Doctor Patel in the lab

Your Kidney Biopsy

You had a biopsy done of one of your kidneys, now what?

The 1-2 cm tissue core that was obtained is handled very carefully and portions are placed in special fixatives for transport to the laboratory. Because the interpretation of a kidney biopsy is very complex, the biopsy is sent to a laboratory such as ProPath, which is staffed by expert pathologists with specialized training and expertise in kidney biopsy interpretation. These pathologists are physicians, and are often referred to as Renal Pathologists or Nephropathologists.  

When the biopsy reaches ProPath it is accessioned into a secure laboratory computer system and processing is begun in the laboratory. A portion of the biopsy is processed for “light microscopy”, a portion for “immunofluorescence” and a portion for “electron microscopy”.

The light microscopic slides are permanent slides and each contains several very thin, specially stained, sequential slices of the kidney biopsy. The pathologist examines the glomeruli, the filtering units of the kidney; the tubules which carry the filtered liquid that eventually becomes urine through the kidney, and the blood vessels which supply blood and nutrients to the kidney. Each of these structures, if damaged, can lead to abnormal function of the kidneys, and this damage can be identified as these slides are examined.

In some kidney diseases there is deposition of abnormal material in the glomeruli,which causes damage that results in the spilling of protein or blood into the urine.Examination of tissue by immunofluorescence is important to identify these subs-tances. Tissue examined by immunofluorescence is frozen very quickly and the sections are cut using a cryostat. The sections are stained with special stains that allow detection of these abnormal substances. The stains have fluorescent properties and any positive staining is easily detected using a special microscope.

The third component necessary for the complete examination of your kidney biopsy is electron microscopy. The tiny pieces of kidney tissue are placed in aspecial fixative and processed much like the tissue processed for light microscopy, except that the tissue fragments are embedded in plastic. The tiny slices of plastic embedded tissue are placed on small copper grids, stained and examined using an electron microscope. The electron microscope allows magnification of the biopsy to several thousand times so that the fine structure of the glomerulus can be examined, and abnormalities detected.

A final comprehensive report incorporating the results of all of these tests is prepared. The final diagnosis is discussed with your doctor and correlated with your medical history, physical examination and laboratory results. A final report is issued usually within 1-3 days of receipt of your biopsy, and is relayed to your physician. It is possible for you and your doctor toview the biopsy remotely via a secure link to ProPath’s network while discussing the findings with the Renal Pathologist.


National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC)