Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 63

HPA axis activity increases with age. Both the morning cortisol peak and continuous cortisol secretion increase with age. The cortisol clearance rate decreases. The cortisol response to exogenously administered dexamethasone and ACTH is blunted in the elderly. Increased body fat composition causes more cortisol conversion from corticosterone. All of these changes result in an increased level of plasma cortisol. An excessive cortisol level causes muscle wasting, dysregulation of blood pressure and glucose, enhanced atherosclerosis, and susceptibility to infections. ACTH and aldosterone production are slightly decreased in the elderly.⁴²

Sympathetic activity increases with age. Plasma levels of norepinephrine increase, while receptor desensitization occurs. Subsequently, elderly people become prone to a delayed sympathetic response. Postural hypotension is one of the consequences.⁴³