A patient on heparin therapy has a PTT of 50 seconds. Is this within the therapeutic range?

• A. Yes, within range
• B. No, too high
• C. No, too low
• D. Cannot determine from this information

Answer: (A)

When a patient is on unfractionated heparin, the PTT is used to gauge how anticoagulated they are. The therapeutic goal is to achieve about 1.5 to 2.5 times the patient’s baseline PTT (the lab’s normal control). Since heparin lengthens clotting time, a PTT value in this range indicates adequate anticoagulation without excessive bleeding risk.

A PTT of 50 seconds typically falls within that therapeutic window for most labs, given a normal control PTT around 25–35 seconds. If the value were consistently much higher, you’d reduce the dose; if consistently lower, you’d increase it. Always compare to the specific lab’s control value to confirm.