Early indicators of deteriorating renal efficiency in elderly subjects

Renal functions decline with age. Only after considerable renal reserves are lost, the traditional clinical tests of urine, blood or clearance levels reveal the defect. The urine quantity & contents passed in 24 hrs both by young and elderly, show little differences between the two groups. Their creatinine clearances are also comparable. Earlier Studies on water dilution test had shown significant differences between the performance of the young and elderly subjects, indicating decrease in renal efficiency on ageing. In the present study 4 hourly collections of urine showed that the night collections in elderly subjects were comparatively larger in volume, electrolytes and other components as compared with younger subjects. The kidneys of the elderly seem to compensate by labouring at night, while the young have their restful phase. Thus in addition to water dilution test, comparison of day/night outputs of urine can be taken as an early indicator of renal deterioration in elderly.