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

Screening: Whom and How?

The patients who are at increased risk of chronic kidney disease are those with long-standing diabetes and/or hypertension; these conditions are the primary contributors to kidney disease. The National Kidney Foundation[3] has identified the following additional risk factors for chronic kidney disease: >60 years old, racial or ethnic minorities, exposure to known nephrotoxins, low income or education level, autoimmune diseases, systemic infections, urinary tract infections, nephrolithiasis, neoplasia, family history of kidney disease, recovery from acute renal failure, reduction in kidney mass, and low birth weight.

The US Preventive Services Task Force currently has no specific screening recommendations for kidney disease.[5] The National Kidney Foundation, however, recommends testing for all patients with diabetes, hypertension, a family history of kidney disease, age >60 years, and ethnic minorities because these are the most prominent risk factors for chronic kidney disease.[3]

For these patients who are at increased risk for chronic kidney disease, it is recommended that the minimal screening for kidney damage include assessment of GFR and proteinuria. Currently, the guidelines for hypertension from the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure guidelines[6] recommend an annual screening urinalysis to assess proteinuria; however, the National Kidney Foundation[3] and the European Society of Cardiology/European Society of Hypertension[7] recommend screening for microalbuminuria. The European Society of Cardiology/European Society of Hypertension state in their 2007 Guidelines for the Management of Arterial Hypertension: "Microalbuminuria has now been considered an essential component in the assessment of organ damage because its detection is easy and relatively inexpensive."[7] A routine urinalysis detects only protein unless an albumin-specific dipstick is used. When the glomerular membrane is damaged, the initial protein that is spilled into the urine is albumin because of its molecular size and negative charge. Therefore, screening for the presence of microalbuminuria is the more sensitive test for detection of early kidney damage. The American Diabetic Association[8] recommends that all diabetic patients have an annual screen for microalbuminuria. Microalbuminuria is considered positive when the level is >30 mg/g; however, there are gender-specific values that have not entered into routine use at this point (>17 mg/g in men and >25 mg/g in women). If the level of proteinuria exceeds 500 mg/g, using an untimed (spot) urine protein/creatinine ratio is recommended to assess the severity of the proteinuria and its response to interventions. Currently, there is agreement among the recommendations for assessment of renal function with screening chemistry and calculated GFR.[3,6–8]

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