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Calcium metabolic indices, vascular retinopathy, and plasma renin activity in essential hypertension
A Hvarfner1, C Mörlin, H Präntare
1Department of Internal Medicine, University Hospital, Uppsala, Sweden.
Insights
Low plasma ionized calcium is an independent risk factor for vascular disease in essential hypertension. This study found inverse relationships between ionized calcium and blood pressure, and associations with retinopathy.
Area of Science:
- Cardiology
- Nephrology
- Ophthalmology
Background:
- Essential hypertension is a complex condition with multifactorial etiology.
- Calcium metabolism and its relationship with blood pressure regulation are not fully understood.
- Vascular complications, such as retinopathy, are significant concerns in hypertensive patients.
Purpose of the Study:
- To investigate the interplays between calcium metabolic indices, retinal vascular status, plasma renin activity, and blood pressure in untreated essential hypertension.
- To determine if plasma ionized calcium is an independent risk factor for vascular disease.
Main Methods:
- Cross-sectional study of 67 patients with untreated essential hypertension.
- Measurement of calcium metabolic indices (plasma ionized calcium, albumin-modified total serum calcium, plasma cyclic AMP, 24 h urinary cyclic AMP).
- Assessment of retinal vascular status and plasma renin activity.
- Statistical analyses including analyses of covariance to account for confounding factors.
Main Results:
- An inverse relationship was observed between plasma ionized calcium and blood pressure (P = .002).
- Albumin-modified total serum calcium, plasma cyclic AMP, and 24 h urinary cyclic AMP were positively associated with blood pressure.
- Patients with retinopathy had lower plasma ionized calcium and higher 24 h urinary cyclic AMP excretions, independent of blood pressure and other factors.
- Plasma renin activity did not influence the observed relationships.
Conclusions:
- Low plasma ionized calcium concentration is an independent risk factor for vascular disease in essential hypertension.
- Calcium metabolic indices, particularly plasma ionized calcium, play a significant role in the pathophysiology of hypertension and its vascular complications.
- Further research is warranted to explore therapeutic strategies targeting calcium metabolism for hypertension management.
Abstract:
The interplays between calcium metabolic indices, retinal vascular status, plasma renin activity and blood pressure were examined in 67 patients with untreated essential hypertension. There was an inverse relationship between plasma ionized calcium and blood pressure (P = .002), whereas albumin-modified total serum calcium was directly related to blood pressure (P = .02). The plasma cyclic AMP level (P = .05) and the 24 h urinary excretion of cyclic AMP (P = .03) were also positively associated with blood pressure. Patients with vascular retinopathy had lower plasma ionized calcium concentrations (P = .01) and higher 24 h urinary cyclic AMP excretions (P = .05) than those without such changes, even when the differences in blood pressure, age, sex and body mass index were taken into account in analyses of covariance. Plasma renin activity did not interfere with the relationships between calcium metabolic indices and blood pressure, nor were there any associations between the renin status and the calcium metabolic indices. These findings suggest that a low concentration of plasma ionized calcium is an independent risk factor for vascular disease.