Instructions on appropriate fasting prior to phlebotomy; effects on patient awareness, preparation, and biochemical parameters.

Objectives: This study investigated the effect of appropriate pre-phlebotomy instructions on patients' awareness of the need to fast, their fasting status at phlebotomy, and the measurement of specific biochemical analytes and indices.

Methods: While booking their phlebotomy appointments, two-hundred outpatients, with a wide range of pre-existing medical conditions, were recruited and randomly assigned to either control or intervention groups. The control group received no instructions while the intervention group was verbally instructed to fast for precisely 12 h prior to their appointment.