Effects of acute hypercalcaemia on blood pressure in subjects with and without parathyroid hormone secretion.
OBJECTIVE
Acute hypercalcaemia increases the blood pressure, but the mechanism is uncertain. It may partly be the result of the concomitant fall in parathyroid hormone (PTH) secretion as PTH has been reported to have a vasodilator effect. To elucidate this, we infused calcium intravenously in subjects with and without PTH secretion.


METHODS
Seven thyroparathyroidectomized subjects with undetectable PTH levels and 10 controls were studied twice, once with a calcium clamp technique that increased plasma ionized calcium in two steps of 0.1 mmol L(-1), each step lasting 60 min, and once with a placebo infusion.


RESULTS
On the placebo day, blood pressure and all other variables were unaffected in both groups. On the calcium day, systolic blood pressure increased gradually and significantly from end of baseline till end of the calcium infusion in the controls (123.5 +/- 19.8 and 134.2 +/- 17.6 mmHg, P < 0.004) but not in the thyroparathyroidectomized subjects (124.9 +/- 15.7 and 126.0 +/- 20.6 mmHg, P = ns). Serum PTH levels fell promptly in the controls, and in both groups there was a significant increase in serum phosphate. The diastolic blood pressure and pulse rate, and the plasma adrenaline and noradrenaline, plasma renin activity, and serum aldosterone levels were unaffected by the calcium infusion.


CONCLUSIONS
During acute hypercalcaemia the blood pressure increase appears unrelated to catecholamine secretion and the renin-aldosterone system, whereas the fall in PTH secretion may play a contributory role.
Kamycheva
E
E
Department of Medicine, University Hospital of North Norway, Tromsø, Norway. elena.kamycheva@unn.no
Jorde
R
R
Haug
E
E
Sager
G
G
Sundsfjord
J
J
D000328:Adult; D001794:Blood Pressure / Q000502:physiology*; D002118:Calcium / Q000097:blood; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000503:physiopathology*; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood*; D016105:Parathyroidectomy; D010710:Phosphates / Q000097:blood / Q000652:urine; D013964:Thyroid Neoplasms / Q000601:surgery; D013965:Thyroidectomy
D010281:Parathyroid Hormone; D010710:Phosphates; D002118:Calcium