury or biliary obstruction and parallels alkaline phosphatase?
GGT (gamma glutamyl transpeptidase)
what is unconjugated bilirubin elevated with and what is conjugated bilirubin elevated with?
unconjugated(bilirubin bound to albumin, not water soluble)-hemolysis
conjugated (water soluable)- bile duct obstruction
what plasma protein is a marker of liver function?
albumin
what measures the time required for coagulation to occur, a measure of liver function and the coagulation proteins produced by the liver?
prothromin time
what are indications for ordering coagulation studies
unexplained bleeding disorder/excessive bruising
pregnancy loss
patients on heparin or coumadin
what coagulation study measures the extrinsic pathway and deals with INR in monitoring patients on coumadin?
PT (prothrombin time)
what coagulation study measures the intrinsic pathway and is used to monitor heparin therapy?
aPTT (partial thromboplastin time)
what do prolonged coagulation studies indicate?
patients on coumadin or heparin
liver injury–cirrhosis
vitamin K deficiency
increased levels of amylase and lipase may be associated with what?
pancreatitis, biliary obstruction, pancreatic carcinoma
is amylase or lipase more specific for pancreatic inflammation
lipase
electrolyte tests measure what?
overall fluid status, acid/base status
what electrolyte is the major extracellular cation, involved in blood and body fluid homeostasis, conduction of impulses and regulated by osmoreceptors in the hypothalamus?
Sodium
dehydration, vomiting and diarrhea, and endocrine problems would cause sodium levels to increase or decrease?
increase (>145)
overhydration and cushings disease would cause sodium levels to do what?
decrease (
the major intracellular cation and involved in impulse conduction through membrane depolarization
potassium
cell injury, kidney failure and addisons disease do what to potassium
elevate (>5)
*arrhythmia’s
malnutrition, vomiting and diarrhea, diuretics do what to potassium?
decrease (
effect on chloride levels
dehydration and overactive parathyroid glands:
vomiting/ loss of gastric acid:
elevated (>107)
decrease (
use of antacids and kidney disease does what to magnesium
elevate
inadequate absorption and diuretics does what to magnesium
decrease
calcium
-half is protein bound, half is ionized
only ionized is metabolically active
important in what?
muscle contraction, cardiac function, nerve impulse, blood clotting
hyperparathyroid, cancer, excessive vitamin D
-does what to calcium levels?
elevate
hypoparathyroid, deficient protein, vitamin D deficiency
-does what to calcium levels?
decrease
effect of insulin and glucagon on blood glucose
insulin–decrease
glucagon–increase
what test measures the average blood glucose over the past 2-3 months
hemoglobin A1C (normal
what does BUN measure
blood urea nitrogen
protein breakdown–waste is produced as urea in the liver–urea filtered by kidneys, excreted in urine
impaired kidney function, decreased protein catabolism, dehydration
–elevated or decreased BUN?
elevated
liver failure, malnutrition, endocrine disorders
–elevated or decreased BUN
decreased
production of ___ is constant and correlates with muscle mass, excreted by kidneys, assess renal function
creatinine
what kidney test is more specific and sensitive than BUN in kidney disease
creatinine
impaired renal function, large muscle mass–
decreased muscle mass, liver disease–
which is elevated creatinine and which is decreased
elevated creatinine–impaired renal function
decrease– decrease muscle mass and liver disease
levels of ___ are increased with: excessive cell breakdown of nucleonic acids(gout), destruction of cells (leukemia), inability to excrete ___ (renal failure)
uric acid
whats the most sensitive test for screening thyroid disorders
TSH
decreased TSH, increased T4 and T3 is what
hyperthyroidism
elevated TSH, decreased T4 and T3 is what
hypothyroidism
what is the gold standard for streptococcal pharyngitis
throat culture
Misc labs:
sedimentation rate–
screen for venous thrombosis–
increased with CHF–
marker of inflammation
D dimer
brain natriuretic peptide (BNP)
