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Module 23

Module Leader:

Todd Pesavento, M.D.

Geriatric Objectives:

  1. List five causes of ARF in the elderly
  2. Name the drug of choice in the treatment of hypertension in the elderly.
  3. Name the most common cause of biopsy proven intrinsic renal disease in the elderly.
  4. List why elderly patients have a widened pulse pressure
Learning Resources:

Those listed in the front of your module packet.

Short Summary:

Renal disease is common in the geriatric population but frequently is misdiagnosed and commonly underdiagnosed. This in part relates to the normal aging process in which elderly patients experience an age-related decline in the glomerular filtration rate. At the same time, there is a disproportionately larger decline in their muscle mass. As a result, elderly patients should have a serum creatinine that is lower than what is considered “normal”. Failure to recognize a subtle elevation or “normal” creatinine as being abnormal can lead to incorrect dosing of medications and the delay in diagnosis of renal failure.

In general the same principles used the evaluation of renal dysfunction of any patient should apply to the geriatric patient. There are subtle differences in the elderly that one should be aware.

Acute Renal Failure (ARF)

ARF more common in the elderly than in younger adults. Potential reasons for this include:

  1. Changes in anatomy and physiologic situations as the patients (and kidneys age)
  2. The presence of comorbid conditions including vascular disease and diabetes
  3. Frequent use of non-steroidal anti-inflammatory drugs
  4. Volume depletion due to diuretics
  5. Higher prevalence of obstructive uropathy

    Non-steroidal anti-inflammatory drug-induced ARF occurs more commonly in the elderly due to coexistence of conditions associated with volume depletion superimposed on chronic renal insufficiency.

    The most common cause of biopsy proven intrinsic renal disease in the elderly is a rapidly progressive glomerulonephritis (RPGN) and of these, vasculitus and idiopathic cresentic glomerulonephritis make up more than half of the cases. These disease can be curable is treated aggressively and if found in a timely manner. Thus, the importance of an elevated creatinine in the elderly should not be diminished and a thorough work-up should be pursued.
Hypertension

Hypertension is a common disease in the elderly, affecting 25% of whites and 33% of black patients greater than 65 years of age. The pathophysiology of hypertension in the elderly is similar to that of younger patients with a few exceptions. Importantly, rennin levels in the elderly are generally low and their hypertension is more responsive to sodium restriction and volume depletion.

Elderly patients typically have a decrease in the elasticity of their connective tissue and an increase in the prevalence of atherosclerosis. These changes lead e to a disparate systolic pressure and a widened pulse pressure.

Hypertension presenting after age 55 should trigger an evaluation of secondary causes and given the high prevalence of vascular disease in the elderly, renovascular hypertension should be excluded.

Once the diagnosis of hypertension is made, a multi-faceted approach of therapy should be attempted. Specifically, dietary sodium restriction and weight loss may increase the likelihood that a patient may be able to be tapered off anti-hypertensive therapy in the future. Other lifestyle modifications appropriate for all patients should be used, including review of their medication lists, especially over the counter medications.

If lifestyle modification is not successful, the first line therapy should be a diuretic. Hydrochlorothiazide is often effective at half of the normal starting dose. Other therapies could be used in patients with other co morbid conditions, such as the use of a beta blocker in a patient with coronary artery disease or an angiotensin converting enzyme inhibitor in a patient with diabetes. The goal level of blood pressure control should be a systolic pressure less than 140 and a diastolic under 90. The Recent Joint Council Committee-six (JNC-VI) outlines the current recommendation for treatment of hypertension in the elderly.

A subtle but important difference in the treatment of hypertension in the elderly is an exaggerated effect that treatment has on blood pressure in these patients. Postural hypotension may occur and cause significant dizziness. Over treatment of blood pressure may lead to end organ underperfusion of the heart, brain, kidney and mesentery. Assessment for these symptoms should be part of each clinic visit.