Rare Causes of Hypercalcemia: 2021 Update

Area of Science:

• Endocrinology
• Calcium Metabolism

Background:

• Primary hyperparathyroidism and malignancy account for 90% of hypercalcemia cases.
• Uncommon conditions require consideration when typical etiologies are absent.
• This review updates a 2005 clinical synopsis on rare hypercalcemia causes.

Purpose of the Study:

• To provide an updated synopsis of rare causes of hypercalcemia.
• To extend the observations of prior reviews on hypercalcemia pathophysiology.
• To highlight the growing understanding of unusual hypercalcemia etiologies.

Main Methods:

• Comprehensive PubMed search using terms "hypercalcemia" and "etiology."
• Examination of references in identified case reports.
• Categorization of reports by adult vs. pediatric and by etiology.

Main Results:

• Identified rare associations between hypercalcemia and unusual conditions.
• Some reports lacked definitive etiology, with likely causes discussed.
• Growing understanding of the breadth of unusual hypercalcemia causes.

Conclusions:

• When hypercalcemia etiology is elusive, focus on mechanism and prior cases is key.
• Continued investigation into human calcium metabolism is needed.
• Rare and unknown mechanisms of hypercalcemia require further study.