Preanalytical conditions that affect coagulation testing, including hormonal status and therapy

Preanalytical conditions, be they due to the individual's physiologic state or to exogenous factors, can affect coagulation factors, in either a transient or a persistent manner, and need to be considered in laboratory testing. These conditions include physical and mental stress, diurnal variation, hormone levels and posture at the time of blood drawing. While testing of these factors has not been exhaustive and some results are conflicting, guidelines for testing conditions can be given. © 2007 International Society on Thrombosis and Haemostasis.