Proteinuria

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Tests

The reasons for looking for protein in the urine include screening those at risk, looking for a cause for proteinuria, evaluating the type and quantity of protein being released, and assessing kidney function. When proteinuria is detected, patients are monitored at intervals to see if it gets better or becomes worse. Both urine and blood tests may be requested to evaluate proteinuria.

Laboratory Tests

Several tests may be requested on either  24-hour or random urine samples:

  • Urinalysis– evaluation of a urine sample by visual inspection, chemical testing with a simple dip stick and, in some cases, microscopic examination.
  • Microalbumin, 24-hour urine – a more sensitive test for proteinuria that is used to detect and monitor kidney function in diabetic patients.
  • Urine protein, 24-hour urine – measures the amount of protein passed in the urine over a 24-hour period; this is a more accurate assessment of the degree of proteinuria than a random urine measurement.
  • Microalbumin/creatinine ratio (ACR), random urine - measures albumin in a random sample and corrects for the volume of urine passed by measuring the amount of creatinine in urine (a substance released by the body at a steady rate); this is more convenient than having to collect a 24-hour sample.
  • Urine protein/creatinine ratio (UPCR), random urine - measures protein in a random sample and corrects for the volume of urine passed by measuring the amount of creatinine in urine; this is more convenient than having to collect a 24-hour sample.
  • The following tests may also be requested and are measured primarily on blood alone:

  • eGFR (estimated Glomerular Filtration Rate) - uses a blood creatinine level to calculate the estimated rate of urine filtration; rate decreases with progressive kidney damage.
  • Creatinine - a blood test used to evaluate kidney function; less frequently, it may be done on urine. (Note: Although creatinine may be measured in urine samples, it is usually measured to be included as part of a ratio or calculation.)
  • Total Protein - a blood test that measures all of the protein in the serum.
  • Albumin - a blood test that measures the concentration of albumin in blood.
  • A kidney biopsy may also be requested. This is a procedure that is sometimes done to look at a small sample of kidney tissue under the microscope to look for evidence of kidney disease or damage.

    Non-Laboratory Tests

  • Imaging scans of the kidney to detect the presence and determine the severity of kidney disease or damage.
  • Blood pressure; may be measured as part of investigation of cause of proteinuria; frequently monitored in those who have hypertension or are at risk of developing it.
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