[The major physiologic stages of advancing age]

Alterations of the function of two essential organs during ageing is studied: the heart and the kidney. Anatomical and hemodynamic alterations secondary to cardiac ageing are considered along with the essential role of coronary atherosclerosis. Clinical consequences because of the decreased performance of the left ventricle ensue, especially a diminution of the adaptability during stress. As far as ageing of the kidney is concerned, physiological consequences are studied, especially the renal clearance which conditions the therapeutic and/or toxic effect of medications. The difficulties of a reliable reflection of the condition of the kidneys by blood creatinin measurements, are demonstrated, because of the diminution of the lean mass and dehydration in elderly patients. Because of the difficulties in collecting 24 hours urine, methods of measurement of the creatinin clearance by estimation from blood creatinin levels are proposed.