Intro to Lab Medicine (Krasowski)

Question 1

mass spectrometry test that can can identify a microbe down to the species, bypassing biochemical testing

Answer 1

MALDI-ToF

Question 2

serology tests detecting antibodies commonly require this type of sample, which is drawn following a period of clotting

Answer 2

serum

Question 3

test that uses an electrical field to separate the proteins in the blood serum into groups of similar size, shape, and charge; useful for diagnosing myeloma

Answer 3

serum protein electrophoresis

Question 4

this is the most appropriate sample for measuring lead level and relies on anticoagulation

Answer 4

whole blood

Question 5

most chemistry tests use this type of sample, to which anticoagulants (ie, EDTA, heparin) are added

Answer 5

plasma

Question 6

tubes with this color top indicate ‘no additives’ - meaning no anticoagulants have been added - and are useful for serology and protein electrophoresis

Answer 6

red

Question 7

what are the drawbacks associated with samples in a red top tube?

Answer 7

they contain clot activators, so the turnaround time is rather slow (takes at least 30 minutes to clot) and microclots can form and interfere with automated instruments

Question 8

this type of tube has clot activators as well as a special gel that separates the serum from the clotted RBCs; handy for samples that need to be sent out to a reference lab

Answer 8

serum separator tube

Question 9

tube with a lavendar or pink top that contains a calcium chelator which prevents clotting; useful for tests that require whole blood (e.g., lead and DNA)

Answer 9

EDTA tube

Question 10

tube with a light green top that uses the anticoagulant lithium heparin to separate plasma from the RBCs, whose separation is maintained by a layer of gel

Answer 10

plasma separator tube (PST

this is the tube of choice for all chemical assays at UIHC but CANNOT be used for lithium drug tests because of the lithium heparin

Question 11

light blue top tube used for coagulation testing, whose main drawback is inadequate filling, leading to too much anticoagulant relative to blood

Answer 11

sodium citrate tube

Question 12

tubes with this color top are required for certain trace metal analysis (e.g., arsenic, copper, mercury, etc.)

Answer 12

royal blue

Do NOT need for lead testing

Question 13

problem seen in lab testing that is associated with poor draw technique (e.g., use of a narrow gauge needle, rapidly forcing blood from syringe into tube, contamination by IV fluids or drugs)

Answer 13

hemolysis

Question 14

True or false: hemolysis is problematic in lab testing because it may falsely elevate insulin levels.

Answer 14

False. When red blood cells lyse, proteases escape that break down insulin, which would cause an artificially low reading;
Hemolysis would cause, however, elevated readings of AST, LDH and potassium

Question 15

a turbid specimen is most often due to elevated levels of _____, and this is known as ______.

Answer 15

triglycerides; lipemia

Question 16

hypertriglyceridemia may lead to this condition, characterized by pain in the upper abdomen, nausea and vomitting

Answer 16

pancreatitis

Question 17

yellow discoloration of the skin due to hyperbilirubinemia in the newborn and often attributed to chronic alcoholism in the adult

Answer 17

icterus (jaundice)

Question 18

law revised in 2003 that established federal government oversight of clinical laboratories, including small labs in doctors’ offices, and requires that sites have coverage at the highest level of complexity of testing in their laboratory

Answer 18

clinical laboratory improvement act (CLIA)

Question 19

Which of the following laboratory studies is MOST LIKELY affected by a specimen that is hemolyzed?

A. Aspartate aminotransferase (AST)
B. Creatinine
C. Lipase
D. Chloride
E. Prolactin

Answer 19

A

Question 20

What is MOST LIKELY cause of a glucose value of 1,200 mg/dL in a non-diabetic patient?

A. Interference by hemolysis
B. Inappropriate use of sodium citrate tube
C. Interference by lipemia
D. Draw from contaminated IV line
E. 8 Hour delay prior to specimen processing

Answer 20

D

Question 21

In general, what is the proper draw order for tubes?

Answer 21

those requiring sterility (ie blood culture) are drawn first;

those that contain additives are drawn later, e.g.:
Red top serum separator and lt. blue top sodium citrate tubes for coagulation

EDTA tubes for lead, DNA

Plasma separator tubes (w/lithium heparin) for chemicalk assays

Question 22

extreme lipemia is defined by triglycerides > _____, and this can interfere with tests and lead to hemolysis in the test tube

Answer 22

1000 mg/dL

Question 23

very high bilirubin levels of >_____ can lead to test cancellation

Answer 23

40 mg/dL