B-mode ultrasound assessment of carotid artery structural features in patients with normocalcaemic hyperparathyroidism.

Introduction: Normocalcaemic hyperparathyroidism is a condition first defined in 2008, characterized by normal serum calcium and high parathormone levels. Although normocalcaemic hyperparathyroidism is considered to have a milder clinical picture compared to asymptomatic primary hyperparathyroidism, recent studies have shown that it may be associated with osteoporosis, insulin resistance, metabolic syndrome, and cardiovascular risk factors. Considering that normocalcaemic hyperparathyroidism may pose a cardiovascular risk in the setting of carotid atherosclerosis, we sought to examine the structural features of the carotid artery in patients with normocalcaemic hyperparathyroidism compared to a control group.

Material and methods: After excluding patients with hypertension, diabetes, and dyslipidaemia (other factors contributing to atherosclerosis), 37 (32 females, 5 males) patients with normocalcaemic hyperparathyroidism with a mean age of 51.2 ± 8 (min: 32, max: 66) years and 40 controls (31 females, 9 males) with a mean age of 49.3 ± 7.5 (min: 34, max: 64) years with normal serum albumin-corrected calcium and parathyroid hormone levels were included in the study. Structural features of the carotid artery including intima-media thickness (mean and maximum), lumen diameter, and the presence of plaque were assessed using B-mode ultrasound.

Results: On ANCOVA analysis corrected for atherosclerotic factors (body mass index, waist circumference, fasting plasma glucose, serum cholesterol, lipid, and blood pressure), greater mean intima-media thickness was found in patients with normocalcaemic hyperparathyroidism than in controls (0.65 mm vs. 0.59 mm, respectively) (p = 0.023). Maximum carotid intima-media thickness was also greater in patients with normocalcaemic hyperparathyroidism compared to controls (0.80 mm vs. 0.75 mm, respectively) (p = 0.044). The study groups did not show a significant difference in lumen diameter and the presence of carotid plaque. In addition, a negative correlation was found between parathormone (PTH) level and lumen diameter.

Conclusion: The findings of this study show that as with asymptomatic primary hyperparathyroidism, normocalcaemic hyperparathyroidism may be associated with increased cardiovascular risk by predisposing to atherosclerosis.