ESPE Abstracts

Objective: To evaluate the correlation of GNAS gene mutation in clinically diagnosed pseudohypoparathyroidism patients and to examine accompanying hormonal abnormalities and phenotypic features.

Materials and Methods: Our study group consisted of 6 patients who were followed and treated with the diagnosis of pseudohypoparathyroidism in our clinic. Calcium (Ca), phosphorus (P), and parathyroid hormone (PTH) levels were evaluated at the time of diagnosis and after treatment. Treatment included calcium supplementation, cholecalciferol, and its active form, dihydrocholecalciferol. GNAS gene mutation was analyzed. Accompanying hormonal abnormalities, heterotopic osteodystrophies, and phenotypic features were evaluated.

Results: After the initiated treatment, phosphorus, calcium, and PTH values reached normal ranges. GNAS positivity was detected in half of the 6 patients tested for GNAS gene mutation, while the analyses of the other patients are still pending. All patients with GNAS positivity exhibited heterotopic ossification and/or Albright Hereditary Osteodystrophy (AHO) phenotypic features, and two patients had concurrent hypothyroidism. Among the three patients whose GNAS mutation analysis is still pending, one had hypothyroidism, two had heterotopic ossification, and again, two had AHO phenotype.

Conclusion: Hypothyroidism may be the first clinical sign of PHP. While congenital hypothyroidism is detected through neonatal screening, PHP is usually diagnosed when hypocalcemia and elevated PTH levels are present. It is often identified as a condition emerging in early childhood. In Type 1 PHP, there is resistance to PTH as well as to growth hormone, TSH, and GnRH, whereas in Type 2 PHP, only resistance to PTH is observed. Therefore, in addition to PHP treatment and follow-up, clinical monitoring for other potential hormone resistances is recommended in diagnosed patients.