Concentration of serum calcium is not correlated with symptoms or severity of primary hyperparathyroidism: An examination of 20,081 consecutive adults.

Background: Guidelines for operative treatment of primary hyperparathyroidism include calcium levels >1 mg/dL above normal. We sought to determine whether greater calcium concentrations were associated with increased symptoms or disease severity.

Methods: A retrospective review of a prospectively maintained database of adults undergoing parathyroidectomy for primary hyperparathyroidism, grouped according to greatest preoperative calcium level: those patients with calcium concentrations between 10.0 and 11.0 mg/dL and those with >11.0 mg/dL. We compared subjective symptoms and objective measures of disease severity.

Results: The review included 20,081 adults who were split nearly evenly between calcium concentrations between 10.0 and 11.0 (10,430, 51.9%) and those with >11.0 mg/dL (9,651, 48.1%). In both groups, an absence of symptoms related to primary hyperparathyroidism was uncommon (<5%). All subjective and objective measures of disease severity were nearly identical with no significant differences (percentages for calcium concentrations between 10.0 and 11.0 and those with >11.0 mg/dL, respectively), including fatigue (72% for both groups), heartburn (37% vs 34%), bone pain (50% vs 48%), sleep disturbances (68% vs 65%), osteoporosis (40% in both groups), kidney stones (21% vs 22%), chronic kidney disease with glomerular filtration rate <60 (29% vs 32%), and hypertension (50% vs 53%).

Conclusion: Serum calcium concentrations of greater than or less than 11 mg/dL are unrelated to symptoms and disease severity in primary hyperparathyroidism. There is no evidence to support a serum calcium threshold in parathyroidectomy guidelines.