Renal sodium handling in patients with untreated hypertension and white coat hypertension.

Abstract

Renal tubular sodium handling was investigated prospectively in 48 normotensive subjects, 53 untreated hypertensive patients, and 13 patients with white coat hypertension using endogenous trace lithium as a marker of proximal sodium reabsorption. A 12-hour daytime ambulatory blood pressure recording was performed in all patients to confirm the diagnosis of hypertension. Patients were included in the white coat hypertension group if their office blood pressure was above 160/90 mm Hg but the mean value of their 12-hour ambulatory recording was lower than 140/90 mm Hg. All participants were studied on their normal diet and ate salt freely. Fractional excretions of sodium (FE N ,), lithium (FE U ), and potassium (FE K ) were measured simultaneously before blood pressure recording. FE Nl was significantly higher in hypertensive patients (0.84±0.05%, P<.05) than in normotensive control subjects (0.60±0.06%), and FE U was comparable in the two groups (15.4±0.65% in hypertensive patients and T he kidneys play a key role in the regulation of blood pressure and in abnormalities of renal function, including an increase in renal sodium reabsorption, which appears to be pivotal in the development and maintenance of experimental and clinical hypertension. The pressure-natriuresis mechanism is abnormal in all forms of chronic hypertension, suggesting that in hypertensive patients and animals, adequate renal sodium excretion is achieved only at elevated blood pressures.1 The nature of the renal abnormality leading to a rightward shift of the pressure-natriuresis curve in hypertension is still unknown. It may be the consequence of alterations in renal hemodynamics, as renal vascular resistance is almost invariably found to be increased in patients with hypertension, but it could also be due to abnormalities of renal tubular sodium reabsorption. 2So far, an increase in tubular sodium reabsorption leading to sodium retention has been difficult to show conclusively in hypertensive animals or patients. Nonetheless, some evidence in favor of this hypothesis has been accumulated over the past 10 years. The first attempts to characterize renal sodium handling in normotensive and hypertensive animals were done using micropuncture studies. However, the need for anesthesia and surgery, which modify renal hemodynamics and Received November 9, 1993; accepted in revised form December 28, 1993. From the Policlinique M6dicale Universitaire, Divisions of Hypertension and of Clinical Pharmacology, Lausanne, Switzerland.Correspondence to Dr M. Burnier, MD, Policlinique M6dicale Universitaire, Rue Cisar Roux 19, 1005 Lausanne, Switzerland.17.0±0.9% in control subjects). However, the relation between FE Nl and FE U was significantly different in normotensive subjects and hypertensive patients (/ ) <.001), so that for a given increase in FE Nl a smaller increase in FE U was observed in hypertensive patients. In addition, the ratios of urinary lithium to sodium and urinary potassium to sodium were significantly reduced in hypertensive pati...

Association Between Arterial Properties and Renal Sodium Handling in a General Population

“…Vasoconstriction is the hallmark of hypertension. Animal models of hypertension, 18 hypertensive patients, 19 normotensive subjects with 1 first-degree relative with hypertension, 20 and patients with white-coat hypertension 19 have higher RNa prox . Moreover, Draaijer et al 21 reported a significantly lower arterial compliance in sodium-sensitive than in sodium-resistant men with borderline hypertension, independent of cardiac output, blood pressure, and hormonal factors.…”

Is elevation of clinic blood pressure in patients with white coat hypertension who have normal ambulatory blood pressure associated with target organ changes?

“…1 Variously termed 'white coat hypertension', 'clinical hypertension', or 'isolated clinic hypertension' 2 (we will herein refer to the phenomenon as white coat hypertension (WCH)), it has been assumed that the lack of sustained hypertension in these patients reflects a reactive sympathetic nervous system, and predicts a benign prognosis. A number of studies looking at evidence of target organ damage have given equivocal results; left ventricular hypertrophy and renal dysfunction have both been described as occurring in association with WCH, [3][4][5][6][7][8] while other studies have not documented an association. [9][10][11][12] These studies have largely shown significantly higher mean BP in the WCH group, and it may be that the documented elevation of cardiac and renal indices of end-organ involvement found Conclusion: White coat hypertension is indeed associated with a larger left ventricular muscle mass than normotensives and these changes are independent of the actual 24-h BP load, and may reflect increased BP lability, sympathetic nervous system derangement, or a genetic propensity in people with white coat hypertension to stress-related hypertensive reactions, as part of a pre-hypertensive state.…”

Pressure response to successive clinic readings predicts an elevated blood pressure at 2.6 years’ follow-up: The Israeli CORDIS Study

“…However, generalizing from recent findings concerning white-coat 0.615). These findings if replicated in future studies, may contribute to the long-standing efforts to prehypertension, 20,21 we may hypothesize that the excessive pressure response might signify a prehydict later sustained hypertension in persons with high-normal baseline BP values. Further analysis of pertensive state.…”

“…On the basis of evidence suggesting that responses to standardized laboratory stressors. 4,8 white-coat hypertension may represent a prehypertensive state, 20,21 we formulated the working hypothesis that individuals exhibiting an exagger-BP values to BP determination) would display an Psychological tests elevated baseline BP on follow-up, compared to low To explore whether over-responsivity to BP determiresponders. We tested this hypothesis in a large samnation may be associated with certain personality ple of industrial male workers (excluding medicated dispositions and/or psychoneurotic symptoms, the hypertensives) who were followed up for 2-4 years.…”