Laboratory Medicine

Question 1

Plasma

Answer 1

supernatant after centrifugation of blood. Contains anitcoagulants to prevent clotting. used for chemistry tests

Question 2

Serum

Answer 2

allow blood to clot, supernatant is serum. Used for tests measuring antibodies.

Question 3

Whole blood

Answer 3

blood counts, heavy metals, transplant immunosuppressants

Question 4

Red top tubes

Answer 4

contains clot activators. takes 30 minutes. microclots can cause interference

Question 5

Serum separator tube

Answer 5

special gel that migrates between clot and serum to prevent clot contamination

Question 6

EDTA tubes (lavender or pink tops)

Answer 6

chelates Ca2+ and prevents clotting. CANNOT be used for Ca and Mg tests. Used for whole blood or plasma.

Question 7

Plasma separator tube

Answer 7

lithium heparin- after centrifugation, gel goes between plasma and cells. can’t be used for lithium drug levels

Question 8

Sodium Citrate (light blue top)

Answer 8

Tube of choice for coagulation tests (PT, PTT, coagulation factors). Must be filled accurately.

Question 9

Trace metal-free (royal blue)

Answer 9

certain trace metals-arsenic, cadmium, mercury, zinc. not needed for lead

Question 10

What tube would you use for serology?

Answer 10

red top tube

Question 11

What tube would you use for lead levels?

Answer 11

EDTA tubes (lavender or pink top)

Question 12

What tube would you use for serum?

Answer 12

serum separator tube

Question 13

What tube would you use for whole blood or plasma, and is used for hematology and molecular diagnostics?

Answer 13

EDTA (lavender or pink top)

Question 14

which tube cannot be used for lithium drug levels?

Answer 14

Plasma separator tube (lithium heparin)

Question 15

What tube would you use to analyze cadmium, mercury, arsenic, or zinc?

Answer 15

trace metal-free (royal blue)

Question 16

What tube would you use for coagulation tests Pt PTT?

Answer 16

Sodium citrate (light blue top)

Question 17

what tube has the common problem of not being filled fully resulting in elevated levels?

Answer 17

sodium citrate (light blue top)

Question 18

What order must blood draws be performed?

Answer 18

blood cultures (sterility) goes first. Tubes that can cross contaminate go at the end (EDTA).

Question 19

Poor blood draw technique or poor gauge needle choice can cause what testing issue

Answer 19

hemolysis. can also be caused by diseases such as malaria.

Question 20

Interference of testing due to hemolysis caused by what two mechanisms.

Answer 20

false elevation because RBC contain high amounts of AST, LDH (lactate DH), and K.
RBC lysis reduces what’s being measured, proteases degrade peptide like insulin.

Question 21

Lipemia in testing

Answer 21

turbid specimens usually due to high triglycerides. Extreme lipidemia >1000mg/dL can cause lipemia and hemolysis

Question 22

Icterus in testing

Answer 22

high bilirubin can lead to yellow plasma. very high bilirubin >40 mg/dL can interfere with chemistry tests.

Question 23

requirements on complexity of testing set by the CLIA

Answer 23

waived, moderate complexity, high complexity. Must have certificate to cover highest complexity in lab.