Chronic Kidney Disease in Primary Care

Duaine D. Murphree, MD; Sarah M. Thelen, MD

Disclosures

J Am Board Fam Med. 2010;23(4):542-550. 

In This Article

Interventions to Slow the Progression of Kidney Disease

The Modification of Diet in Renal Disease study[11] followed chronic kidney disease patients at all stages for a 2-year period and concluded that 85% of patients had a decline in their GFR, with the average rate of decline 4 mL/min annually regardless of the baseline GFR. There are modifiable and nonmodifiable factors that contribute to this decline. These factors have been shown to be significant regardless of the underlying etiology of the chronic kidney disease. In general, the nonmodifiable risk factors associated with more rapid decline in kidney disease include increased age, African-American race, and male sex. The modifiable risk factors are the focus of treatment to halt disease progression and include higher levels of proteinuria, a lower serum albumin level, higher blood pressure, poor glycemic control, and smoking. Currently there is conflicting data regarding the role of dyslipidemia and anemia in the role of kidney disease progression.[3]

Proteinuria

Because proteinuria contributes to an increase in renal damage, screening and quantification of the presence of proteinuria is critical in the care of chronic kidney disease patients. Random (spot) samples of urine for calculation of the urine protein-creatinine ratio eliminate the need for 24-hour urine collections for quantification of proteinuria. Once proteinuria is identified, its control becomes a high priority. The goal of treatment is to decrease the degree of proteinuria; even low levels of proteinuria are associated with progression of chronic kidney disease and cardiovascular disease.[3]

Angiotensin converting enzyme (ACE) inhibitors are considered first-line medications for proteinuria, regardless of the underlying cause or stage of chronic kidney disease.[3] As such, family physicians should become competent with the initiation of these medications and confidence with monitoring their effects. Because hyperkalemia and slight worsening of renal function can occur with the initiation of ACE inhibitors, these factors should be monitored; however, the medications should not be discontinued without due cause. Mild hyperkalemia (potassium < 5.6 mmol/L) can often be controlled by dietary changes, cessation of NSAID use, and potassium-sparing diuretics, if applicable. In addition, potassium excretion can be enhanced by the addition of a loop diuretic. For hyperkalemia >5.6 mmol/L, the ACE inhibitor should be immediately discontinued and the patient should be treated appropriately. With regard to the concern of acute renal failure related to the initiation of ACE inhibitors, a modest rise in creatinine level (<30% increase) within 1 to 2 weeks of initiation of therapy is considered acceptable. The patient should be monitored to ensure that additional rise does not occur because this would be cause for discontinuation of medication and further evaluation. Renal artery stenosis, hypovolemia, or uncompensated heart failure may be associated with a rise in creatinine level of > 30% and, once treated, the ACE inhibitor may be reinstated safely.[12]

An angiotensin receptor blocker (ARB) may be considered for patients who are unable to tolerate ACE inhibitors. In diabetic kidney disease, an ARB may be used as a first-line alternative to ACE inhibitors.[7] In addition, the candesartan and lisinopril microalbuminuria study demonstrated the benefit of the use of the combination of an ACE inhibitor (lisinopril) with an ARB (candesartan) in patients with diabetic-associated microalbuminuria.[13] The addition of a nondihydropyridine calcium channel blocker, such as diltiazem or verapamil, can further decrease the degree of proteinuria, as can the addition of a thiazide or loop diuretic.[3] However, the blockade of the renin-angiotensin system remains the cornerstone of treatment of proteinuria.

Blood Pressure Control

Strict blood pressure control is a high priority in the care of the patient with chronic kidney disease. For the reasons mentioned above, ACE inhibitors or ARBs are commonly used as the initial medications to achieve blood pressure control; however, often a multidrug regimen is needed. Commonly, diuretics are needed for patients with chronic kidney disease because of the hypertensive effect of volume overload.[14] According to the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure guidelines,[6] the goal blood pressure is <130/80 mm Hg in patients with chronic kidney disease; however, the National Kidney Foundation[3] suggests a more stringent goal of <125/75 mm Hg for patients with chronic kidney disease and significant proteinuria. With the achievement of these blood pressure goals, further kidney damage can be avoided and the progression of the patient's chronic kidney disease can be slowed.

Glycemic Control

Regardless of the cause of chronic kidney disease, tight glycemic control should be achieved for all diabetic patients. The American Diabetic Association recommends a target glycated hemoglobin level of <7.0 for all diabetics, regardless of whether kidney disease is present.[8] Treatment of diabetes in patients with kidney disease can be complicated. Table 3 shows diabetic medications that need dosage adjustments by creatinine clearance. Metformin, which is the cornerstone oral medication for diabetic glycemic control, is contraindicated with creatinine >1.5 in men and 1.4 in women because of the concern about lactic acidosis.

Tobacco Abuse

Cigarette smoking is associated with a more rapid decline in kidney function regardless of the underlying cause of the chronic kidney disease.[3] Smoking cessation should be discussed and encouraged in all smokers with chronic kidney disease, particularly given that cardiovascular disease is the primary cause of mortality among this patient population. Medications used to facilitate smoking cessation, such as Zyban (GlaxoSmithKline, Inc., Research Triangle Park, NC) and Chantix (Pfizer, New York, NY), require dose adjustments in patients with renal disease; however, these can still be useful adjuncts in assistance with successful smoking cessation.

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