Miñambres I, Corcoy R, Weetman AP, et al. - In the present study, the researchers sought to describe two patients in whom the presence of autoimmune hypocalciuric hypercalcemia (AHH) was suspected and to evaluate the patients for the presence of calcium-sensing receptor (CaSR) antibodies. CaSR antibodies were identified and characterized by immunoprecipitation assays, CaSR peptide ELISAs, and functional assays based on the calcium-stimulated accumulation of inositol-1-phosphate in a mammalian cell line expressing the CaSR. According to results, both of the patients had an acquired form of hypocalciuric hypercalcemia. Patients with an acquired biochemical pattern of PTH-dependant hypocalciuric hypercalcemia, particularly those with other concomitant autoimmune diseases, should be suspected of having AHH. Diagnosis by detecting CaSR antibodies can help improve the characterization of this condition, which is probably underreported.