Chronic Kidney Disease in Primary Care

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

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

Prevention

Knowledge of the risk factors for the development of chronic kidney disease is crucial to prevention of the disease process. Diabetes mellitus and hypertension are the leading causes of chronic kidney disease; therefore, these risk factors must be tightly controlled in all patients. Glycemic and hypertensive control is discussed in more detail later in this review. In addition, medication lists should be reviewed closely with patients to ensure that any potentially nephrotoxic medications are being used appropriately and in correct dosages. In particular, over-the-counter medications should be evaluated for the potential of drug interactions and nephrotoxicity. Nonsteroidal anti-inflammatory drugs (NSAIDs) are notoriously nephrotoxic and physicians may underestimate their patient's usage of these medications unless they specifically inquire.

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Table 1. Classifications of Chronic Kidney Disease
Stage	Associated GFR (mL/minute/1.73m²)
1	>90 with persistent kidney damage^*
2	60–89 with persistent kidney damage^*
3	30–59
4	15–29
5	<15

*Kidney damage includes both functional damage (proteinuria, glomerulonephritis) and structural damage (polycystic kidneys).
GFR, glomerular filtration rate.

Table 2. Potential Causes of Chronic Kidney Disease
Diagnosis	Clinical Indicators
Diabetes mellitus	Classical clinical course of microalbuminuria, followed by clinical proteinuria, hypertension, and then declining GFR.
Hypertension	Usually characterized by severely elevated blood pressure readings over a long period, with associated end-organ damage in addition to kidney disease.
Nephrotoxic medications	Review prescribed and over-the-counter medications as well as intravenous contrast dye or gadolinium exposure.
Systemic lupus erythematosus	Evaluate for photosensitivity, malar/discoid rashes, oral ulcers, arthritis, serositis, neurological symptoms, hematological findings, ANA/dsDNA positive.
HIV nephropathy	Signs and symptoms of immunodeficiency; HIV positive on testing.
Congestive heart failure	Signs and symptoms of heart failure present. Because fluid overload is common in chronic kidney disease, diagnosis is made through echocardiogram to evaluate systolic and diastolic heart function.
Genetic syndromes	Evaluation of family history is suggestive.
Hepatorenal syndrome	History or evidence of cirrhosis with resultant portal hypertension, ascites, and renal vasoconstriction. Classically lack significant proteinuria.
Nephrolithiasis	Evaluate for history of hematuria and symptoms of renal colic. Long-standing obstruction can cause permanent renal impairment.
Benign prostatic hypertrophy	Evaluate male patients for hesitancy, straining, or weak flow during urination and nocturia. Confirm with prostate exam.
Glomerulonephritis	Broad category of diseases including postinfectious (streptococcal) as well as various vasculitis diseases. Urinalysis suggestive with presence of red blood cell casts.

GFR, glomerular filtration rate; ANA, antinuclear antibodies; dsDNA, double-stranded deoxyribonucleic acid; HIV, human immunodeficiency virus.

Table 3. Dosage of Diabetic Medications in Chronic Kidney Disease
Diabetic Medication	Renal Dosage*
Biguanines
Glucophage (metformin)	Renal impairment: avoid use
Sulfonureas
Glucotrol (glipizide)	CrCl^† <50: decrease dose by 50%
Diabeta (glyburide)	CrCl^† <50: avoid use
Amaryl (glimepiride)	Renal impairment: start 1 mg daily, increase slowly, monitor glucose
Glitazones
Actos (pioglitazone)	No adjustment
Avandia (rosiglitazone)	No adjustment
Alpha-glucosidase inhibitors
Precose (acarbose)	Creatinine >2: avoid use
Glyset (miglitol)	Creatinine >2: avoid use
Meglitinides
Starlix (nateglinide)	No adjustment
Prandin (repaglinide)	CrCl 20–40: start 0.5 mg before every meal, use titrate with cautionCrCl <20: not defined
Incretin mimetics
Byetta (exenatide)	CrCl 30–80: no adjustmentCrCl <30 & HD: not recommended
Januvia (sitagliptin)	CrCl 30–49: 50 mg dailyCrCl <30: 25 mg dailyHD/CAPD: no supplement

*Dosing recommendations according to Epocrates Essentials (Epocrates Inc., San Mateo, CA).
^† Calculated by Cockroft-Gault equation.
CrCl, creatinine clearance (mL/min); HD, hemodialysis; CAPD, continuous ambulatory peritoneal dialysis.