White coat effect--problem of assessing its incidence and magnitude in children.

The aim of this study was an attempt to assess the incidence and estimate the method of calculating the magnitude of white coat effect (WCE) in healthy children. 59 healthy children aged 10-18 years underwent office blood pressure (BP) measurement and 24-hour ambulatory blood pressure monitoring (ABPM). WCE magnitude was evaluated according to the generally accepted method, as the difference between office BP and mean daytime ambulatory BP value. WCE magnitude calculated in that way was negative in 49 % children, and positive in 51 % children. Systolic blood pressure WCE ranged from (-43.79) to (+44.35) mmHg; the mean value was (+1.60) mmHg. Diastolic blood pressure WCE ranged from (-66.14) mmHg to (+48.00) mm Hg, and the average was (-1.47) mmHg. 1. Positive WCE was observed in about 50 % of the examined children. 2. Mean daytime ambulatory BP level in children may be greater than office BP level. It may be the consequence of a higher level of physical activity in children than in adults. 3. The generally accepted method of calculating WCE magnitude in adults seems inappropriate for children. 4. Introducing a new method of evaluating WCE in children (different from that used in adults) may be worth consideration.