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Updated: Aug 15, 2026
Two Techniques to Create Hypoparathyroid Mice: Parathyroidectomy Using GFP Glands and Diphtheria-Toxin-Mediated Parathyroid Ablation
Published on: March 14, 2017
[Current function tests in hypoparathyroidism in children]
Insights
Measuring parathormone levels and their effects is crucial for diagnosing endocrine disorders. This study highlights differences in parathormone receptor sensitivity in pseudohypoparathyroidism and hypoparathyroidism.
Area of Science:
- Endocrinology
- Biochemistry
- Molecular Biology
Context:
- Direct measurement of circulating parathormone (PTH) and assessment of its renal effects via cyclic adenosine monophosphate (cAMP) assays are clinically available.
- Radio-immunoassay techniques for PTH utilize antisera with amino-terminal or carboxy-terminal specificity.
- Amino-terminal specificity reflects biologically active PTH, while carboxy-terminal specificity aids in detecting hormonal hypersecretion in pseudohypoparathyroidism due to fragment survival.
Purpose:
- To evaluate the sensitivity of renal and bone receptors to parathormone in children with pseudohypoparathyroidism and hypoparathyroidism.
- To compare the response to exogenous parathormone in pseudohypoparathyroid children versus normal and hypoparathyroid children.
Summary:
- The Ellsworth-Howard test, measuring plasma cAMP gradient after exogenous PTH injection, showed a complete absence of response in pseudohypoparathyroid children.
- Hypoparathyroid children exhibited a rapid cAMP response, with levels peaking at 10 minutes and increasing up to 20-fold baseline.
- Assessing bone receptor sensitivity through serum calcium and urinary hydroxyproline changes post-PTH injection proved difficult to interpret.
Impact:
- This research provides insights into the distinct mechanisms of parathormone resistance in pseudohypoparathyroidism.
- Understanding receptor sensitivity is vital for accurate diagnosis and management of parathormone-related disorders.
- The findings underscore the utility of cAMP assays in differentiating endocrine conditions affecting calcium homeostasis.
Abstract:
In clinical practice, we can now directly measure the level of circulating parathormone and we can also assess its impact on its renal effector by the assay of cyclic adenosine monophosphate. The radio-immunoassay of parathormone uses antisera with amino or carboxy terminal specificity. The preferential antibody has amino-terminal specificity in as much as the biological activity resides in this part of the hormone, so that the levels measured with this antibody reflect the levels of biologically active parathormone. However, the levels detected with antisera with carboxy-terminal specificity are much more discriminating in cases of hormonal hypersecretion in pseudohypoparathyroidism, because of the prolonged survival time of the fragments detected. The study of the sensitivity of the renal receptor to parathormone is based on the Ellsworth-Howard test. The plasma cyclic AMP gradient is measured following injection of exogenous parathormone. The results demonstrate a definite absence of response in the pseudohypoparathyroid children studied compared to normal and hypoparathyroid children. In children with hypoparathyroidism, the response is rapid with a maximal level of cyclic AMP obtained at 10 minutes. The gradient can be as much as 20 times the baseline level. The study of the sensitivity of the bone receptor to parathormone is based on classical tests whose results are difficult to evaluate, like changes in the serum calcium and the total urinary hydroxy-proline obtained after an injection of exogenous parathormone.
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