Effects of PTH(1-34) on Blood Pressure, Renal Function, and Hormones in Essential Hypertension The Altered Pattern of Reactivity May Counteract Raised Blood Pressure

Abstract

As it has been suggested that parathyroid hormone (PTH) is implicated in the pathophysiology of essential hypertension, the effects of PTH(1-34) were assessed during infusion over 120 min in ten men with essential hypertension and in ten healthy men. Ionized calcium was kept constant by a clamping technique. Mean arterial blood pressure fell slightly in the patients (116 mm Hg, median, before, and 108 mm Hg during the infusion, P < .01), but remained unchanged in the controls (median 87 mm Hg). The pulse rate rose to a similar extent in the two groups, but cardiac output, measured by the CO2 rebreathing technique, was unchanged. The glomerular filtration rate (GFR) was slightly lower in the hypertensives than in the controls at baseline (92 v 109 mL/min, P < .02), but it increased similarly during PTH infusion in both groups (+13% v +9%, medians), as did the effective renal plasma flow (+50% v +38%). The urinary rate of sodium excretion, which was similar at baseline, increased more in the patients than in the controls (+191% v +46%, P < .05); this was mainly attributable to a reduction in the tubular reabsorption of sodium. Calculations based on lithium clearance indicated that mainly the proximal tubular reabsorption of sodium decreased during PTH infusion. Baseline plasma PTH(1-84) was higher in the patients than in the controls (20.5 ng/L v 16.5 ng/L, P < .05). The baseline plasma values of renin, aldosterone, atrial natriuretic peptide, endothelin, and noradrenaline were similar in the two groups. During infusion of PTH, renin increased less in the patients than in the controls (P < .02), and aldosterone increased only in the controls (P < .01). The other hormonal values remained unchanged. In conclusion, the patients with essential hypertension had increased baseline PTH values, but nevertheless PTH had more marked vasodilative and natriuretic effects than in the controls. PTH thus seems to counteract rather than aggravate elevation of blood pressure in these patients.

Population based study on serum ionised calcium, serum parathyroid hormone, and blood pressure. The Tromso study

“…Thus, Hulter et al (35) found that a 12-day chronic PTH infusion in normal subjects caused hypertension, an effect however, that could also be the result of the accompanying hypercalcaemia. On the other hand, in the elegant study by Jespersen et al (36), serum ionised calcium level was kept constant by a clamping technique, and a 120-min infusion with PTH caused a reduction in mean arterial blood pressure in hypertensive men. This obviously needs further study, and could possibly have therapeutic implications.…”

Long-term Outcomes of Parathyroidectomy in Kidney Transplant Recipients with Persistent Hyperparathyroidism

“…This hypothesis was proven by a study showing that intradialytic hypotension was significantly improved after PTX in maintenance hemodialysis patients with secondary HPT [15], in agreement with our findings of the successful correction of hypercalcemia after PTX. In animal and human studies, acute exposure of PTH seemed to reduce BP as a result of the vasodilatory effect [16,17], whereas chronic exposure could induce hypertension through inducing the accumulation of calcium in vascular smooth muscle cells [16,18]. However, we failed to demonstrate the correlation between the reduction of serum calcium or iPTH level and the change of the SBP, DBP and PP after PTX.…”

Ação local do alendronato sódico na reparação óssea de ratos espontaneamente hipertensos (SHR)

“…In the systemic arterial hypertension, the low levels of calcium ions in the serum, mainly due to the hypercalciuria, can stimulate the compensatory increase in the production of PTH, the main hormone related to the control of the plasmatic level of calcium in the organism. In this way, high levels of PTH tend to contribute to the process of bone remodeling, as they stimulate the osteoclastic activity and mobilize the calcium in the skeleton, and could lead to the decrease of the bone mineral density 20 .…”