Todorova–Koteva K et al. – The results show for the first time the implementation of a simple new diagnostic tool designed to check for parathyroid hormone resistance. This new test has already shown to be useful in few occasions at the institution. However, larger populations should be tested before implementation of such test is considered a standard of care.

• The test consists of a subcutaneous injection of commercially available recombinant parathyroid hormone and concomitant measurement of cyclic adenosine monophosphate in urine.
• The authors implemented the test in two patients with recalcitrant hypocalcemia and a healthy control.

• The test unequivocally demonstrated parathyroid hormone resistance in both patients.
• One of the patients had phenotypically evident pseudohypoparathyroidism type-1a hence parathyroid hormone resistant was suspected.
• The other patient with non-phenotypically evident disease, also showed parathyroid hormone resistance and was later demonstrated to have pseudohypoparathyroidism type-1b at the genomic level and confirmed to be of familial type.