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Haemodynamic and hormonal changes during acute and chronic diuretic treatment in essential hypertension
Insights
Chlorthalidone treatment for hypertension initially causes volume depletion and hormonal changes. Long-term blood pressure response depends on complex adaptations, not initial reactions.
Area of Science:
- Nephrology
- Cardiovascular Medicine
- Pharmacology
Background:
- Essential hypertension is a prevalent cardiovascular risk factor.
- Diuretic therapy, like chlorthalidone, is a cornerstone in hypertension management.
- Understanding treatment effects on haemodynamic and hormonal parameters is crucial.
Purpose of the Study:
- To investigate the short- and long-term effects of chlorthalidone on haemodynamic and hormonal parameters in essential hypertension.
- To determine factors influencing blood pressure response to diuretic therapy over time.
Main Methods:
- Patients with essential hypertension (WHO grade I) received chlorthalidone 50 mg/day.
- Haemodynamic (BP, HR, BV, ECV) and hormonal (PRA, PA, UNE) parameters were measured at baseline, 3 days, and 3 months.
- Renin dependency was assessed using saralasin response.
Main Results:
- Short-term (3 days): Increased PRA, PA, UNE, HR; decreased BW, ECV, BV. Variable BP changes correlated with BV.
- Long-term (3 months): Volume depletion signs lessened, but low ECV persisted. BP changes correlated inversely with ECV and renin dependency, and positively with PRA and UNE.
Conclusions:
- Blood pressure response to chlorthalidone is determined by adaptive haemodynamic changes to volume depletion over time.
- Predicting long-term BP response based on initial parameters or acute changes is not feasible.
Abstract:
The short- and long-term effects of diuretic treatment with chlorthalidone 50 mg/day on haemodynamic and hormonal parameters in patients with essential hypertension (WHO grade I) were investigated. After three days of treatment, all patients showed a rise in plasma renin activity (PRA), plasma aldosterone (PA), urinary norepinephrine excretion (UNE) and heart rate (HR), and a decrease in body weight (BW) and extracellular volume (ECV) and blood volume (BV); the change in blood pressure (BP) was variable. The changes in BP were correlated with those in BV. After three months of therapy, the signs of volume depletion tended to fade, but the lower ECV persisted. In contrast to the 4-day study, after three months the change in BP correlated inversely with changes in ECV and renin dependency (saralasin response), and positively with PRA and changes in UNE. It is concluded that the BP response to diuretic treatment is determined by the adaptation with time of the haemodynamic reactions to the volume-depleted state. Whether this adaptation will take place cannot be predicted from the control values of the parameters studied, or from acute changes observed during the first days of treatment.