Effect of placebo on office and on 24 hour noninvasive ambulatory blood pressure measurements.

Elevated BP in the clinical but not during daily activities (white coat hypertension) is a well recognised problem encountered in the diagnosis of mild hypertension. The aim of this study is to evaluate this phenomenon with a study population of 90 mild hypertensive patients subjected to 24h BP measurement, and to assess the effect of placebo on both the office and the daytime continual BP monitored values. For this purpose, 90 patients were evaluated after four weeks of single-blind placebo (Phase I) and, of these, 27 patients were evaluated after a further four weeks of double-blind placebo administration (Phase II). During Phase I treatment the mean office SBP (163.9 mmHg) and the mean office DBP (104.5 mmHg) were significantly higher than the average of the six readings obtained during the first two hours of automatic continual BP monitoring (158.6 and 98 mmHg respectively, P < 0.001) (white coat effect). These differences were much more pronounced when the comparison was made between office measurements and the average daytime values (SBP 152.8 mmHg, DBP 93.1 mmHg). At the end of Phase II, the average values of BP measurements obtained both in the office and from continual monitoring were significantly lower (placebo effect). However, the difference between the office and the daytime values persisted. Thus, notwithstanding the reduction in the BP measurements following placebo administration, the white coat effect persists.

Atrial natriuretic peptide in diabetic patients before and after control of blood sugar level.

Atrial natriuretic peptide (ANP) was examined in 20 diabetic patients: 10 patients referred from the emergency room with severe hyperglycemia, (Group A), and 10 patients with uncontrolled diabetes referred by the outpatient clinic (Group B). Seven patients from Group A reached the nadir of less than 10 pg/ml, and three reached 12-16 pg/ml; following equilibration of sugar level, mean ANP level rose to 51.4 pg/ml (SD +/- 5.6). In Group B mean ANP level before treatment was 19.2 pg/ml +/- 11.4, and after diabetes control reached 40.4 pg/ml (SD +/- 10.04). Findings demonstrate a significant decrease in ANP in the acute hypoglycemic state, and a return to normal levels when sugar is controlled and hypovolemia corrected. Patients with chronic hyperglycemia exhibit compensation of intravascular volume. It seems that the equilibration system functioning via ANP is highly sensitive as a result of acute changes in total body fluid, and becomes desensitized during chronic disequilibrium.