Related Experiment Videos
Deficient prolactin response to parathyroid hormone in hypocalcemic and normocalcemic pseudohypoparathyroidism
Insights
Children with pseudohypoparathyroidism (PHP) show a diminished prolactin (PRL) reserve, suggesting a pituitary receptor defect. This PRL deficiency may serve as an early marker for PHP diagnosis.
Area of Science:
- Endocrinology
- Pediatric Endocrinology
- Metabolic Bone Disease
Background:
- Pseudohypoparathyroidism type I (PHP) is a rare genetic disorder characterized by resistance to parathyroid hormone.
- Patients typically present with hypocalcemia, hyperphosphatemia, and skeletal abnormalities.
- The role of prolactin (PRL) in PHP has not been fully elucidated.
Purpose of the Study:
- To investigate the prolactin (PRL) response to parathyroid extract (PTE) in children with pseudohypoparathyroidism type I (PHP).
- To determine if PRL deficiency is a characteristic feature of PHP.
- To explore the potential of PRL deficiency as an early marker for PHP.
Main Methods:
- Infusion of parathyroid extract (PTE) (8 U/kg BW) in children with PHP, idiopathic hypoparathyroidism, and healthy controls.
- Prolonged PTE administration (six doses of 4 U/kg BW over 48 h) in PHP patients.
- Measurement of serum PRL levels before and after PTE administration.
Main Results:
- PTE infusion significantly increased serum PRL in healthy children and those with idiopathic hypoparathyroidism.
- No significant increase in serum PRL was observed in children with PHP following PTE infusion.
- Prolonged PTE administration did not alter the low serum PRL levels in PHP patients, indicating a diminished PRL reserve.
- One patient with normocalcemic PHP also exhibited PRL deficiency, suggesting it may be an early sign.
Conclusions:
- Patients with PHP exhibit an isolated diminished PRL reserve, distinct from other anterior pituitary functions.
- The findings suggest a pituitary receptor defect in PHP, in addition to previously known renal and bone resistance.
- Pituitary PRL deficiency may serve as an early diagnostic marker for pseudohypoparathyroidism.
Abstract:
The PRL response to the infusion of 8 U/kg BW parathyroid extract (PTE) was studied in three children with pseudohypoparathyroidism type I (PHP), three patients with idiopathic hypoparathyroidism, and eight epileptic children. PTE produced a clear-but increase of serum PRL in the epileptics and patients with idiopathic hypoparathyroidism, but not in the children with PHP. Prolonged PTE administration (six doses of 4 U/kg BW over 48 h) was also without effect on the low serum PRL levels in the three patients with PHP. These patients exhibited an isolated diminished PRL reserve to other potent PRL stimuli in the presence of intact function of the remainder of the anterior pituitary. The data suggest a pituitary receptor defect in patients with PHP in addition to disturbed renal and bone responses. One patient with normocalcemic PHP, seeming to be in the early stage of the disease, demonstrated the same distinct PRL deficiency as the other two patients with manifest PHP. This suggests that the pituitary receptor defect may be an early sign and marker of PHP.