Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol 51, Issue 1 B91-B99, Copyright © 1996 by The Gerontological Society of America
Age and systemic acid-base equilibrium: analysis of published data
L Frassetto and A Sebastian
Department of Medicine, University of California, San Francisco.
To investigate whether systemic acid-base equilibrium changes with aging in
normal adult humans, we reviewed published articles reporting the acid-base
composition of arterial, arterialized venous, or capillary blood in
age-identified healthy subjects. We extracted or calculated blood hydrogen
ion concentration ([H+]), plasma bicarbonate concentration ([HCO3(-)]),
blood PCO2, and age, and computed a total of 61 age-group means,
distributed among eight 10-year intervals from age 20 to 100 years. Using
linear regression analysis, we found that with increasing age, there is a
significant increase in the steady-state blood [H+] (p < .001), and
reduction in steady-state plasma [HCO3(-)] (p < .001), indicative of a
progressively worsening low-level metabolic acidosis. Blood PCO2 decreased
with age (p < .05), in keeping with the expected respiratory adaptation
to metabolic acidosis. Such age-related increasing metabolic acidosis may
reflect in part the normal decline of renal function with increasing age.
The role of age-related metabolic acidosis in the pathogenesis of the
degenerative diseases of aging warrants consideration.
