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World J Nephrol. Oct 6, 2012; 1(5): 123-126
Published online Oct 6, 2012. doi: 10.5527/wjn.v1.i5.123
Creatinine, urea, uric acid, water and electrolytes renal handling in the healthy oldest old
Carlos Guido Musso, Joaquín Álvarez Gregori, José Ricardo Jauregui, Juan Florencio Macías Núñez
Carlos Guido Musso, José Ricardo Jauregui, Ageing Biology Unit, Hospital Italiano of Buenos Aires, Gascón 450, Argentina
Joaquín Álvarez Gregori, Juan Florencio Macías Núñez, Geriatrics, University of Salamanca, Calle de los Libreros 25, 37008 Salamanca, Spain
Author contributions: All authors contributed to this manuscript.
Correspondence to: Carlos Guido Musso, MD, PhD, Ageing Biology Unit, Hospital Italiano of Buenos Aires, Gascón 450 Argentina. carlos.musso@hospitalitaliano.org.ar
Telephone: +54-11-42442148
Received: July 13, 2011
Revised: June 9, 2012
Accepted: September 25, 2012
Published online: October 6, 2012

Renal physiology in the healthy oldest old has the following characteristics, in comparison with the renal physiology in the young: a reduced creatinine clearance, tubular pattern of creatinine back-filtration, preserved proximal tubule sodium reabsorption and uric acid secretion, reduced sodium reabsorption in the thick ascending loop of Henle, reduced free water clearance, increased urea excretion, presence of medulla hypotonicity, reduced urinary dilution and concentration capabilities, and finally a reduced collecting tubules response to furosemide which expresses a reduced potassium excretion in this segment due to a sort of aldosterone resistance. All physiological changes of the aged kidney are the same in both genders.

Keywords: Ageing, Renal, Creatinine, Urea, Uric acid, Water, Electrolytes, Oldest old