Diagnosis
History and physical examination are central to the diagnostic workup in nephrology. This may include inquires regarding family history, general medical history, diet, medication use, drug use and occupation. Examination typically includes an assessment of volume state, blood pressure, skin, joints, abdomen and flank.
Examination of the urine (urinalysis) allows a direct assessment for possible kidney problems, which may be suggested by appearance of blood in the urine (haematuria), protein in the urine (proteinuria), pus cells in the urine (pyuria) or cancer cells in the urine. A 24 hour urine collection can be used to quantify daily protein loss (see Proteinuria), urine output, creatinine clearance or electrolyte handling by the renal tubules.
Basic blood tests can be used to check the concentration of haemoglobin, platelets, sodium, potassium, chloride, bicarbonate, urea, creatinine, calcium, magnesium or phosphate in the blood. All of these may be affected by kidney problems. The serum creatinine concentration can be used to estimate the function of the kidney, called the creatinine clearance or estimated glomerular filtration rate. More specialized tests can be ordered to discover or link certain systemic diseases to kidney failure such as infections (hepatitis B, hepatitis C), autoimmune conditions (systemic lupus erythematosis, ANCA vasculitis), paraproteinemias (amyloidosis, multiple myeloma) and metabolic diseases (diabetes, cystinosis).
Structural abnormalities of the kidneys are identified with imaging tests. These may include ultrasound, computed axial tomography (CT), scintigraphy (nuclear medicine), angiography or magnetic resonance imaging (MRI).
In certain circumstances, less invasive testing may not provide a certain diagnosis. Where definitive diagnosis is required, a biopsy of the kidney (renal biopsy) may be performed. This typically involves the insertion, under local anaesthetic and ultrasound guidance, of a core biopsy needle into the kidney to obtain a small slither of kidney tissue. The kidney tissue is then examined under a microscope, allowing direct visualization of the changes occurring within the kidney. Additionally, the pathology may also stage a problem affecting the kidney, allowing some degree of prognostication. In some circumstances, kidney biopsy will also be used to monitor response to treatment and identify early relapse.
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