Autoimmune hypocalciuric hypercalcemia unresponsive to glucocorticoid therapy in a patient with blocking autoantibodies against the calcium-sensing receptor.

Context: Autoantibodies directed against the calcium-sensing receptor (CaSR) have been reported in several individuals with various autoimmune disorders and PTH-mediated hypercalcemia. Previously, glucocorticoid treatment has been shown to decrease the CaSR autoantibody titers and normalize the hypercalcemia in a patient with autoimmune hypocalciuric hypercalcemia (AHH).

Objective: The objective of the study was to evaluate a patient with AHH for the presence of blocking autoantibodies against the CaSR and to monitor her biochemical and serological responses to a trial of glucocorticoid therapy.