A patient is admitted through the hospital emergency department ...

[OSWALD]

A patient is admitted through the hospital emergency department with thrombosis, and heparin is initially begun. Her baseline PTT, before heparin therapy, is prolonged at 68 seconds.
 
  Further laboratory studies determine that she has the lupus anticoagulant. What test should be used to monitor her heparin therapy?
 
  a. PTT
  b. PTT after first adding antithrombin to her plasma
  c. Chromogenic anti-Xa assay
  d. TT after first making a 1:10 dilution of the patient plasma

Question 2

Unfractionated heparin is commonly monitored by the:
 
  a. PT
  b. Partial thromboplastin time (PTT)
  c. Thrombin time (TT)
  d. Kinetic fibrinogen

[anyusername12131]

Answer to Question 1

ANS: C
The PTT is already prolonged by the lupus anticoagulant, so the heparin therapeutic range for the PTT reagent becomes meaningless. In this case a chromogenic anti-Xa assay should be used.

Answer to Question 2

ANS: B
The PTT is the most commonly used test for monitoring heparin therapy because it responds in a linear fashion over the therapeutic range. The PT is relatively insensitive to heparin, whereas the TT is too sensitive. The kinetic fibrinogen is the least sensitive of these tests to therapeutic heparin.

[OSWALD]

Gracias!

[jomama]

TYSM