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Urinary calcium excretion in essential hypertension.
E W Young1, C D Morris, D A McCarron
1Division of Nephrology, Oregon Health Sciences University, Portland 97201.
The Journal of Laboratory and Clinical Medicine
|October 1, 1992
Summary
Essential hypertension is linked to higher urinary calcium excretion (UCaV), particularly under controlled sodium intake. This calciuria correlates with blood pressure but doesn't stem from altered intestinal calcium absorption.
Area of Science:
- Nephrology
- Cardiovascular Medicine
- Nutritional Science
Background:
- Essential hypertension is associated with elevated urinary calcium excretion (UCaV).
- The underlying causes of increased UCaV in hypertension are not fully understood.
- Dietary factors are hypothesized to contribute to calciuria in hypertensive individuals.
Purpose of the Study:
- To investigate the relationship between essential hypertension and urinary calcium excretion.
- To test the hypothesis that dietary factors influence calciuria in hypertension.
- To evaluate alternative mechanisms for increased UCaV in hypertensive patients.
Main Methods:
- Compared UCaV in 15 hypertensive patients and 16 normotensive controls.
- Assessed UCaV under free-living and controlled sodium intake diets (88 mEq).
- Administered oral calcium loads and measured serum ionized calcium and UCaV.
Main Results:
- No significant difference in UCaV between groups on self-selected diets (p=0.1).
- Significantly higher UCaV in hypertensive subjects on controlled diets with 400 mg and 1400 mg calcium (p=0.02).
- UCaV directly correlated with systolic blood pressure (r=0.63, p<0.001).
- No difference in intestinal calcium absorption or fasting UCaV between groups.
Conclusions:
- Hypertension is associated with increased urinary calcium excretion, especially under restricted sodium intake.
- Dietary calcium intake significantly impacts UCaV in hypertensive individuals.
- The calciuria of hypertension is not explained by impaired intestinal calcium absorption.