Adrenomedullin concentrations are elevated in plasma of patients with primary hyperparathyroidism

The aim of the study was to evaluate plasma adrenomedullin (AM) concentration in primary hyperparathyroidism (PHP) and its effect on the regulation of blood pressure. Forty-one patients with PHP (25 normotensive and 16 hypertensive), and 31 healthy subjects (HS) were included in the study. As expected the total and ionized calcium and i-PTH serum levels were significantly higher in patients with PHP than in HS (P <.001). No significant difference was found in calcium-phosphorus metabolism parameters between normotensive and hypertensive PHP patients. Serum i-PTH levels correlated positively with systolic blood pressure (SBP) (r = 0.510; P <.02), diastolic blood pressure (DBP) (r = 0.586; P <.01) and heart rate (HR) (r = 0.486; P <.043) only in hypertensive PHP patients. Overall, mean plasma AM concentrations were significantly higher in PHP patients (16.1 +/- 7.9 pg/mL) than in HS (11.3 +/- 4.8 pg/mL) (P <.003) and correlated with i-PTH (r = 0.430; P <.005). However, in hypertensive PHP patients plasma AM levels (22.5 +/- 4.7 pg/mL) were higher than in normotensive PHP patients (11.6 +/- 1.8 pg/mL) (P <.001) and correlated with DBP (r = 0.902, P <.0029). In HS no correlation was found between plasma AM values and biohumoral, hormonal, or hemodynamic parameters. In conclusion, we demonstrated that in patients with PHP, plasma AM concentrations are increased and correlate with i-PTH and blood pressure values. We suggest that increased AM levels could be a compensatory factor in the defence mechanism against further blood pressure elevation.