It is important to note that a significant proportion of people are asymptomatic, and the diagnosis relies on pathologic evidence of kidney damage such as hematuria and/or proteinuria, or laboratory evidence of a reduction in the glomerular filtration rate (GFR) with an elevated serum creatinine.
Signs and symptoms are often vague, including fatigue (which may be related to uremia or the anemia associated with CKD), nausea, and possibly the development of edema. Uremic illness is due largely to the accumulation of organic waste products that are normally cleared by the kidneys, and symptoms may be present to some degree in the early stages of kidney failure. As kidney failure progresses to the more advanced stages of uremia, patients will often describe anorexia, nausea, vomiting, restless legs, pruritus, and overall not feeling well. If patients begin to have a lack of urine production, then the resulting fluid overload may be present with dyspnea and orthopnea due to pulmonary edema. Cognition may be affected in all stages of CKD. In the most advanced stages of uremia, patients may present with seizures or coma.
Signs as a consequence of CKD are hypertension, peripheral edema (due to sodium retention and exacerbated by hypoalbuminuria), and pallor due to anemia. Physical exam findings are also directed toward the discovery of end-organ damage associated with causative disease states such as diabetes or hypertension, which cause CKD. A fundoscopic eye exam is critical for the diagnosis of diabetic or hypertensive retinopathy as evidence of microvascular damage that has likely occurred in the kidney, resulting in CKD. In men, a rectal exam for prostatic enlargement or for the diagnosis of prostate nodules can be helpful in determining a diagnosis of obstructive uropathy. In glomerular nephrotic and nephritic syndromes, the signs and symptoms of CKD may present more acutely with accelerated hypertension, periorbital and peripheral edema, rashes, or arthritis on musculoskeletal exam for patients with autoimmune disorders. Patients may describe their urine as foamy if significant proteinuria is present, or tea- or cola-colored in the setting of hematuria.
Most people are unaware that they have CKD and are informed only after abnormalities are discovered by blood and/or urine tests. The first diagnostic tests to order are a serum creatinine (as part of renal chemistry), estimated GFR (with consideration of serum cystatin-C in people with extremes of muscle mass), and urinalysis to assess for hematuria and proteinuria. For the diagnosis of CKD, urinary albumin assessment is usually preferred to that of total urine protein with calculation of the albumin excretion rate or the albumin to creatinine ratio. However, nephrotic level proteinuria is conventionally defined as >3.5 g proteinuria per 24 hours.
Renal ultrasound is required to evaluate kidney size, mass lesions, urinary tract obstruction, and, with a duplex examination, renal arterial flow.
Kidney biopsies are performed in the minority of patients with CKD. A kidney biopsy to determine a pathologic diagnosis is indicated if a glomerular nephrotic or nephritic syndrome is suspected, or in people with diabetes with atypical presentations such as rapidly progressive kidney failure. Nephrotic syndrome may be suggested by proteinuria, and both nephritic and nephrotic syndromes may be suggested by severe presenting symptoms (accelerated hypertension, periorbital and peripheral edema) or with symptoms of underlying autoimmune diseases (rashes or arthritis). Certain infections, such as hepatitis B and C, syphilis, and streptococcal pharyngitis are associated with glomerular disorders. A kidney biopsy is essential in these cases to determine the pathologic lesion.
Imaging of the genitourinary tract may be helpful in the evaluation of a patient with CKD. A plain abdominal x-ray is a nonspecific test that may aid in the detection of calcium-containing kidney stones. Other radiologic tests, such as an abdominal computed tomography, are reserved for evaluation of stone disease and further characterization of renal cystic or mass lesions. Magnetic resonance imaging is reserved for renal mass lesions such as renal cell carcinoma.
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