Basic Laboratory Testing Flashcards
what is the definition of sensitivity?
the measure of the tests ability to detect persons who have a disease or condition (true positive)
What is the definition of specificity?
the measure of how well the test excludes the possibility of of a particular disease (true negatives)
between sensitive and specificity, which is attempted to be maximized by laboratory testing.
maximize specificity
what is hemolysis?
rupture of RBC, classified as slight, moderate, or severe, based on amount of hemoglohin present in serum.
what is Lipemia?
presence of high concentration of lipids in serum.
what are the two origins of lipemia?
- due to postprandial hyperlipidemic following a high-fat meal
- genetic make-up (uncommon)
what is glycolysis?
the breakdown of glucose.
what tests provide a more reliable estimate of average glucose levels?
Fructosamine and HB A1C.
what is
- mg/dL
- ug/ml
- IU/L
- miligram per 100ml sample
- microgram/milliliter
- enzyme activity, International units/liter.
Most of the world has switched to “S.I” units. Name 2 examples.
U/L and mmol/L
what is Venipuncture?
blood drawn from a vein, obtained by PM, phlebotomist, nurses, or doctors.
what is dried blood spot?
the side of the finger is puncures with a lancet and as droplets of blood form, the droplets are transferred to a small piece of blotting paper. used fo HIV
saliva and urine?
lower policy amounts, and certin risk assessments. Saliva detexts HIV, cotinine, cocaine.
what tests can be collected form an AOR?
saliva and urine.
what is the typical transport time for blood? (seperation of serum from CBC)
2 days. `
what is the standard deviation?
it refers to the normal variation in personal biologic set point and reflects differences in the genetic background of people. the reference range includes 95% of the population.
on what basis is relative risk based on?
its based on a comparison to the standard mortality of he same age applicant.
how is pricing for insurance products determined?
based on average mortality based on age. increased risk indicates a higher risk of death compared to the STD risj.
what is evaluated through a basic urine sample?
drugs, nicotine, creatining, protein, glucose and blood cells, antibodies.
what is evaluated through a saliva sample?
HIV, cotinine, and cocaine.
what is a reflex test, and when would you order one?
reflexive testing is run following abnormal levels in the BW. ^ ALT > hepatitis screnning is run, an alcohol screening is run for elevated HDL and liver enzymes.
how long is a urine sample typically held?
4-5 weeks. ,
what is the best measure of renal filtration function in a urinalysis
GFR- glomerular filtration rate, we can be measured by excretion of an injected dye or radionucleotide. eGFR is typically used in u/w process.
how is eGFR calculated?
using age, sex, and the serum creatinine measurement from the blood
what is creatinine, and what is the average dispenced amount by people?
the breakdown product of muscle metabolism. average 1g per day.
why is creatinine used to adjust for variation in urine samples?
it is a steadied pace, and typically urine concentration can vary based on fluid intake, but using creatinine as a based of [ ] for comparison allows for more consistent results. `
what is the best method to determine concentration changes?
by using the rations such as protein/creatinine, and albumin/creatinine.
some people will try to adjust their urine levels to read lower/ negative readings. what is the creatinine minimum we will accept, before asking for a new sample/investigate (women vx men)
women 9mg/dL
men 11mg/dL
what amount of proteinuria is associated with excess mortality
150mg/day
what form of protein is not detected by urinalysis?
globulin
A sample positive for proteinuria can become negative when what calculation is applied, and why?
urine is more concentrated in the morning than at night, so we apply the creatitine calculation.
what disease tipicallt causes an excess of albuminuria?
glomerular disease, followed by kidney disdease, damage to kidney from HTN, and tubular proteinuria.
Which disease has a great increase of mortality when albuminuria is present?
diabetes- d/t cardiovascular mortality
albumin makes up approx. one half of urinary protein excretion. What diease, causes that percentage to increase
kidney disease. early stages, cause minor changes, when the level is between 30-300, the condition is microalbuminuria, when its above that its called albuminuria.
IF urine test +ve for glucose what test is reflexed on the BW?
A1C.
when should a blood sample be collected, in terms of amount of glucose in the urine?
when its greater than 0.05g/dL.
what is leukocyte esterase, and hemoglobin?
an ezyme present in WBC, a protein present in RBC.
If a urine test is +ve for Leukocyte esterase
examined by flow cytometery (sophisticated automated microscope) to count RBC and WBC.
what are some possible explinations to why there is hematuria?
infection, glomerulonephritis, kidney-ca, and UTI, disease of metabolism, or possible collection of adftifact in menstruating females.
what is the magic number of RBC to be considered a risk?
> 9
what level of hematuria appears to be associated with increased risk for females > 60 years old or less?
none
what are urine casts?
aggregates of proteins or red or white cells. theyre formed from the inside wall of the kidney tubules.
in 2010, what was the leading cause of accidental death in young females?
opiate overdose.
many drug samplings are the same, use cocaine as an example. How is cocaine usage determined?
when sample is +Ve for metabolits, the presence is varified by gas chromatography mass spectroscopy (GCMS) or by LCMSMS,. each drug produces a unique finger print.
Every insurance company tests for cocaine, what are some other common tests run by insurance companies?
marijuana, and amphetamine. The following are just common drugs of abuse:
opiates, PCP, barbituates,
what is the half-life of nicotine (through the blood system)
one to two hours, but a smoker will typically test positive for cotinine 1-3 days after last sue.
what is cotinine? How long is it in the body?
it is the metabolite of nicotine, converted by the liver. The clearance rate is 16-18 hours. Teh specificity of this test is 99.0% accurate.
Cotinine, is detected in 9-29% of insurance samples. Approx. How many of the cotinine possitive samples are applying as non-tobacco users?
1/3-1/2. When confronted with a denial of use, the original sample can be tested with GCMS or LCMSMS, to confirm.
can a cotinine test differentiate between cigar, or nicotine substitutes from cigarrette smoking?
NO
does UTI affect the morality of a person?
no, the exception to this could be chronic infection of the kidney or bladder
what 3 tests are typically run on saliva?
HIV, cotinine, and cocaine. the normal range for saliva test results is different than for urine and blood.
is the preverlance of HIV, cocaine, and contine higher in the savlia-tested population than in any other proposed insurance group?
yes
how long does it take for infected individuales to produce antibodies (HIV) ?
4-8 weeks. thats why all initially reactive samples are tested in duplicate to verify the result.
what test is prefroemd, when repeating HIV +ve sampled?
western blot. This confirms +ve diagnosis, although with increasing sensitivity of the initial antibody test, this test may be replaced by HIV_RNA.
in most insurances cases, a -ve test will be reported to the UW, but a +ve would be reported to the MD. True or false?
trueeeee
what is hepatitis?
inflammation of the liver.
What is acute hepatitis?
caused by infection of hep virus, (A,-E) or by viral infection (mononucleosis), non-viral infection (drugs, alcohol, metal poisoning, toxins, acute obstruction of blood vessles that drain into the liver).
what is the marker for acute hepatitis?
Liver enzyme elevated from 3-10x normal, and will return to wnl, in 6 months.
What is chronic hepatitis?
liver enzyme elevations lasting longer than six months. caused by non-alcoholic fatty liver, anti-inflammatory drugs, hepatitis c or b, and alcohol.
Chronic inflammation of the liver increases the risk for what disease?
fibrosis, cirrhosis, and hepatocellular carcinoma.
how is HBV detected?
presence of surface antiagen. The new methododlogy for HBV is to detect the viral DNA.
why is hep b so dangerous?
becomes chronic in some cases (very few), but can increase to 25-90% if the infection is passes from mother to child or was acquired during childhood.
What is the leading cause of liver failure and transplantation and why?
HCV, it becomes chronic in 70-85 % of infected individuals. the anitbody is detectable in 6-12 weeks.
what is the only energy source that the brain uses in terms of sugars?
glucose
high fasting glucose values are indicative of what kind of disease?
GIT or diabetes.
glucose continues to be metabolized by the blood, even after the sample has been collected
what what glucose level do we typically reflex the sample for A1C?
> 110 mg/dL
what does fructosamine meaures?
the amount of glucose that becomes attached to serium proteins and is rough by inexpensive indicator.
what is the gold standard test for evaluating a diabetic risk?
HB A1C
AKA: glycohemoglobin, glycated hemoglobin, glycosylated hemoglocin.
A measure of the amount of glycated hemoglobin is a measure of the average glucose concentration over the prior 6 month period. True or false?
false- its 120 days, becausr RBC have a half-life of 120 days. (hemoglobin binds loosely to the N terminal amino acid of hemoglobin)
what are the levels of A1C in relation to diabetic risk?
6.0% or higher, is abnormal
6.5% is diagnostic of diabetes,
(the higher the %, the more the risk)
what test is typically run, with a high A1C in the blood work?
a urine test with a reflect microalbumin test. renal disease is a comorbidity of diabetes.
what is synthesized by the liver? what does the liver produce?
cholesterol, albumin, glucose, transferrin, and the clotting factors.
liver produces bile
what are the four serum enzymes used to measure a livers well-being?
AST, ALT, CCT, AP.
what is a transaminase?
ALT and AST, they are usually the elevated ones during hepatic disease, AST can be associate with alcohol damage and fibroisis.
can ALT and AST (less comon) be elevated d/t a fatty liver, and non-alcoholic steatophepatis (NASH), both associated with obesity?
Yes
elevations of GGT and AP are associated with biliary obstruction or inflammation. true or false?
True
what is typically the cause when only GGT is elevated?
drugs, or alcohol.
Theres a strong connection between GGT ^ and cardiovascular risks.
what are some indirect markers of excess alcohol use? What are secondary tests used?
^ HDL, ^ LFTs (specially GGT) and low blood urea nitrogen.
prefeorm a CDT or HAA. CDT have high correlation with chronic alcohol abuse.
what are the 3 physiological lipid particles of cholesterol?
HDL, LDL, and VLDL
which synthesized lipid particle transports cholesterol from the liver to the peripheral tissue?
LDL
which ^ lipid is associated with greater cardiovascular risk?
LDL
which lipid particle transport cholesterol from the peripheral tissue back to the liver?
HDL
low HDL is a risk factor for the development of which disease?
Coronary disease
do male or females tend to have a higher HDL?
females
what is apolipoproteins?
ApoE4 is a potential protein marker for risk of Alzheimers.- not currently used in insurance- but can find in APS.
what are symptoms are insulin resistant syndrome?
slight elevations of cholesterol, trigs, glucose, and BP, with low HDL in the presence of obesity. »_space; if more than 5 factors present, theres an increased cardiovascular risk.
what organ is the primary site for the synthesis of proBNP hormone, and what organ is the site of its biological action?
the heart, and the kidneys
why is proBNP produced by the body?
in response to heart failure.
what is NT-proBNP?
its a more stable, and a better indicator or heart failer, its an independent predictor of mortality risk. (tends to be higher in females)
what is the serum concentration on creatinine?
the balance between the rate of creatinine production and the rate of elimination by the kidneys. > meaures renal filtration and urine formation.
in what sex is creatinine more elevated?
its related to muscle mass, so young men or people with high meat diets. As people age so does muscle mass, creatinine is relatively stable in life.
what is BUN
by-product from the breakdown of protein. the serum [ ] is directly proportional to its rate of production minues the rate of renal removal.
when is BUN low?
with low protein diets, or sever liver disease
what is cystatin C?
low molecular weight protein present in nucleated cells, - its testing is very expensive, and therefore usually used as a reflex for samples with high serum creatinine values.
what is GFR measuring?
the volume of blood that the kidney filters per minute. is usually estimate in our calculations, the lower the value the worst the disease. It can also be calculated using cystatin C.
when does albumin decrease? when does albumin increase?
decrease: starvation and cirrhosis.
increase: dehydration.
what is bilirubin?
the breakdown product of the heme in hemoglobin. Heme is converted to bilirubin in the liver
what is a concern with ^ bilirubin?
d/t liver disease or obstruction. If its isolated finding usually d/t genetic defect.
what is globulin?
the fraction of blood that includes the immunoglobulines, or antibodies. high levels indicate acute or chronic infection, myeloma or recently cleared infection.
how is globulin calculated?
subtracting the albumin from the total protein.
what is myeloma?
cancer of the plasma cells. identified by the antibodies monoclonal and polyclonal.
what is uric acid?
metabolite product from the oxidation of purine bases. high values associated with renal disease, hypertension, gout and use of thiazide diuretics.
what is included in a CBC “differential”?
red cell count, white cell count (lymphocytes, macrophages, and granulocytes), platelet count, hematocrit, and hemoglobin in g/dL.
why is it important for the uw to note the absolute count on a differential ?
relative number of cells present can be normal, white the absolute count is abnormal. This occurs in anemia and hematological cancers.
What is PSA? when are its levels increase?
a protein produced by the prostate. Increased in BPH, and in inflammation (prostatitis).
what are the two forms of PSA in serum?
free and bound. the total SPA is the sum of the two.
What is carcinoembryonic antigen (CEA) ?
is produced by many solid tumors.
when would you run a CEA test?
after cancer tx, if their dx was associated with CEA elevations.
why do we not use CEA typically in insurance screening?
high number of false positives, and if its very high, no cure of any tumor found is generally possible.
what is BRCA?
chest x-ray marker associated with increased risk of development of breast and ovarian cancer.
what is Ca-19-9?
marker for gastrointestinal cancer
what is alpha fetoprotein (AFP)?
marker for liver and germ cell cancer
what is beta chorionic gonadotropin (HCG)?
marker for germ cell cancer
what is a benefit of genetic testing?
clinically determine course of tx and the probability of outcomes for various cancers. None is used in u/w currently.
why is there no set/ standard expected or reference range values?
- individual insurance companies have different cut offs.
2. individual labratory normal ranges vary.
elevations in GGT and AP are associate with pancreatitis or biliary obstruction?
biliary obstruction
