Our findings indicate that there seems to be a net reabsorption of creatinine in the renal tubules of healthy old persons.

Renal reserve is preserved in healthy very old people, but its magnitude decreases significantly with age.

Furosemide test showed a significantly lower average post-furosemide FE of potassium value, delayed post-furosemide peak FE of Na, K and Cl and a hormonal pattern of aldosterone resistance in very old people.

No abstract

Serum levels and FE of calcium, phosphorus, magnesium and uric acid were significantly higher in CKD patients compared to healthy very old people with similar GFR, except for serum magnesium and FE of uric acid, which were similar in both groups.