A. A nephrologist performs a number of tests and treatments to identify various kidney illnesses and disorders. In-lab examinations: The patient's blood or urine sample is typically used for laboratory tests. Again, a nephrologist can examine the results of many different tests to determine how well the kidneys are working. Blood tests: - GFR or Glomerular filtration rate - Serum creatinine - BUN or Blood urea nitrogen Urine tests: - Urinalysis - ACR or Albumin/creatinine ratio - Creatinine clearance