This article is more than 5 years old. Information may no longer be current.
Parathyroid hormone levels not associated with mortality in older women
Click Here to Manage Email Alerts
Parathyroid hormone levels in older women remained within the normal reference range as women aged, even with parathyroid hormone increases of up to 50% above baseline, researchers in Sweden reported.
“Vitamin D is the major factor determining [parathyroid hormone] levels in healthy adults, and furthermore, both [parathyroid hormone] and vitamin D are closely linked to kidney function; [parathyroid hormone] increases as kidney function declines while vitamin D decreases,” David Buchebner, MD, of the department of clinical science at Lund University in Malmö, Sweden, and colleagues wrote. “Given this relationship, chronic kidney disease and vitamin D insufficiency are common with increasing age, and both are associated with increased mortality in older women. ... Our understanding of the age-related changes in serum [parathyroid hormone] levels, how to interpret [parathyroid hormone] values overall, the relationship to standard reference ranges and what can be considered normal or abnormal in older or very old women is clearly limited and warrants further investigation.”
The researchers conducted a prospective, population-based, longitudinal cohort study of women from the Malmö Osteoporosis Prospective Risk Assessment cohort (n = 1,044). All women were aged 75 years at baseline and were followed for up to 15 years. Researchers performed reassessments at age 80 (n = 715) and 85 years (n = 382). The main outcomes were measurements of parathyroid hormone levels, vitamin D, calcium, phosphate and estimated glomerular filtration rate, as well as associations between parathyroid hormone levels and mortality.
Most patients aged 75 years (88%; n = 877) had parathyroid hormone levels within the normal reference range (< 6.9 pmol/L), the researchers reported. Mean parathyroid hormone levels increased by age 80 years, but 74% of patients (n = 512) were still in the normal reference range. It was only when parathyroid hormone increases above baseline exceeded 50% that levels were elevated beyond the normal reference range, Buchebner and colleagues wrote.
These increases yielded a mean parathyroid hormone level of 7.1 pmol/L at 5 years of follow-up, with lower eGFRs (56 mL/min/1.73 m2 vs. 61 mL/min/1.73 m2; P = .002); at 10 years of follow-up, mean parathyroid hormone level was 9.5 pmol/L with a continuing decline in kidney function (42 mL/min/1.73 m2 vs. 54 mL/min/1.73 m2; P = .001), despite similar levels of 25-hydroxyvitamin D, according to Buchebner and colleagues. After adjustment, the researchers reported no association between parathyroid hormone levels at age 80 years and mortality.
“In this population-based, longitudinal observational study of 75-year-old women, [parathyroid hormone] increased with advancing age,” the researchers wrote. “The study provided new insights to [parathyroid hormone] profiles and its assumed association with mortality in a very old population. Elevated [parathyroid hormone] was not independently associated with mortality, but rather a consequence of impaired health, possibly mirroring a state of increased frailty.” – by Andy Polhamus
Disclosure: The researchers report no relevant financial disclosures.
Perspective
Back to Top
This is a unique, long-term population-based observational follow-up study designed to look at changes in parathyroid hormone levels over time as well as the potential association between parathyroid hormone levels and mortality. The authors examined data from 1,044 community-dwelling women living in Sweden who were followed prospectively; 382 women were available for follow up at the study's end. At study entry, women were 75 years old, and they were followed to age 85 years. Most were in good health, and 88% had a parathyroid hormone level in the normal range. The natural history of changes in parathyroid hormone levels in women in this age range is not clear, but this study adds to our knowledge.
Despite a modest increase in levels, the vast majority of subjects maintained parathyroid hormone values in the normal range throughout the study. In addition, parathyroid hormone levels were not associated with increased mortality. Elevated levels have been associated with mortality and metabolic syndrome, especially in men. In this study, however, higher parathyroid hormone levels did not correlate with mortality. Parathyroid hormone level did show an inverse correlation with kidney function and vitamin D level, as expected. This was not a study of women with hyperparathyroidism with hypercalcemia; most were in the normal range for parathyroid hormone. Parathyroid hormone levels rose in an inverse relationship to eGFR, but most subjects had a normal parathyroid hormone level even at age 85 years.
This study showed that parathyroid hormone level in the normal range was not independently associated with mortality in women, even when the level rose by 50%. Elevations in parathyroid hormone in this cohort seemed be a marker of impaired health and not a cause. It remains unclear why elevations in parathyroid hormone levels are associated with increased mortality in men. It is possible that the differences are sex-specific.
Disclosure: Lenhard reports no relevant financial disclosures.
Click Here to Manage Email Alerts