Lab Medicine

Front 1

Likelihood that a patient with disease will have a + test result

Back 1

Sensitivity

Front 2

Formula for Sensitivity

Back 2

TP/(TP+FN)

Front 3

What tests are great for screening?

Back 3

Tests with 100% sensitivity
Excludes disease when the test is negative, because a negative test must be a TN not a FN.

Front 4

What does does a positive test tell you if sensitivity is 80%?

Back 4

It does NOT distinguish a TP from a FP. FP is not in the formula. However a positive test includes the possibility that it is a TP.

Front 5

Likelihood that a patient without disease will have a negative test result.

Back 5

Specificity

Front 6

Formula for Specificity

Back 6

TN/(TN + FP)

Front 7

Which test is used for confirming disease?

Back 7

Test with 100% specificity, when positive confirms disease. Must be a TP rather than a FP.

Front 8

Likelihood that a negative result in a patient is a TN rather than a FN.

Back 8

Negative Predictive Value

Front 9

Formula for PV-

Back 9

TN/(TN+FN)

Front 10

If sensitivity is 100% then PV- is always 100%

Back 10

True

Front 11

Serum ANA = antinuclear antibody for systemic lupus erythematosus

Back 11

Sensitivity 100%
Specificity 80%
Use for Screening

Front 12

anti-Smith antibody

Back 12

Specificity 100% used to confirm SLE

Front 13

A test has a sensitivity of 100% and a specificity of 80%. If a patient has a positive test result, you conclude

Back 13

It could be a TP or a FP because of the Specificity 80%.

Front 14

Likelihood that a positive result in a patient is a TP rather than a FP.

Back 14

PV+
Positive Predictive Value
TP/(TP + FP)

Front 15

Specificity 100% then PV+ is?

Back 15

Always 100%

Front 16

A test has a sensitivity of 30% and a specificity of 100%. If a patient has a positive test result, it must be a

Back 16

TP

Front 17

Total # of people with disease in a population being studied

Back 17

Prevalence
(TP + FN)People with disease
/ (TP + FN + TN +FP) total population

Front 18

Formula for Prevalence

Back 18

P = Incidence x Duration

Front 19

If prev increase what happens to predictive values?

Back 19

PV+ increases, TP more likely than a FP
PV- decreases, FN more likely than a TN

Front 20

If treatment for a certain type of leukemia lengthens the survival period but does not lead to its cure, what happens to prevalence of that particular type of leukemia?

Back 20

Increases, also PV+ increases and PV - decreases

Front 21

The ability of a measurement to be consistently reproduced

Back 21

Precision

Front 22

Variation from the mean of the test

Back 22

Standard deviation reflects the precision of the test

Front 23

Is determined by lab measurement of controls with known assay values

Back 23

Accuracy of test

Front 24

Using +/- 2 SD from the mean as the reference internal (normal value) for a test, 5% of the normal population is outside the normal range and have a ?

Back 24

FP test result
Repeating test usually produces a normal result.

Front 25

The mean of a test is 100 mg/dL and 1 SD equals 5 mg/dL. What is the reference internal (normal range) for the test?

Back 25

90-110 mg/dL

Front 26

The more tests you order, the greater the likelihood that one of the tests will be outside the reference interval.

Back 26

True
100 - (0.95^n x 100)
2 tests = ~ 10% FP
6 tests = 27% FP
6 Tests order on one Pt there is a 27% chance one of the tests will give a FP result.

Front 27

What serum tests are used for AMI?

Back 27

Serum CK-MB and troponins I and T

Front 28

How do u create a test with 100% sensitivity

Back 28

Set the upper limit of normal for the test at the beginning of the disease curve to create a test with 100% sensitivity.
Increase in FPs which decreases the specificity of the test.

Front 29

How do you create a test with 100% specificity

Back 29

Set the upper limit of the test at end of the normal cuve.
Increase in FNs, which decreases the sensitivity.

Front 30

In-Utero what is increased in Newborns

Back 30

HbF
EPO
Hb
UCB

Front 31

Newborn (NB) RBCs containing HbF are phagocytosed by and what is the end product

Back 31

Splenic Macrophages
Unconjugated bilirubin (UCB)
(responsible for physiologic jaundice, which begins on day 3)

Front 32

New RBCs in a newborn mainly contain

Back 32

HbA and HbA2
(HbF only 1%)

Front 33

Newborn Immunoglobulins

Back 33

No IgM at birth. Increase IgM in cord blood at birth indicates congenital infection.
Normal IgM synthesis begins at birth. IgG present in cord blood at birth is from the mother.
In infants, synthesis of IgG begins at 3 months.

Front 34

What Immunoglobulin can cross the placenta?

Back 34

IgG can cross the placenta

Front 35

EPO stimlulates

Back 35

Increase in RBC production and Hb synthesis

Front 36

In Children increased osteoblastic activity increases what?

Back 36

ALP increased
PHOS increased

Front 37

Describe ALP function
alkaline phosphatase

Back 37

ALP removes phosphate from pyrophosphate allowing bone to be mineralized.

Front 38

PHOS function

Back 38

Driving force for calcium mineralization of bone. Children have higher levels than adults.

Front 39

ALP is released from

Back 39

Osteoblasts

Front 40

What do children have lower levels of Hb concentration than adults

Back 40

Increased phosphorus increases synthesis of 2,3-bisphosphoglcyerate (BPG)
Increased BPG right-shifts the OBC, causing greater release of O2 to tissue.

Front 41

2,3-bisphosphoglycerate (BPG) does what to OBC

Back 41

Increased 2,3-BPG right-shifts the OBC, causing greater release of O2 to tissue.

Front 42

What are 2 factors which cause Hb differences in females and males.

Back 42

Females (Menses)
Males (testosterone)
Elderly males have a normal decrease in testosterone, which causes a normal drop in Hb to adult female levels.

Front 43

Testosterone stimulates erythropoiesis

Back 43

True

Front 44

Serum what are lower in women than in men.

Back 44

serum iron, ferritin, and Hb
causes: Menses, less testosterone

Front 45

Elderly can have a natural change in what lab?

Back 45

GFR & CCr decreased
ALP increased (osteoarthritis)
Hb decreased (only males)
Ig decreased (often lose natural blood group antibodies, anti-A IgM in group B person)

Front 46

Hospital pharmacy can adjust dose and time interval based on what to avoid what?

Back 46

Based on the age and the GFR of the patient to avoid nephrotoxicity.

Front 47

RBC mass is

Back 47

total number of RBCs in mL/kg

Front 48

Binding protein for iron

Back 48

transferrin

Front 49

Where is transferrin made

Back 49

Liver

Front 50

What gives stool its color

Back 50

Urobilinogen

Front 51

How is Urobilinogen derived

Back 51

degradation of conjugated bilirubin in the bowel by bacteria

Front 52

E. coli - describe UTI

Back 52

Frequent urination, burning
dipstick finding: Neutrophils, Urine nitrite, Urine leukocyte esterase positive

Front 53

Hemosiderosis

Back 53

Iron overload disease
ex. excessive blood transfusions

Front 54

In Hemosiderosis what are the expected lab values

Back 54

Increase in percent saturation of transferrin
Increased serum iron
TIBC decreased
Serum ferritin increased
Prothrombin time PT prolonged