It is important to note that a significant proportion of people are asymptomatic, and the diagnosis relies on pathological evidence of kidney damage such as haematuria 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 uraemia or the anaemia associated with CKD), nausea, and possibly the development of oedema. Uraemic 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 uraemia, 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 dyspnoea and orthopnoea due to pulmonary oedema. Cognition may be affected in all stages of CKD. In the most advanced stages of uraemia, patients may present with seizures or coma.
Signs as a consequence of CKD are hypertension, peripheral oedema (due to sodium retention and exacerbated by hypoalbuminaemia), and pallor due to anaemia. Physical examination findings are also directed towards the discovery of end-organ damage associated with causative disease states such as diabetes or hypertension, which cause CKD. A fundoscopic eye examination is critical for the diagnosis of diabetic or hypertensive retinopathy as evidence of microvascular damage that has probably occurred in the kidney, resulting in CKD. In men, a rectal examination 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, peri-orbital and peripheral oedema, rashes, or arthritis on musculoskeletal examination for patients with autoimmune disorders. Patients may describe their urine as foamy if significant proteinuria is present, or tea- or cola-coloured in the setting of haematuria.
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 haematuria 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 (AER) or the albumin to creatinine ratio (ACR). 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 a minority of patients with CKD. A kidney biopsy to determine a pathological 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 oedema) 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 pathological lesion.
Imaging of the genitourinary tract may be helpful in the evaluation of a patient with CKD. Plain abdominal x-ray is a non-specific test that may aid in the detection of calcium-containing kidney stones. Other radiological tests, such as an abdominal computed tomography, are reserved for evaluation of stone disease and further characterisation of renal cystic or mass lesions. Magnetic resonance imaging is reserved for renal mass lesions such as renal cell carcinoma.
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