Parathyroid Hormone Resistance and Autoantibodies to the PTH1 Receptor

This study describes two cases of acquired parathyroid hormone (PTH) resistance due to autoantibodies targeting the PTH type 1 receptor (PTH1R), which block PTH binding and signaling. Both patients presented with severe hypocalcemia, hyperphosphatemia, and markedly elevated PTH levels, alongside other autoimmune manifestations. In vitro assays confirmed the presence of PTH1R-blocking IgG autoantibodies, which were absent in patients with other renal or autoimmune disorders. The findings highlight a novel autoimmune mechanism for PTH resistance, distinct from congenital forms, and suggest potential therapeutic avenues such as immunosuppressive therapies.

This study describes two cases of acquired parathyroid hormone (PTH) resistance due to autoantibodies targeting the PTH type 1 receptor (PTH1R), which block PTH binding and signaling. Both patients presented with severe hypocalcemia, hyperphosphatemia, and markedly elevated PTH levels, alongside other autoimmune manifestations. In vitro assays confirmed the presence of PTH1R-blocking IgG autoantibodies, which were absent in patients with other renal or autoimmune disorders. The findings highlight a novel autoimmune mechanism for PTH resistance, distinct from congenital forms, and suggest potential therapeutic avenues such as immunosuppressive therapies.