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

Etiology

Chronic kidney disease can be a manifestation of another chronic illnesses that are causing end-organ renal damage, such as diabetes mellitus or hypertension. Alternatively, chronic kidney disease can be an intrinsically renal disease, such as polycystic kidney disease. Therefore, at diagnosis of chronic kidney disease, family physicians must determine the underlying etiology so that the treatment plan can be appropriately directed.

Diabetes is the most prominent cause of chronic kidney disease, accounting for 33% of adult chronic kidney disease cases.[3] Conversely, 20% to 40% of diabetics will develop diabetic nephropathy during the course of their disease;[8] therefore, as the number of diabetic patients increases, the incidence of chronic kidney disease can be expected to follow. Diabetic nephropathy follows a classical progression that, when present, often negates the need for a renal biopsy to confirm its presence. The initial presentation of diabetic kidney disease is microalbuminuria followed by increasing severity of proteinuria as the glomerular filtration membrane is further damaged. The development of hypertension subsequently occurs, followed by a decline of the GFR.[3] Both type 1 and type 2 diabetes can cause kidney disease; however, because type 2 diabetes is increasingly prevalent, it is more commonly associated with kidney damage than type 1. The onset of diabetic kidney disease closely correlates with the onset of diabetic retinopathy because both are manifestations of microvascular disease;[9] therefore, if retinopathy is not present in a diabetic patient with chronic kidney disease, the nephropathy may not be caused by the diabetes, and other etiologies should be thoroughly evaluated.[8]

Vascular disease (primarily hypertension) is the second most common cause of chronic kidney disease (it causes 21% of adult chronic kidney disease cases).[3] Hypertensive nephrosclerosis is associated with addition signs of hypertensive end-organ damage because of long periods of poorly controlled hypertension. Atherosclerotic renovascular disease is suggested by a sudden worsening of hypertension, with findings of atherosclerosis in non-renal areas. Renal ultrasound may show asymmetrical kidney sizes, with the smaller kidney receiving less blood supply because of its renovascular disease. There are multiple imaging studies that can be used to confirm suspected renal artery stenosis. Duplex Doppler ultrasonography is useful as an initial screening test when renal artery stenosis is suspected in a patient with chronic kidney disease because it does not require administration of intravenous dye. Magnetic resonance angiography with gadolinium must be used judiciously in patients with a GFR <60 mL.min/1.73m2 because of the risk of nephrogenic systemic fibrosis. Similarly, computed tomographic angiography may worsen renal function and should be used cautiously. Renal angiography is the gold standard for confirmation and is useful for therapeutic interventions; however, it also carries the risk of worsening renal function.[10] Among young women with no findings of atherosclerosis, fibromuscular dysplasia should be considered as the etiology of renal artery stenosis.

Differentiation between the various etiologies of kidney damage can be difficult at times and, in all cases, the presence of treatable causes should be assessed. This evaluation begins with a detailed history and physical, with consideration of the broad differential of causes of chronic kidney disease as illustrated in Table 2. If the etiology cannot be elucidated, then consultation with a nephrologist should be considered because a renal biopsy may be indicated.

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