LabMed

BUN and/or Creatinine Increased: Intrarenal Cause

Differential Diagnosis

Congenital kidney anomalies

Diseases of the kidney associated with a cystic mass

Diseases of the kidney associated with a solid mass

Diseases without a mass primarily manifested as glomerular defects

Diseases without a mass in which there is primarily tubular or interstitial (tubulointerstitial) disease

Suggested Additional Lab Testing

For diseases associated with no mass that are glomerular or tubular, urinalysis is informative.

  • Glomerular disease is suggested by a high amount of urinary protein (including albumin) and red blood cell (RBC) casts with or without loose RBCs.

  • Tubular disease is suggested by a moderate degree of urinary protein that is primarily not albumin or other relatively high-molecular-weight proteins.

  • Granular or white blood cell (WBC) casts or loose WBCs in the urine are often associated with infection.

Because tubular dysfunction can be caused by infections and exposure to drugs, tests for infectious diseases and drug levels can be important.

Renal stones of different composition and multiple myeloma may produce tubular disease.

  • Tests for renal stones and multiple myeloma involve urinalysis and blood testing.

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