Endocrine Abstracts

Objective: Primary hyperparathyroidism (PHPT) is associated with increased cardiovascular morbidity including hypertension with a prevalence ranging from 40 to 65%. The renin-angiotensin-aldosterone system (RAAS) is a key system in the regulation of sodium/potassium balance, volume homeostasis as well as blood pressure. There is increasing evidence of interactions between calcium and calcium-regulatory hormones with the RAAS. The aim of this study was to investigate the association between impaired calcium-phosphorus metabolism and the RAAS in PHPT patients.

Material and methods: We examined 57 patients with confirmed PHPT (48 women, 9 men, median age 49 years (Q1=39; Q3=56)). All patients underwent biochemical evaluation with monitoring blood pressure. Standardized blood sampling was performed before and in 3 days after surgical treatment for PHPT. The exclusion criteria were the glomerular filtration rate <75 ml/min/1.73 m², severe cardiovascular pathology, obesity, diabetes mellitus and treatment with drugs affected calcium balance.

Results: All cases presented symptomatic PHPT (median serum calcium level 2.73 mmol/l (Q1=2.61; Q3=2.98), PTH 122.7 pg/ml (Q1=94.0; Q3=203.0)). 38.6% of patients had mild and moderate hypertension that was corrected with antihypertensive therapy. Median levels of the RAAS components before and after surgery were: plasma renin activity (PRA) 0.42 (Q1=0.20; Q3=1.47) and 0.29 (Q1=0.08; Q3=1.16) ng/ml*h, aldosterone 108.2 (Q1=88.8; Q3=131.7) and 97.9 (Q1=77.7; Q3=126.8) pg/ml, angiotensin II 19.2 (Q1=16.3; Q3=21.1) and 20.2 (Q1=16.9; Q3=22.8) pg/ml respectively. No patients had deviations of serum aldosterone and angiotensin II levels, but slightly elevated PRA levels were defined in 10.5% of them. At the 3-rd day after surgery the biochemical evaluation revealed a significant decrease in PRA (P=0.019) and serum aldosterone levels (P=0.005). We found a significant positive correlation between intact PTH and PRA (P=0.009) as well as serum calcium and PRA levels (P=0.001) before parathyroidectomy. Serum calcium was also positively correlated with aldosterone (P=0.018) before surgery. In the early postoperative period PTH correlated only with angiotensin II level (P=0.012).

Conclusion: The study showed the significant changes of the RAAS activity after parathyroidectomy even in the early postoperative period. Further investigation with a long observation period is required to clarify these findings.