Abstract
The “dawn phenomenon” is described in patients with insulin dependent diabetes (IDD) and normal subjects characterized by abrupt increases in plasma glucose (G) levels and/or insulin (I) requirements between 5 and 9 a.m. Suppression of cortisol by metyrapone or ACTH by dexamethasone has failed to abolish the “dawn phenomenon” in IDD so the ACTH-adrenal axis has been felt not to play a role. We have tested this hypothesis in patients with 21-hydroxylasc CAH whose ACTH secretion is altered by receiving their usual hs cortisol dosage.
Seven patients, m age 2(1.2 ± 1.7 y, M/F:4/3, m hydrocortisone dose 16.7 ± 4.7 mg/m2/day, were studied. Levels of plasma G, I, cortisol, growth hormone were measured q 20 min, ACTH q h.
After 0500h plasma glucose dropped significantly (p<0.01) though plasma insulin concentration dropped significantly in all but one, while ACTH levels increased and cortisol dropped then rose. Other hormones were not different before and after 0500h All had normal GTT's. We conclude that a reversed “dawn phenomenon” occurs in treated patients with CAH, suggesting that this phenomenon is an ACTH - cortisol dependent event.
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Arslnina, S., Starceski, P., Becker, D. et al. REVRESED CHRONOBIOLOGY OF THE “DAWN PHENOMENON” IN ADRENAL HEYPERPLASTA: RESURGENCE OF THE ACTH-ADRENAL AXIS. Pediatr Res 21 (Suppl 4), 339 (1987). https://doi.org/10.1203/00006450-198704010-01031
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DOI: https://doi.org/10.1203/00006450-198704010-01031