Parathyroid hormone in blood pressure and volume homeostasis in healthy subjects, hyperparathyroidism, liver cirrhosis and glomerulonephritis. A possible interaction with angiotensin II and atrial natriuretic peptide

Intravenous calcitriol regresses myocardial hypertrophy in hemodialysis patients with secondary hyperparathyroidism

To evaluate the response of circulating intact parathyroid hormone (iPTH) on myocardial hypertrophy in hemodialysis (HD) patients with secondary hyperparathyroidism (SHPT), echocardiographic and neurohormonal assessments were performed over a 15-week period in 15 HD patients with SHPT before and after calcitriol treatment and 10 HD control patients with SHPT not receiving calcitriol therapy. We prospectively studied a group of 15 patients with significantly elevated iPTH levels (iPTH >450 pg/mL) receiving calcitriol (2 microg after dialysis twice weekly). Clinical assessment, medication status, and biochemical and hematological measurements were performed once a month. Throughout the study, calcium carbonate levels were modified to maintain serum phosphate levels at less than 6 mg/dL, but body weight, antihypertensive medication, and ultrafiltration dose remained constant. In patients treated with calcitriol, an adequate reduction of iPTH levels was found (1,112 +/- 694 v 741 +/- 644 pg/mL; P < 0.05) without changes in values of serum ionized calcium (iCa++), phosphate, or hematocrit. Blood pressure (BP), cardiac output (CO), and total peripheral resistance (TPR) did not significantly change. After 15 weeks of treatment with calcitriol, M-mode echocardiograms showed pronounced reductions in interventricular wall thickness (13.9 +/- 3.6 v 12.8 +/- 3.10 mm; P = 0.01), left ventricular posterior wall thickness (12.5 +/- 2.4 v 11.3 +/- 1.8 mm; P < 0.05), and left ventricle mass index (LVMi; 178 +/- 73 v 155 +/- 61 g/m2; P < 0.01). However, in control patients, these changes were not found after the treatment period. In addition, sequential measurements of neurohormonal mediator levels in patients receiving calcitriol showed that plasma renin (18.5 +/- 12.7 v 12.3 +/- 11.0 pg/mL; P = 0.007), angiotensin II (AT II; 79.7 +/- 48.6 v 47.2 +/- 45.7 pg/mL; P = 0.001), and atrial natriuretic peptide (ANP; 16.6 +/- 9.7 v 12.2 +/- 4.4 pg/mL; P = 0.03) levels significantly decreased, whereas antidiuretic hormone (ADH), epinephrine, and norepinephrine levels did not change significantly. The percent change in LVMi associated with calcitriol therapy had a strong correlation with the percent change in iPTH (r = 0.52; P < 0.05) and AT II (r = 0.47; P < 0.05) levels. We conclude that the partial correction of SHPT with intravenous calcitriol causes a regression in myocardial hypertrophy without biochemical or hemodynamic changes, such as heart rate, BP, and TPR. The changes in plasma levels of iPTH and, secondarily, plasma levels of neurohormones (especially AT II) after calcitriol therapy may have a key role in attenuating ventricular hypertrophy in SHPT.

Metabolic abnormalities related to cardiovascular risk in primary hyperparathyroidism: effects of surgical treatment

OBJECTIVES

Untreated primary hyperarathyroidism (pHPT) is accompanied by an excessive morbidity in circulatory disorders, associated with blood pressure and diabetes. The aim of the present study was to further penetrate the impact of pHPT on glucose, urate, lipid and lipoprotein concentrations, known to be interrelated metabolic cardiovascular risk factors.

DESIGN

Longitudinal study of patients with pHPT before and 1 year after surgical treatment.

SETTING

Departments of Internal Medicine and Surgery, Lund University Hospital.

SUBJECTS

One hundred and seventeen consecutive patients with pHPT referred to surgical treatment. At presentation. 11 patients had previously diagnosed diabetes mellitus.

INTERVENTION

All patients were successfully operated for pHPT.

MAIN OUTCOME MEASURES

Fasting blood glucose and serum concentrations of cholesterol, triglyceride and urate were determined before and 1 year after surgery. The concentration of LDL- and HDL-cholesterol was separately analyzed in 21 cases. These data as well as the systolic and diastolic blood pressure were related to intact PTH and ionized calcium at presentation. Glomerular filtration was separately measured pre-operatively and related to the urate values.

RESULTS

While the mean value for glucose remained unchanged among 11 patients with previously diagnosed diabetes at presentation, a significant decrease of glucose from 5.03+/-0.13 to 4.71+/-0.08 mmol/L (P < 0.05) was found among patients without known diabetes. Out of these patients, eight had diabetic glucose values at presentation, decreasing from 8.35+/-0.54 to 5.10+/-0.35 mmol/L (P < 0.05), and 12 had glucose values indicating impaired glucose tolerance, decreasing from 5.94+/-0.06 to 5.10 +/-0.38 mmol/L (P < 0.05) after surgery. Total cholesterol and trigylceride concentrations were not changed. However, male patients had significantly lower triglyceride levels at follow-up, 1.16+/-0.09 mmol/L compared to 1.57+/-0.14 mmol/L before surgery (P < 0.05). Significantly lower triglyceride values were also found among patients with glucose values indicating impaired glucose tolerance at presentation. The LDL/HDL cholesterol ratio remained normal. The serum level of urate decreased in both male and female patients after surgery, and was positively correlated to the PTH and ionized calcium values and inversely correlated to renal function before treatment. There was no significant correlation between calcium or PTH and the other metabolic variables studied.