The nurse is caring for an elderly patient who was admitted with renal insufficiency.The nurse realizes that with advance age often comes declining renal function.An expected laboratory finding for this patient may be:

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The most important renal physiological change that occurs with aging is a decrease in the GFR.After age 40,renal blood flow gradually diminishes at a rate of 10% per decade.With advancing age,there is also a decrease in renal mass,the number of glomeruli and peritubular density.Serum creatinine levels may remain the same in the elderly patient,even with a declining GFR,because of decreased muscle mass and hence decreased creatinine production.Tubular changes include a diminished ability to excrete drugs,including radiocontrast dyes used in diagnostic testing,which necessitates a decrease in drug dosing to avoid nephrotoxicity.Many medications,including antibiotics,require dose adjustments as kidney function declines.Age-related changes in renin and aldosterone levels also occur,which can lead to fluid and electrolyte abnormalities.Renin levels are decreased by 30% to 50% in the elderly,resulting in less angiotensin II production and lower aldosterone levels.Together these can cause an increased risk of hyperkalemia.The aging kidney is also slower to correct an increase in acids,causing a prolonged metabolic acidosis and the subsequent shifting of potassium out of cells and worsening hyperkalemia.

The Nurse Is Caring for an Elderly Patient Who Was