A pilot study on hypothalamo-pituitary-adrenocortical axis in primary hyperparathyroidism

Area of Science:

• Endocrinology
• Adrenal Physiology
• Calcium Homeostasis

Background:

• Parathormone (PTH) and calcium stimulate adrenal steroidogenesis in vitro.
• Structural similarity between PTH and adrenocorticotropin (ACTH) suggests potential interaction.
• In vivo human data on the PTH-calcium axis and adrenocortical function are lacking.

Purpose of the Study:

• To investigate the in vivo effect of the parathormone-calcium axis on adrenocortical function in humans.
• To assess cortisol dynamics and aldosterone levels in patients with primary hyperparathyroidism before and after parathyroidectomy.

Main Methods:

• Evaluated 10 primary hyperparathyroidism patients for cortisol dynamics (0800h/2000h plasma cortisol, insulin-induced hypoglycemia test, dexamethasone suppression test).
• Measured serum aldosterone pre- and post-parathyroidectomy.
• Repeated assessments 3 months after surgery.

Main Results:

• Half of patients showed loss of cortisol circadian rhythm; 40% had non-suppressible cortisol post-dexamethasone.
• All patients achieved peak cortisol response to hypoglycemia, with one-third showing exaggerated response.
• Cortisol abnormalities persisted in 40% post-surgery; aldosterone levels were within the upper normal range pre- and post-operatively.

Conclusions:

• Primary hyperparathyroidism is associated with inconsistent hypothalamo-pituitary-adrenocortical axis abnormalities.
• These abnormalities often do not resolve even 3 months after curative parathyroidectomy.