Chronic kidney disease

Chronic kidney disease (CKD), also known as chronic renal failure, is a progressive loss in glomerular function caused by a long standing renal parenchymal disease. It is present when the glomerular filtration rate (GFR) is less than 60 ml/min/1.73 m² for three consecutive months or greater than or equal to this value in patients with a kidney damage that is present for three or more months ¹.

Epidemiology

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Clinical presentation

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Pathology

A variety of different diseases can affect and cause damage to the renal parenchyma, the most common are ²:

• diabetes (diabetic nephropathy) 
• hypertension
• glomerulonephritis 
• polycystic kidney disease

Classification

CKD is divided in five stages based on the GFR (ml/min/1.73 m²) ¹:

• >90: Stage 1: kidney damage with normal or elevated GFR
• 60-89: Stage 2: kidney damage with mild reduction in GFR
• 30-59: Stage 3: moderate reduction in GFR
• 15-29:- Stage 4: severe reduction in GFR
• <15 (or dialysis): Stage 5: kidney failure (this stage is also known as end-stage kidney disease (ESKD))

The same conference ¹ suggests that CKD could also be classified by treatment type:

• kidney transplant recipient 
• CKD independent of dialysis
• CKD on dialysis

Radiographic features

There is no specific imaging features for CKD, the diagnosis is based on clinical and laboratorial findings. Radiological exams, especially ultrasound, are performed in most of cases for aetiological investigation (e.g. renal artery stenosis, polycystic kidney disease, hydronephrosis, etc) and for treatment follow-up.

US

Ultrasound with Doppler examination of intrarenal vessels is usually performed in patients with CKD and it is common to have a normal exam.

Typical B-mode findings of a long standing severe CKD (especially stage 5) are ²:

• reduced renal length
• reduced renal cortical thickness
• increased renal cortical echogenicity 
• poor visibility of the renal pyramids and the renal sinus
• marginal irregularities
• papillary calcifications
• cysts (see also: acquired cystic kidney disease)

Abnormal Doppler findings in these patients are ²:

• reduced renal vascularity
• increased RI values (segmental and interlobular arteries)

MRI

IV gadolinium contrast has been associated with nephrogenic systemic fibrosis (NSF) in the setting of chronic kidney disease. The threshold that is a contraindication for administration of gadolinium contrast is institution dependent and also depends on the dose and type of contrast agent being used, but a GFR of 20-30 is generally considered a contraindication, and a GFR of 30-60 usually necessitates a smaller dose. Dialysis is a contraindication.

Treatment and prognosis 

Stage 3 CKD patients are reported to be 20 times more likely to die of a cardiovascular event than to reach end-stage renal disease ³. Chronic vascular disease is a common CKD associated complication and deserves a special attention ¹. A large study evidenced that treatment and prevention of coronary artery disease, congestive heart failure, diabetes mellitus, and anemia should be the target treatment to reduce the mortality of patients with CKD ³.