According to NCCLS guidelines, the following times for receipt in the laboratory will be required for processing a partial thromboplastin time (PTT): if patient is on heparin therapy, samples must be in the lab within one hour after draw. All other samples must be tested within four hours. Samples will be rejected beginning September 24, 2001, if the time limit is exceeded.

If there are questions, call the Hemostasis Laboratory, 356-3573.