A patient has an elevated thrombin time and normal reptilase ...

[mia]

A patient has an elevated thrombin time and normal reptilase time. Which of the following situations is most likely?
 
  a. Heparin therapy
  b. Low fibrinogen
  c. Elevated fibrin split products
  d. Dysfibrinogenemia

Question 2

A prolonged PTT is corrected when mixed with normal plasma and tested immediately and after a 2-hour incubation. Which test (or tests) should be performed next?
 
  a. Bethesda titer
  b. High phospholipid PTT
  c. Anti-Xa assay
  d. Factor VIII and IX assays

[durant1234]

Answer to Question 1

ANS: A
Heparin prolongs the thrombin time but does not prolong the reptilase time. A low fibrinogen, elevated fibrin split products, and dysfibrinogenemia prolong both, although differences exist in sensitivity to some of these between the two tests.

Answer to Question 2

ANS: D
This pattern suggests a factor deficiency, and factor VIII and IX assays should be performed. The Bethesda titer is performed when a specific factor inhibitor is present; no evidence exists for this because the PTT on the incubated 1:1 mix did not prolong. High phospholipid PTT testing is done to confirm the lupus anticoagulant; this is not present because the immediate 1:1 mix on this sample corrected. No reason exists to perform an anti-Xa assay, often used to monitor LMWH.

[mia]

Excellent

[mochi09]

TYSM