Short Acidification Test and Its Interpretation with Respect to Age

Renin-angiotensin-aldosterone system and the aging kidney

“…This hormone shows low serum levels as well as a reduced distal tubule response in the elderly. Senile lower levels of aldosterone have been observed either on an unrestricted salt KEYWORDS: aging • aldosterone • angiotensin • renin • senescence informahealthcare.comdiet or on salt restriction and walking settings [1,9,10]. The collecting duct is normally responsible for the final control of urinary sodium, potassium and proton excretion.…”

“…Although the distal tubule capability to handle sodium and potassium is significantly reduced in the elderly compared to these renal functions in the young, distal tubule acidification is slightly delayed but preserved in healthy old people in comparison with young people. This phenomenon has been attributed to the fact that ammonium ion excretion is less efficient or takes longer to reach its peak in response to an acute acid load in the elderly, though there is no absolute functional deficit in this tubular capability with senescence [5,8,10]. Finally, serum adrenocorticotropic hormone levels in healthy old people are the same as in young people, although its secretion rhythm varies [11].…”

Handling of water and electrolytes in the healthy old

“…37 Titratable acid elimination behaves similarly in the young and in the aged, 36,37 but in one study it was reported that it is higher in subjects above 60 years compared with the young. 39 There is almost a consensus that NH 4 + elimination is lower in the aged than in young subjects, except in one study 40 in which differences between young and aged people were not found. In this study, it was proven that the aged need more time to reach peak acid excretion (between 6 and 8 h) and that the same dose of ammonium chloride induces a greater decline in blood bicarbonate in the aged than in young individuals.…”

“…So far there are only five studies that have evaluated the response of the normal ageing kidney to a challenge with acid overload. [36][37][38][39][40] The kidney of healthy aged people is able to lower the urinary pH in response to acid overload to a value similar to that reached by healthy young adult subjects in response to the same stimulus. 39 Furthermore, in one study 36 it was reported that the fall in urinary pH was more intense in the aged, i.e.…”

Beyond chronic kidney disease: the diagnosis of Renal Disease in the Elderly as an unmet need. A position paper endorsed by Italian Society of Nephrology (SIN) and Italian Society of Geriatrics and Gerontology (SIGG)

“…This makes the elderly at special risk of dehydration or overhydration. At variance from water and electrolyte balance, renal acidification of the urine is well preserved in the aged: following an acid load, urinary pH may be lowered efficiently, and the same is also true for titratable acid elimination [19]. However, NH 4 elimination peaks later than in the adult in response to an acute acid load.…”