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Low renin hypertension comprises a spectrum of disorders ranging from primary aldosteronism to obvious disorders of other mineralocorticoids, as well as a variety of miscellaneous disorders. The largest group of patients with low renin hypertension have no clear abnormality in mineralocorticoid production. However, many lines of evidence suggest the critical role of volume excess in the pathogenesis of hypertension in these patients. More detailed physiological studies must be performed in order to totally understand the spectrum of pathophysiology in low renin hypertension. However, while such studies are in progress the evidence from the literature suggests that these patients must be treated and that in most of these patients diuretic administration, either spironolactone or the thiazide group of diuretics, is usually effective in achieving a reduction of blood pressure to normal. more...

The Hypertension Detection and Follow-up Program (HDFP) first demonstrated that treatment of patients with mild hypertension (90 to 104 mm Hg diastolic) could reduce morbidity and mortality in coronary heart disease (CHD). Previous studies had already shown the beneficial effect of blood pressure reduction on renal disease, heart failure, and cerebrovascular disease. When uncontrolled, mild hypertension in the patient with renal disease will lead to further deterioration of renal function. To prevent this and other complications (such as atherosclerosis) of hypertension, whether primary or secondary, one should place these patients on antihypertensive therapy. However, standard stepped-care therapy with diuretic drugs and beta-blocking agents is now under reevaluation in view of the potential adverse effect of these agents on serum lipids and renal function. Beta-blocking drugs, furthermore, tend to increase peripheral resistance, a hemodynamic effect opposite to that desired in these patients. Other drugs, acting centrally or peripherally on the nervous system, also have some undesirable features in addition to troublesome side effects. Prazosin, a vasodilator and effective antihypertensive agent with a different mechanism of action, has no adverse action on lipids and renal function, lowers peripheral resistance, and does not cause many of the side effects that limit use of the other drugs. It therefore appears to be a good choice for initial therapy in mild to moderate hypertension with associated renal insufficiency. more...

We used digital intravenous subtraction angiography (DSA) to evaluate 105 patients with suspected renovascular hypertension. Unilateral renal artery stenoses were identified in 14 patients, two of whom had previously had contralateral nephrectomy. In addition, one of three renal transplant recipients was found to have stenosis of the nutrient artery. Bilateral renal artery stenosis was demonstrated by DSA in three patients. Of the 88 patients who had concomitant minute sequence (hypertensive) urography (HIVP) delayed excretion suggested a renal artery lesion in only 8 patients. In the group of 88 patients, HIVP was able to detect renal artery stenosis in only 50% (eight of the 16) of patients whose stenosis was detected by DSA. When the patients with a single kidney are excluded, HIVP showed 62% (eight of 13) of the lesions detected by DSA. There were no significant complications in the patients examined by either modality. DSA has replaced HIVP as the screening examination for renovascular causes of hypertension in our institution. more...

A prospective study was undertaken to evaluate the relative contribution of changes in sympathetic nervous system activity, as reflected by changes in dopamine-beta-hydroxylase (DBH) activity, to the pathogenesis of oral contraceptive-induced hypertension. Precontraceptive and serial post contraceptive determinations of blood pressure, plasma renin activity (PRA), DBH activity, and changes in body weight were obtained in twelve control patients and forty-one oral contraceptive users. Forty-four percent of oral contraceptive users had increases in blood pressure but remained normotensive and 17% became frankly hypertensive. The precontraceptive and average post contraceptive levels of mean arterial pressure (MAP), PRA and DBH activity in each patient were compared using paired group analysis. Control patients (group I) exhibited no significant changes in these variables, while the patients with contraceptive-induced increases in MAP (groups III and IV) underwent significant, parallel increases in DBH activity. Finally, the linear regression of changes in MAP on the percent change in DBH activity was examined. The positive slopes in groups III and IV differed significantly from the negative slope of the controls (group I). The data have been interpreted to reflect an inappropriate oral contraceptive-induced stimulus to sympathetic nervous system activity, leading to increases in MAP in susceptible individuals. more...

A single evening dose of a clonidine-chlorthalidone combination (Combipres) was compared with the usual twice-daily schedule in 11 patients with essential hypertension. No significant difference was found between the blood pressures recorded on the two regimens or between morning and afternoon pressures on the once-daily schedule. Only one patient did not maintain adequate blood pressure control. We suggest that some patients with essential hypertension can be adequately treated with a single daily dose of a combination of clonidine and chlorthalidone. more...

The activity of dopamine beta-hydroxylase (DBH) in plasma ranged from 2 to 100 units per liter of plasma in 82 apparently healthy subjects (ages 22 to 35 years). A nonnormal pattern of distribution was evident: 62 subjects had values below 35 units (18 +/- 1), while 13 of the remaining 20 subjects had values above 60 units (80 +/- 5). Those with low DBH activity had lower values for urinary catecholamine excretion (31 +/- 3 micrograms), with normal and stable blood pressure; those with high DBH activity had higher values for urinary catecholamine excretion (72 +/- 6 micrograms), with greater lability of arterial blood pressure. The DBH activity was significantly elevated in patients with labile (74 +/- 2 mm-Hg) or fixed (57 +/- 2 mm-Hg) essential hypertension. The results indicate that plasma DBH activity is low and that it falls within a narrow range in young adults with normal and stable blood pressure. more...