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Renal amino acid excretion and aging
H Nádvorníková1, O Schück, V Teplan
1Institute for Clinical and Experimental Medicine, Prague.
Physiological Research
|January 1, 1991
Summary
Elderly individuals show increased fractional excretion of certain amino acids due to reduced tubular reabsorption, potentially linked to changes in sodium transport.
Area of Science:
- Nephrology
- Geriatric Medicine
- Biochemistry
Background:
- Amino acid metabolism and renal handling are crucial for overall health.
- Age-related changes in kidney function can impact nutrient reabsorption.
- Understanding these changes is vital for geriatric health and nutritional management.
Purpose of the Study:
- To investigate age-related alterations in urinary amino acid excretion and serum concentrations.
- To determine the mechanisms behind changes in renal amino acid handling in the elderly.
- To explore the relationship between tubular sodium transport and amino acid reabsorption.
Main Methods:
- Studied 62 healthy individuals aged 15-70 years.
- Measured urinary amino acid excretion and serum concentrations.
- Assessed glomerular filtration rate (GFR) and fractional excretion (FE) of amino acids and sodium (FENa).
Main Results:
- Elderly subjects (61-70 years) exhibited significantly increased fractional excretion (FE) of Cysteine (CYS), Valine (VAL), Methionine (MET), Isoleucine (ILE), and Leucine (LEU).
- Serum concentrations of these amino acids remained unchanged, while GFR decreased in the elderly.
- A significant correlation was observed between fractional sodium excretion (FENa) and the FE of most amino acids.
Conclusions:
- Increased FE of specific amino acids in the elderly is attributed to decreased tubular reabsorption, not altered serum levels or GFR.
- Changes in tubular sodium transport likely influence tubular amino acid transport in older individuals.
- These findings highlight potential mechanisms for altered amino acid homeostasis in aging kidneys.