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Differential diagnosis of hypoparathyroid disorders during childhood
Insights
Measuring plasma cyclic AMP after parathyroid hormone infusion effectively diagnoses hypoparathyroid disorders. This method differentiates between pseudohypoparathyroidism and idiopathic hypoparathyroidism in children.
Area of Science:
- Pediatric Endocrinology
- Biochemical Diagnostics
- Hormone Regulation
Background:
- Hypoparathyroidism encompasses idiopathic and pseudohypoparathyroidism, requiring accurate differential diagnosis.
- Parathyroid hormone (PTH) plays a crucial role in calcium homeostasis.
- Adenosine 3', 5' monophosphate (cyclic AMP) is a key intracellular second messenger in PTH signaling.
Purpose of the Study:
- To evaluate the diagnostic utility of plasma cyclic AMP (cAMP) response to parathyroid hormone infusion in differentiating hypoparathyroid disorders.
- To compare cAMP levels in normal children versus those with idiopathic hypoparathyroidism and pseudohypoparathyroidism.
Main Methods:
- Infusion of parathyroid hormone in 10 normal children, 5 with idiopathic hypoparathyroidism, and 3 with pseudohypoparathyroidism.
- Measurement of plasma cyclic AMP levels before and 5 minutes after PTH infusion.
- Analysis of plasma cyclic AMP concentration changes in response to PTH stimulation.
Main Results:
- Normal children exhibited a 10-fold increase in plasma cyclic AMP post-PTH infusion.
- Children with idiopathic hypoparathyroidism showed an 18-fold increase in plasma cyclic AMP.
- Patients with pseudohypoparathyroidism demonstrated no significant increase in plasma cyclic AMP after PTH infusion.
Conclusions:
- Plasma cyclic AMP measurement following PTH infusion is a reliable diagnostic tool.
- This method effectively distinguishes between idiopathic hypoparathyroidism and pseudohypoparathyroidism.
- The study highlights a practical biochemical approach for diagnosing hypoparathyroid conditions.
Abstract:
Changes in the plasma and urinary adenosine 3', 5' monophosphate (cyclic AMP) levels on infusion of parathyroid hormone were studied in 10 normal children, 5 children with idiopathic hypoparathyroidism, and 3 children with pseudohypoparathyroidism. In normal children the plasma concentration of cyclic AMP ranges from 18.0 to 68.0 pmoles/ml under basal conditions, and increases to a peak of about 10-fold the basal level 5 min after infusion of parathyroid hormone. Infusion of parathyroid hormone caused no increase in plasma cyclic AMP in patients with pseudohypoparathyroidism but about 18-fold increase in those with idiopathic hypoparathyroidism. The measurement of plasma cyclic AMP before and 5 min after infusion of parathyroid hormone is concluded to be a single and effective method for differential diagnosis of hypoparathyroid disorders.