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Parathyroid hormone level fails to predict kidney stones, fracture risk in primary hyperparathyroidism
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In patients with primary hyperparathyroidism, parathyroid hormone level is not associated with incidence of renal stones, low bone mineral density or mortality, suggesting other factors may play a role in predicting adverse outcomes, according to findings from a retrospective cohort study.
“This research suggests that perhaps we can begin to stratify who requires abdominal imaging in the context of primary hyperparathyroidism, given the low likelihood of detecting asymptomatic renal stones,” Fraser W. Gibb, MBChB, PhD, FRCP Edin, consultant physician and honorary clinical senior lecturer at the Edinburgh Centre for Endocrinology and Diabetes, United Kingdom, told Endocrine Today. “In our cohort, low BMD was not largely associated with the degree of parathyroid hormone elevation. Better predictors of fracture in primary hyperparathyroidism are required. Reassuringly, parathyroid hormone does not appear to be independently associated with mortality.”
Gibb and colleagues analyzed data from 611 patients presenting with a new diagnosis of primary hyperparathyroidism at the Royal Infirmary of Edinburgh and Western General Hospital, U.K., between 2006 and 2014, identified via a clinic database. Mortality data were obtained via patient record and national registry data. Researchers assessed levels of calcium (plasma and urine), phosphate, magnesium, alkaline phosphatase and creatinine. Renal imaging results (X-ray, renal tract ultrasound or CT kidney-ureter-bladder imaging; n = 441) and bone density measurements via DXA (n = 461) were obtained from electronic patient records. Researchers used logistic regression analysis to determine independent predictors of nephrolithiasis and osteoporosis and Cox proportional hazards models to determine independent predictors of mortality.
Within the cohort, 13.9% of patients had nephrolithiasis, with most presenting with already documented stone disease (9.7%), according to researchers, whereas only 4.7% of asymptomatic patients screened for renal stones had calculi identified. Researchers found that younger age (P < .001) and male sex (P = .003) were the only independent predictors of nephrolithiasis.
Among patients with DXA measurements, 48.4% had osteoporosis. Researchers found that older age (P < .001), lower BMI (P = .002) and lower creatinine level (P = .006) were independently associated with a diagnosis of osteoporosis. Higher parathyroid hormone level was independently associated with lower z score at the hip (P = .009), but not at other sites, according to researchers. Calcium level was not associated with lower z score.
Mortality in primary hyperparathyroidism was associated with older age (P < .008), social deprivation (P = .028) and adjusted calcium level (P = .009), but was not independently associated with parathyroid hormone at diagnosis, according to researchers.
The researchers noted that, based on the study findings, “less aggressive” case findings should be recommended for low-risk patients with respect to renal stones — specifically older women with modest hypercalcemia. Additionally, they wrote, a large-scale assessment of the predictive value of new modalities, such as trabecular bone score and quantitative CT, is necessary in patients with primary hyperparathyroidism.
“A randomized controlled trial of surgical intervention vs. observation in people with asymptomatic primary hyperparathyroidism, powered for cardiovascular outcomes and fracture incidence, is needed,” Gibb said.
In a nested, case-control study published in The Journal of Clinical Endocrinology & Metabolism in June and reported by Endocrine Today, researchers found that patients with primary hyperparathyroidism have a high prevalence of renal calcifications that are typically linked to the severity of the disease. Patients with and without renal calcifications (n = 617) did not differ in age or sex, but patients with renal calcifications had a slightly lower BMI vs. those without calcifications, as well as increased levels of 24-hour urinary calcium and calcium ions. In that study, the use of 24-hour urinary calcium as a predictor of nephrolithiasis was found to have poor diagnostic accuracy, with an area under the curve below 0.6 (95% CI, 0.53-0.67), according to researchers. – by Regina Schaffer
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Fraser W. Gibb, MBChB, PhD, FRCP Edin, can be reached at the Edinburgh Centre for Endocrinology and Diabetes, Royal Infirmary of Edinburgh, Edinburgh, EH16 4SA, United Kingdom; email: fraser.gibb@ed.ac.uk.
Disclosures: The authors report no relevant financial disclosures.
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