Growth hormone (GH) secretion in primary adrenal insufficiency: Effects of cortisol withdrawal and patterned replacement on GH pulsatility and circadian rhythmicity

Ariel L. Barkan, Roberta DeMott-Friberg, Mary H. Samuels

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

We studied the effects of cortisol withdrawal and patterned replacement upon spontaneous GH secretion and circadian rhythmicity in 7 patients with Addison's disease. Hydrocortisone was administered in physiological daily total dosages, and all resulting plasma cortisol values were 2-15 μg/dl. It was given in 3 pulsatile modes: simulating "physiological" rhythm, "reverse" diurnal rhythmicity and "continuous" pulsatility. All modes of cortisol administration increased mean 24h, GH pulse amplitude and interpulse GH levels. During saline infusions circadian GH rhythmicity was preserved, with GH being at its highest between 2400-0400 h. Administration of hydrocortisone in any mode did not modify circadian GH rhythmicity. We conclude: Cortisol replacement in physiological daily doses increases GH output in patients with Addison's disease by augmenting GH pulse amplitude and interpulse levels. This is likely due to the attenuation of hypothalamic somatostatin (SRIF) secretion by physiologic levels of cortisol. By inference, it implies that cortisol deficiency leads to diminution of GH output with low GH pulse amplitude, likely as a result of an augmented hypothalamic somatostatin secretion. However, circadian rhythmicity of GH secretion is glucocorticoid-independent.

Original languageEnglish (US)
Article number324056
Pages (from-to)175-179
Number of pages5
JournalPituitary
Volume3
Issue number3
DOIs
StatePublished - Jan 1 2000

Keywords

  • Addison's disease
  • Diurnal rhythm
  • Hydrocortisone
  • Somatotropin

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

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