Laboratory Administration

Question 1

Percentages at 1,2,3 SD if Gaussian

Answer 1

1sd=68%
2sd=95.5%
3sd=99.7%

Question 2

SD=

Answer 2

average distance of a value from the mean

Question 3

Mode

Answer 3

most frequent value

Question 4

Coefficient of variation

Answer 4

describes the sd as % of the mean at a particular analyte concentration

Question 5

CV=

Answer 5

SD/meanx100

Question 6

Clinical sensitivity

Answer 6

positivity in presence of disease

Question 7

Sensitivity=

Answer 7

TP/(TP+FN)

Question 8

Specificity=

Answer 8

TN(TN+FP)

Question 9

PPV definition

Answer 9

percent of + results that actually indicate dz

Question 10

PPV=

Answer 10

TP/all+

Question 11

NPV=

Answer 11

TN/all-

Question 12

when dz prevalence is low, PPV ___, NPV ____

Answer 12

PPV decreases

NPV increases

Question 13

Punnett square

Answer 13

x=dz, y = test result,
top left = True positive
bottom right = true negative

Question 14

Relative risk definition

Answer 14

risk of an outcome “Y” in the presence of condition “X” as compared to the population

Question 15

RR=

Answer 15

(#with X who develop Y/#with X) / (#in pop with Y/# in pop)

Question 16

ordinal scale

Answer 16

gives a number with an assigned value (ex. urine protein 1+)

Question 17

ROC curve

Answer 17

X-axis = 1-specificity (1-false+)
Y-axis = sensitivity (true+)

Question 18

ROC curve provides

Answer 18

view of whole spectrum of sensitivities and specificities at different cut off values

Question 19

Most accurate point on ROC curve

Answer 19

closest to upper left corner

Question 20

Wesgard rules

Answer 20

1:3s = 1 value 3sd above mean
2:2s = 2 in row 2sd on same side
R:4s = two values >4sd from each other
4:1s = 4 in a row 1sd on same side
10:mean = 10 on same side of mean

Question 21

Westguard rules addressing drifts and shifts

Answer 21

(systematic errors)

2: 2s
4: 1s
10: mean

Question 22

agency approving proficiency testing

Answer 22

Dept of Health and Human Services

Question 23

Satisfactory proficiency testing

Answer 23

acceptable results in >4/5

3x/yr x 5 samples

Question 24

random variability increases with

Answer 24

increasing [analyte]

Question 25

analytical sensitivity

Answer 25

lowest analyte concentration detectable

Question 26

analytical sensitivity calculation

Answer 26

mean + 3sd (of lots of runs with no analyte)

Question 27

interferences are responsible for a ____ bias

Answer 27

constant

Question 28

solvent exclusion effect

Answer 28

indirect ISE

lipemia, paraprotein

Question 29

when sitting, concentration of ____ goes ___ by __%

Answer 29

proteins, cells, things bound to proteins
up
5-15%

Question 30

order of collection

Answer 30

Culture
Red
Blue
Green
Purple
Gray

Question 31

Anion gap

Answer 31

Na- (Cl+HCO3)

Question 32

osmolal gap

Answer 32

measured - (2Na + Glu/18 + BUN/2.8)

Question 33

Friedewald equation

Answer 33

LDL=Tchol-HDL-TG/5

Question 34

FENA=

Answer 34

(Urine Na x Plasma creat)/(Urine creat x Plasma Na)

Question 35

Correction of anion gap for hypoalbuminemia

Answer 35

+2.5(4-albumin)