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Abnormal pentagastrin response in a patient with pseudohypoparathyroidism
O Zwermann1, B Piepkorn, M Engelbach
1Clinic for Internal Medicine, Endocrinology and Metabolism, University of Mainz, Germany. Zwermann@med1.ukl.uni-freiburg.de
Summary
This study reports a rare case of pseudohypoparathyroidism type I (PHP) with hypercalcitoninaemia. Chronic hypocalcaemia may explain the abnormal pentagastrin test, suggesting careful observation in PHP patients.
Area of Science:
- Endocrinology
- Metabolic Disorders
- Clinical Case Study
Background:
- Pseudohypoparathyroidism type I (PHP) is a rare genetic disorder characterized by resistance to parathyroid hormone, leading to hypocalcaemia.
- Hypercalcitoninaemia, elevated calcitonin levels, is not a typical feature of PHP.
- This report details a unique case highlighting the interplay between these conditions.
Observation:
- A 25-year-old female presented with recurrent hypocalcaemia, paraesthesias, and muscle cramps.
- Laboratory findings revealed hypocalcaemia, hyperphosphataemia, and markedly elevated parathyroid hormone (PTH) levels, confirming PHP type I.
- She also exhibited hypercalcitoninaemia and an exaggerated calcitonin response to pentagastrin stimulation, atypical for PHP.
Findings:
- The patient had no signs of Albright hereditary osteodystrophy (AHO), normal mental status, and no family history of endocrine disease.
- Delayed pubertal development and hypothyroidism were also noted.
- Despite the abnormal pentagastrin test, suggestive of medullary thyroid carcinoma, no malignancy was detected during a one-year follow-up.
Implications:
- The findings suggest that chronic hypocalcaemia in PHP may cause a pathological pentagastrin test response.
- The specificity of the pentagastrin test may be diminished in patients with PHP.
- A cautious observational approach is recommended when interpreting abnormal pentagastrin test results in the context of PHP.