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Pseudohypoparathyroidism Ia and hypercalcitoninemia
V Vlaeminck-Guillem1, M D'herbomez, P Pigny
1Service de Médecine Interne et Endocrinologie, CHU de Lille, 59037 Lille, France. virginie.vlaeminck@wanadoo.fr
The Journal of Clinical Endocrinology and Metabolism
|July 10, 2001
Summary
Pseudohypoparathyroidism Ia (PHP Ia) patients show higher calcitonin levels and impaired calcitonin response, suggesting a distinct cause of hypercalcitoninemia. This highlights potential C cell dysfunction in PHP Ia.
Area of Science:
- Endocrinology
- Genetics
- Metabolic Disorders
Background:
- Pseudohypoparathyroidism Ia (PHP Ia) involves resistance to parathyroid hormone (PTH) due to G protein alpha-subunit deficiency.
- C cell dysfunction is not well-characterized in PHP Ia.
Purpose of the Study:
- To investigate calcitonin levels and response in patients with PHP Ia.
- To determine if PHP Ia is an independent cause of hypercalcitoninemia and C cell dysfunction.
Main Methods:
- Calcitonin assays were performed on six PHP Ia patients and four pseudopseudohypoparathyroidism patients.
- Pentagastrin infusion tests were conducted to assess calcitonin response and plasma cAMP levels.
- Genomic screening for RET protooncogene mutations was performed.
Main Results:
- PHP Ia patients exhibited significantly higher basal calcitonin levels compared to controls.
- Five out of six PHP Ia patients showed elevated calcitonin levels after pentagastrin infusion.
- Calcitonin infusion failed to increase plasma cAMP in PHP Ia patients, indicating impaired calcitonin action.
Conclusions:
- PHP Ia is associated with hypercalcitoninemia and impaired calcitonin response.
- C cell dysfunction appears to be an independent feature of PHP Ia.
- The findings suggest PHP Ia as a distinct etiology for hypercalcitoninemia.