Introduction to Laboratory Testing Flashcards
use of diagnostic testing?
take info from H and P to come up with differential diagnosis
-testing will help guide the diagnostic work up and support your differential dx
3 main uses of diagnostic testing?
diagnosis, screening, patient management
how to decide what to order?
- H and P and DDx
- potential benefits vs. costs and disadvantages
- don’t order a test if you don’t know what to do with it**
how many diagnostic tests?
hundreds for various reasons
reference range?
use the range of the lab doing the testing
- for 95% of the populations
- 5% population varies outside this range
types of common tests?
gross pathology, cellular pathology, function, special tests
examples of gross pathology diagnostic testing?
scopes
x-rays
IVP
spinal myelogram
scope
visualize organ systems internally
x-rays
radiation to detect changes in density of tissues, bone and viscera
IVP
intravenous pyelogram
-view of kidneys, ureters and bladder, usually detect kidney stones, tumors and other blockages in system
**kidney stones
spinal myelogram
look for spatial changes in spinal canal
types of myelograms?
IVP and spinal myelogram
more advanced x-ray technology?
CT scan - x-ray of body tissues that produces slices (cross sections) of an area of the body
-evaluate large areas
CT scan
with or without contrast**
without contrast- spiral CT of kidneys
with contrast- IV or PO (oral) used to highlight bleeds, small structure in brain, kidneys, spine, and liver
contrast used in CT scan?
iodine, barium, gastrografin
radioactive agent
-make sure patient has good kidney function**
MRI
no radiaton**
uses magnetic fields and pulses to give cross sections
can identify masses, tears, bleeding, tissue damage from infection and injury anywhere in body
can be done with or without contrast
cellular pathology?
biopsy, puncture, FOBT, serum studies, urinalysis, cultures and sensitivies
puncture?
removal of fluid from area for analysis
fecal occult blood test?
blood in fecal matter
serum studies?
routine exam of blood
urinalysis
exam of urine for cells, tiny structues, bacteria, and chemicals
cultures and sensitivities
C and S
-growth of an organism from body fluid to identify an organism causing pathology and to identify what is best course of therapy
function diagnostic testing?
ultrasound and doppler studies
electrograms
angiograms/venograms
ultrasound
sound waves to detect movement and function of organs
**no radiation
doppler studies
sound waves and sonar to detect abnormal blood flow
electrogram
test for electrical activity of tissues
EKG or ECG
-electric activity of heart
also nerve conduction studies
angiograms/venograms
use dye to detect blockages in arteries and veins
**these are x-ray pictures
blood test
analysis on blood sample via venipuncture
-determine physiological and biochemical states
disease, mineral content, drug effectiveness, organ function
also used in drug tests
CBC
complete blood count
-cellular components of blood (RBC, WBC, platelets)
values usually correspond to one of many anemias affecting patient
-also correspond with infections and malignancies
shorthand of CBC?
left WBC
right platelet
top hemoblobin
bottom hematocrit
normal ration of hemoglobin to hematocrit
1/3
total erythrocyte range?
4.7e6 - 6.1e6
hemoglobin range
female - 12/16 g/dL
male - 14-18 g/dL
hematocrit range
female 37-47%
male 40-54%
hematocrit increase?
high altitude, smoker, tumors
hematocrit decrease?
anemia (iron, folate, B12), acute/chronic blood loss, hemolysis
hemoglobin increase?
dehydration, burns, vomiting
hemoglobin decrease?
all anemias, hypothyroidism, B12 and folate deficiency, chronic disease
normal range for WBCs?
4,800 - 10,800 cells/microliter
CBC and WBCs?
can be ordered with or without differential**
alteration of WBC levels?
infection, inflammation, hemotologic malignancies, leukemias, lymphoma, steroid use, aneimas, drugs, and sepsis
left shift of neutrophils?
predominance of immature cells
-infection, toxemia, hemorrhage
right shift of neutrophils?
predominance of mature cells
-liver disease, anemias, iron deficiency
most dominant WBC?
neutrophils (46-80%)
lymphocytes
increased in viral disease
-also acute and chronic lymphocytic leukemias
monocytes
increased in bacterial and protozial infection
-also infections mono
eosinophils
increased in allergy and parasites
basophils
increased in chronic myeloid leukemia
increased in platelets?
after stress
-trauma and surgical, childbirth, fractures, exercise
prothrombin time
assess coagulation pathway
-common for patients on anti-coagulants
normal 11-15 seconds
INR - international normalized ratio
normal platelet count?
150,000 - 450,000 microliters
warfarin/coumadin?
use PT/INR to asses efficacy of drug
-reading should be 2-3x normal
peripheral blood smear?
stain and scopes viewer can evaluate the size shape and content of blood cells
things seen in peripheral blood smear?
macrocytes, schistocytes (helmet cells), howell jolly bodies
plasmodium
parasite in malaria
microcytic hypochromic
iron deficiency anemia
lymphoblasts
elevated levels can indicate lymphoma
basophilic stippling
remnants of DNA in RBCs
-lead poisoning or thalassemia
diagnostic by PBS?
plasmodium, microcytic hypochromic, lymphoblasts, basophilic stippling
basic metabolic panel
non-cellular elements of blood
-sodium and chloride
sodium
predominant cation in ECF
creates most osmotic pressure, essential for proper neuron and muscle activity
chloride
predominant anion in ECF
affects osmotic pressure of serum
tends to follow sodium
increased sodium?
hypernatremia - excessive water loss or sodium injection, loss of ICF fluid characterized by extreme thirst and agitation
decreased sodium?
hyponatremia - excessive sweating
- also caused by diarrhea or vomiting
- causes dizziness, confusion, weakness, low BP and shock
increased chloride?
diarrhea
decreased chloride?
vomiting, DM with ketoacidosis
bicarbonate levels?
major buffer of blood when protons are produced by metabolism
used to transport CO2
excretion controlled by kidneys
increased bicarbonate
metabolic alkalosis from respiratory acidosis
decreased bicarbonate
metabolic acisosis from respiratory alkalosis
potassium
predominant cation in cellular fluid
-changes in serum concentration greatly affects nerve excitation, muscle contraction, myocardial potential
increased potassium
hyperkalemia
-renal failure of addisons disease causing weakness, abnormal sensations, cardiac arrhythmias with possible arrest, also in hemolysis of specimin, thrombocytosis, dehydration, massive tissue damage
decreased potassium
hypokalemia
-in diuretics, vomiting
increased glucose levels
hyperglycemia in DM
decreased glucose levels
hypoglycemia in pancreatic disorders
blood urea nitrogen
increased in renal failure or GI bleed
creatinine
increased in renal failure, loss of muscle mass
normal BUN:Cr ratio
10-20:1
-used to identify source of dysfunction when values are not in the normal range
prerenal?
greater than 20:1
BUN reabsorption increased, dehydration suspected
normal or postrenal
10-20:1
normal range and also postrenal disease
intrarenal
less than 10:1
renal damage causes reduced reabsorption of BUN
glucose level measurement?
fasting important**
when to use kidney studies?
kidney function OR contrast studies
direct vs. indirect bilirubin?
direct is conjugated
indirect is unconjugated
bilirubin
from breakdown of heme
-insoluble in water, bound to plasma proteins until conjugated with glucuronic acid in liver
total bilirubin levels?
less than 0.3 - 1 mg/dL
increased in hepatic damage
direct bilirubin?
conjugated
increased in biliary obstruction, dubin johnson, rotor
indirect bilirubin?
unconjugated
hemolysis, gilbert, crigler-najjar
hemoglobin A1C
accurate measure of average blood sugar over average live of circulating erythrocyte
-approx 6 weeks
now used to diagnose and monitor diabetes control
c-reactive protein
acute phase reactant with a short half life
-rises rapidly within 4-6 hours of the onset of inflammation or tissue injury
declines relatively rapidly with resolution, correlates with older very non-specific test called sedimentation rate (ESR)
cholesterol
insoluble in water
- carried by lipoproteins
- ingested and synthesized by liver
increased cholesterol?
hypercholesterolemia
-congenital, hypothyroidism, DM, fatty diet and obesity
LDL
high levels - accelerated artherogenesis
HDL
high levels protective
triglycerides
absorbed in blood after fatty meal
- broken down and stored as adipose
- major form of energy at cellular level
- increased levels also associated with accelerated artherogenesis
liver profile and liver disease?
all enzymes are increased with liver disease
-cirrhosis
enzymes in liver profile?
alanine aminotransferase (ALT) aspartate aminotransferase (AST) gamma-glutamyl transferase (GGT)
alcoholic hepatitis?
AST > ALT
viral hepatitis?
ALT > AST
thyroid hormone
essential in regulation of metabolism
normal urinalysis?
normal is clear/yellow slightly acidic negative for: -bacteria, bilirubin, blood, ketone, glucose, protein, intrite, leukocyte esterase (if normal) trace sediments normal: -RBC, WBC
abnormal urinalysis?
- cloudy, foamy, dark yellow/green, red to black, purple to brown
- increased acidity
cloudy urinalysis?
pyuria, blood, mucus, bilirubin
foamy urine?
proteinuria, bile salts
dark yellow or green urine?
bile or bilirubin
red to black urine?
RBCs, hemoglobin, myoglobin
purple to brown urine?
specimens standing in sunlight from porphyrins
increased urine acidity?
infections (proteus), systemic alkalosis, renal tubular acidosis
increased specific gravity of urine?
volume depletion
decreased specific gravity of urine?
infection, compulsive water drinking
bilirubin in urine?
primarily conjugated
-obstructive biliary tract disease, liver disease
blood in urine?
stones, tumors, coagulopathy, infection, menses (contamination)
dipstick positive for blood?
no red cells present
-may be free Hg from trauma or a transfusion reaction or lysis of RBCs or there is myoglobin present because of crush injury, burn, or tissue ischemia
glucose in urine?
positive in DM
-especially with serum glucose over 200mg/dL
also positive in pancreatitis
ketones in urine?
positive in starvation/fasting, diabetic acidosis, vomiting, diarrhea
protein in urine?
mostly albumin
-positive in pyelonephritis, nephrotic syndrome
leukocyte esterase in urine
with nitrite test, predictive value for UTI of 74% if both tests positive
nitrite test in urine?
positive in infection
