Lab Tests

Question 1

reference intervals

Answer 1

“normal”

derived by screening many healthy individuals

encompasses central 95% of normal population

Question 2

some distributions are not gaussian. examples?

Answer 2

things like cholesterol, LDL, tryglyceride, and HDL

Question 3

how do we transform non gaussian data?

Answer 3

nonparametric method

.025 * (n+1)
.975 * (n+1)

Question 4

troponin

Answer 4

biomarker for myocyte damage

anything above 99th percentile represents myocyte damage

Question 5

two ways to determine reference intervals

Answer 5

established via parametric/non-parametric means

OR

via decision limits and treatment guidelines (A1C)

Question 6

critical tests

Answer 6

any test that always require rapid communication to the ordering provider, whether the results are normal or not

Question 7

critical result

Answer 7

any lab finding that requires a rapid communication of results

results represent a potentilly life threatening action

Question 8

3 phases of laboratory testing

Answer 8

pre- deciding to test, sample collection, processing, transport etc.

pre causes most errors

analytical- receiving specimen, analysis, result

post- physician acknowledge result, implementation of treatment

Question 9

preanalytic errors

Answer 9

order entry- similar names, duplicate order, trnascription

patient prep

needle size

tube selection

tourniquet

improper storage, delayed processing

Question 10

postanalytic errors

Answer 10

transcription error

calculation errors

errors in result inrepretation

Question 11

analytic variation

Answer 11

differences d/t assay imprecision

bias

Question 12

spectral interference

Answer 12

many assays incorporate a spectrophotometer

hemolysis produces spectral interference

Question 13

pseudohyponatremia

Answer 13

specific interference for indirect ion-selective electrodes

essentially a dilutional error produced by high concentrations of proteins and lipids (ie if serum is less than 93% water)

Question 14

hook effect

Answer 14

found in ELISAs w/ markers w/ high levels in a pathological state

results in a false low/negative

Question 15

loss of self tolerance

Answer 15

pts develop autoAbs to proteins, causing them to stick around and read as artifically high when there is no disease

Question 16

HAMA

Answer 16

occurs in sandwhich assays when pt has Abs that recognize the Abs used in the assay