To explore the mechanisms of the "white coat" phenomenon, the effects of talking, reading, and silence were analyzed. Fifty essential hypertensive patients were randomly allocated to periods of stress talking and relaxing reading, alternating with three periods of silence. While talking, systolic/diastolic blood pressure increased sharply, from 142 +/- 0.7/97.7 +/- 0.5 mm Hg to 159 +/- 0.7/111 +/- 0.5 mm Hg (P < .0001). While reading, systolic/diastolic blood pressure decreased (P < .0001). Moreover, talking and reading had opposite residual effects. The silence and reading periods gave the best approximations of the daytime ambulatory period. The predictive value of clinical blood pressure can be improved if measured during a period without talking, thus decreasing the "white coat" phenomenon.

Talking has been shown to increase blood pressure instantaneously in hypertensive patients and to contribute to the white coat effect. The effects of talking were compared with those of counting aloud in 64 patients with essential hypertension who were randomly assigned to a period of stress talking and a period of counting aloud (active periods), alternating with three periods of silence (control). The same monitor was used for office measurements and 24-hour ambulatory blood pressure analysis. Systolic/diastolic blood pressures increased significantly more during talking (163/110 mmHg) than during counting aloud (152/102 mmHg, both p < .0001) in both treated and untreated patients and in sustained and clinical hypertension. Talking had a residual effect on systolic blood pressure that lasted 5.8 +/- 0.1 minutes. The emotional content seemed to be the only cause of the talking effect. Its instantaneous and residual effects on blood pressure and heart rate should be considered when measuring these variables.

IntroductionFibroblast growth factor 23 (FGF23) could contribute to cardiovascular morbidity in chronic kidney disease. In studies of kidney transplant recipients, a high circulating level of FGF23 has been associated with death and graft loss independently of estimated glomerular filtration rate (GFR). Whether FGF23 is associated with adverse outcomes in the early posttransplantation period is unknown.MethodsWe analyzed a cohort of 845 kidney transplant recipients in stable condition who had GFR measured in the first years after transplantation with a median follow-up of 71 months.ResultsA high FGF23 concentration was associated with death or graft loss in univariate analysis, but this association was lost after adjustment for measured GFR. In contrast, FGF23 remained significantly associated with the composite outcome when estimated GFR was substituted for measured GFR. We also observed that follow-up duration modified the association between FGF23 and outcome. Although FGF23 was not associated with any endpoint in the full duration of the study, we found an independent association between FGF23 and the incidence of graft loss within the 4 years after FGF23 measurement. We did not find an association between FGF23 levels and left ventricular mass in a subgroup of 227 patients who had echocardiography performed within 3 months of FGF23 measurement.DiscussionThis study demonstrates that FGF23 measured during the first year after transplantation is not an independent predictor of death and graft loss and is not associated with left ventricular hypertrophy in the posttransplantation period. It further unveils important factors modifying the association between FGF23 and outcome in this population.

Both white coat effect (the tendency of blood pressure to rise during a medical visit) and talking effect were analyzed in 42 patients with essential hypertension. Blood pressure was measured during the clinic visit and over the subsequent 24-hour ambulatory period, with the physician performing 49 +/- 4 measurements for each patient. Three silent periods and two talking periods (stress and relaxation) were randomly allocated in a crossover design and studied, using analysis of variance. During the initial 11-minute silent period, systolic/diastolic blood pressures increased by 6 mm Hg/5 mm Hg. During the subsequent talking periods, these variations were significantly greater: +22 mm Hg/+17 mm Hg. Measures of systolic/diastolic blood pressure were higher during stressful talking than during relaxed talking. The talking and its emotional contents seemed to explain 70% of the white coat phenomenon. To minimize the white coat phenomenon in the clinic, physicians, nurses, and clinicians are advised to measure blood pressure during an initial period of silence.