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[Total blood volume in essential and secondary hypertension]
Insights
Total blood volume (TBV) is elevated in primary aldosteronism, a key factor in hypertension pathogenesis. Essential hypertension and Cushing's syndrome involve other unknown causes.
Area of Science:
- Endocrinology
- Nephrology
- Cardiovascular Medicine
Context:
- Hypertension is a complex condition with multifactorial origins.
- Volume factors, specifically total blood volume (TBV), are implicated in hypertension pathogenesis.
- Understanding these factors is crucial for developing effective treatment strategies.
Purpose:
- To investigate the role of total blood volume (TBV) in the pathogenesis of different types of hypertension.
- To compare TBV levels in patients with essential hypertension, primary aldosteronism, Cushing's syndrome, and renovascular hypertension against normotensive controls.
Summary:
- Total blood volume (TBV) was measured in hypertensive patients and controls using a radioisotope tracer technique under controlled sodium intake.
- Results showed increased TBV in primary aldosteronism, normal TBV in essential hypertension (regardless of plasma renin activity), and no TBV increment in Cushing's syndrome.
- Expanded intravascular volume is a significant mechanism in primary aldosteronism-induced hypertension with suppressed renin activity.
Impact:
- This study highlights the critical role of expanded intravascular volume in primary aldosteronism.
- It suggests that unknown factors contribute to hypertension in essential hypertension and Cushing's syndrome.
- Findings may guide future research into targeted therapies for volume-dependent hypertension.
Abstract:
To study the role of volume factors in the pathogenesis of hypertension, total blood volume (TBV) was determined in 43 patients with essential hypertension, 10 with primary aldosteronism, 5 with Cushing's syndrome, 5 with renovascular hypertension and 23 age-matched normotensives. The radioisotope (131I) labeled plasma tracer technique was employed under conditions of constant sodium intake (200mEq/day). The TBV values obtained were expressed as % normal against the predicted values according to the formulae of Fujita and his co-workers. The results were as follows: (1) TBV was increased in patients with primary aldosteronism. (2) In essential hypertensive patients, with either normal or low plasma renin activity, TBV was normal. (3) There was no increment of TBV in patients with Cushing's syndrome. These results suggest that expanded intravascular volume plays a major role in the mechanism of hypertension with suppressed plasma renin activity in primary aldosteronism, whereas other unknown factors may be related to the causes of hypertension in patients with essential hypertension and Cushing's syndrome.