Hypoparathyroidism Increases Blood Pressure and Blood Vessel Stiffness, Study Shows

People with hypoparathyrodism have significantly higher blood pressure and stiffness of blood arteries — two known risk factors for cardiovascular disease — than their healthy peers, a Turkish study shows.

The research also highlighted that older age and abnormally high levels of phosphorus were associated with increased arterial stiffness.

Based on those findings, researchers recommend that all hypoparathyroidism patients should be monitored closely for phosphorus levels and cardiovascular disease.

The study, “Central and peripheral blood pressures and arterial stiffness increase in hypoparathyroidism,” was published in the journal Archives of Endocrinology and Metabolism.

Hypoparathyroidism is caused by abnormally low levels of the parathyroid hormone (PTH), which may result from a surgery in the neck region — where the parathyroid glands, responsible for PTH production, are located — or have other causes.

PTH deficiency results in low levels of calcium (hypocalcemia) and high levels of phosphorus (hyperphosphatemia) in the blood. This can lead to the accumulation of calcium (calcifications) throughout the body, including in the cardiovascular system.

Increasing evidence suggests that changes in PTH, calcium, and phosphorus levels affect cardiovascular health. Also, an association between hypoparathyroidism and a higher risk of cardiovascular disease is generally accepted for patients whose disease is not associated with neck surgery.

However, there are conflicting results when it comes to cardiovascular disease risk in people with surgery-associated hypoparathyroidism.

Researchers in Turkey assessed the levels of several cardiovascular parameters — in particular arterial stiffness, which is considered an independent risk factor of cardiovascular disease — in 42 hypoparathyroidism patients and 60 healthy participants with no history of parathyroid gland disease.

Hypoparathyroidism was associated with a neck surgery in 33 patients (78.6%), with an unknown cause in eight (19%), and with a disorder called autoimmune polyglandular syndrome in one patient (2.4%).

Controls had similar age, gender, and body mass index as patients. All participants were adults, had no chronic disease, and did not smoke.

Arterial stiffness was measured through a validated, non-invasive method called pulse wave analysis (PWA) in the brachial artery just above the elbow. PWA measures pulse wave velocity (PWV), the speed at which a pulse wave passes through an artery, with faster pulses reflecting higher stiffness, and consequently higher risk of cardiovascular disease.

The team also analyzed other cardiovascular parameters, including blood pressure and cardiac output.

Results showed that, as expected, hypoparathyroidism patients had significantly lower levels of PTH and calcium, and significantly higher phosphorus levels in the blood than unaffected individuals.

Notably, these patients showed significantly higher values in several blood pressure measures and in PWV (arterial stiffness), compared with healthy participants.

In addition, lower levels of PTH and calcium and higher levels of phosphorus in the blood were significantly associated with increased blood pressure and arterial stiffness among all participants.

Further analyses identified older age and higher levels of phosphorus as independent predictors of high arterial stiffness.

The researchers said the association of phosphorus levels with blood pressure and arterial stiffness is consistent with calcification of the cardiovascular system due to hyperphosphatemia.

Overall, these findings indicate that hypoparathyroidism, regardless of its association with surgery, causes an increase in blood pressure and arterial stiffness, with a consequent increased risk of cardiovascular disease.

“The patients diagnosed with hypoparathyroidism should be closely monitored and treatment planning should include to prevent the patients from hyperphosphatemia,” the researchers wrote.