Vertebral fracture risk higher in chronic hypoparathyroidism: Study
Risk 55% higher than in general population
The risk of fractures in the vertebrae, the bones in the spine, was 55% higher in people with chronic hypoparathyroidism than in the general population, a nationwide study in Sweden found.
Conversely, the risk of femur (thighbone) fractures was 30% less common in the hypoparathyroidism group.
Chronic hypoparathyroidism patients were also diagnosed with osteoporosis (weak, brittle bones) more often, but their risk of having major fractures associated with osteoporosis was not higher.
“These findings suggest that while chronic [hypoparathyroidism] does not increase the overall risk of [major osteoporotic fractures], it affects bone health in ways that call for careful, individualized assessment and treatment,” the researchers wrote. Particularly, “increased awareness of osteoporosis and vertebral fracture risk in this population is warranted,” they wrote.
The study, “Increased risk of vertebral fractures and reduced risk of femur fractures in patients with chronic hypoparathyroidism: a nationwide cohort study in Sweden,” was published in the Journal of Bone and Mineral Research.
Assessing fracture risk
Hypoparathyroidism is characterized by low levels of the parathyroid hormone, PTH, which helps regulate calcium and phosphorus levels in the body. When PTH levels are too low, calcium levels become abnormally low, and phosphorus levels rise.
PTH plays a crucial role in regulating bone structure and remodeling. Chronic low levels of PTH can reduce the process of bone resorption and formation, leading to hypoparathyroidism symptoms like increased bone density and abnormalities in bone structure and strength.
The scientists set out to determine whether chronic hypoparathyroidism patients were at higher risk of fractures. They analyzed data from the Swedish National Patient Register, which includes hospital inpatient and outpatient data; the Swedish Prescribed Drug Register, which collects data on all prescription drugs in Sweden since July 2005; and the Swedish Total Population Register, which provides demographic data.
The team identified 1,915 people with chronic hypoparathyroidism treated with active vitamin D (which helps absorb calcium in the intestines) between 1997 and 2018, and 15,838 controls matched by sex, year of birth, and county of residence. In 71.8% of cases, hypoparathyroidism was the result of a surgical procedure.
Compared with controls, the group with chronic hypoparathyroidism was significantly older (mean age 53.9 vs. 50.2), had a shorter follow-up time (9.3 years vs. 10.4 years), and had both a higher proportion of women (76.1% vs. 73.3%) and of women taking hormone replacement therapy (10% vs. 5.6%).
Patients generally had more coexisting conditions, such as excessive levels of thyroid hormones, diabetes, cancer, and liver disease. Those with hypoparathyroidism had a median of 3.6 outpatient visits, 6.1 dispensations of vitamin D, and 3.7 dispensations of calcium supplements per year. Active vitamin D and calcium supplementation are the conventional treatment for hypoparathyroidism.
People with the disease were also 54% more likely to be diagnosed with osteoporosis, but 31% less likely to receive osteoporosis medications.
After adjusting for age, sex, and coexisting conditions, chronic hypoparathyroidism was not associated with a higher risk for osteoporosis-related major fractures — breaks of the hip, spine, forearm, or upper arm — even as these patients had a higher risk for vertebral fractures.
Vertebral fractures were more likely to occur in older patients, women, and those with epilepsy.
“DXA [a noninvasive imaging test to assess bone health] and vertebral imaging should be considered for patients with chronic [hypoparathyroidism], especially in those with additional clinical risk factors for osteoporosis, such as thyroid disease, loss of height, female gender, or older age, as vertebral fractures can be asymptomatic and do not always come to clinical attention,” the researchers wrote.
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