Calcium Disorders in Rheumatic Diseases: An Overlooked Problem With Major Clinical Implications

Rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), spondyloarthritis, calcium pyrophosphate deposition disease, and the therapies used to treat them, particularly disease-modifying antirheumatic drugs, exemplify clinical contexts where calcium homeostasis has underappreciated relevance. Calcium balance is central to skeletal integrity, immune signalling, and multisystem function in rheumatic diseases, yet it is frequently overshadowed by inflammatory priorities. Despite growing evidence linking calcium disorders to morbidity, integration into routine rheumatology care remains limited, representing a persistent clinical gap. The objective of this review is to synthesize current knowledge on the spectrum, mechanisms, manifestations, and management of calcium disorders in rheumatic diseases. A narrative review was conducted using PubMed, Scopus, and Web of Science, covering literature published between 2015 and 2025, including original studies and reviews. Chronic inflammation, therapeutic exposures, endocrine disruption, and renal involvement collectively drive hypocalcemia, hypercalcemia, secondary hyperparathyroidism, and crystal deposition disorders. These abnormalities contribute to skeletal fragility, renal complications, cardiovascular calcification, and diagnostic uncertainty. Integrating calcium assessment into rheumatologic practice has important implications for risk stratification, individualized therapy, and the prevention of long-term complications. Calcium disorders should be recognized as integral components of rheumatic disease biology rather than incidental comorbidities. The systematic, multidisciplinary integration of calcium homeostasis into rheumatology care can meaningfully improve patient outcomes.