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Test Code RPCWT Renal Pathology Consultation, Wet Tissue

Shipping Instructions

1. Advise shipping specimens in Styrofoam transportation coolers to avoid extreme hot or cold temperatures to ensure specimens are received at required specimen stability temperature.

2. Attach the green pathology address label included in the kit to the outside of the transport container.

Specimen Required

Supplies: Renal Biopsy Kit (T231)

Source: Kidney

Container/Tube: Renal Biopsy Kit (T231)

Specimen Volume: Entire specimen

Collection Instructions: Collect specimens according to the instructions in Renal Biopsy-Procedures of Handling Tissue for Light Microscopy, Immunohistology, and Electron Microscopy in Special Instructions.


1. Renal Biopsy Patient Information in Special Instructions

2. Renal-Biopsy Procedures of Handling Tissue for Light Microscopy, Immunohistology, and Electron Microscopy in Special Instructions

3. If not ordering electronically, complete, print, and send a Pathology Test Request Form (T246) with the specimen (

Secondary ID


Useful For

The evaluation and management of patients with kidney disease


Following the progression of known renal disease or response to therapy


Determining the cause of dysfunction in the transplanted kidney (allograft)

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
LV4RP Level 4 Gross and Microscopic, RB No No
EMR EM, Renal Biopsy No No
SS2PC SpecStain, Grp II, other No No
IFPCI IF Initial No No
IFPCA IF Additional No No

Testing Algorithm

The Renal Pathology Consultation is performed by a Mayo Clinic renal pathologist and entails the performance of appropriate procedures and stains based on the material received, patient information and specific findings on the case in order to determine a diagnosis. Optimal/standard diagnostic interpretation of a medical kidney biopsy requires integration of the light microscopy, immunofluorescence, and electron microscopy findings together with the clinical and laboratory data for the patient. We follow published standards by the Renal Pathology Society for the diagnostic evaluation and reporting of non-neoplastic renal disease.(1)


Light Microscopy:

Wet/unprocessed tissue submitted for light microscopy routinely includes the preparation of stains, which include hematoxylin and eosin (H and E), periodic acid Schiff (PAS), Masson trichrome, and Jones methenamine silver stains.



Wet/unprocessed tissue submitted for immunofluorescence may include the following stains in order to render an accurate diagnosis. These stains include: IgA, IgG, IgM, C1q, C3, albumin, fibrinogen, kappa light chain, and lambda light chain stains with C4d added if the biopsy is an allograft.


The IgG subtypes (IgG1, IgG2, IgG3, IgG4) are typically only utilized if the biopsy shows features suspicious for a monoclonal/monotypic deposition process involving IgG.


Alport (collagen IV, alpha 2 and alpha 5) staining is performed in the setting of biopsy findings that are consistent with hereditary nephritis/Alport syndrome.


Phospholipase A2 Receptor (PLA2R) staining is performed in the setting of membranous nephropathy/glomerulonephritis to aid in determining whether it is most likely primary/idiopathic or secondary. 


Paraffin-Based Immunofluorescence Stains:

The paraffin-based immunofluorescence stains listed above would only be utilized in the special circumstance when there is no tissue or inadequate tissue available for standard immunofluorescence or if there are findings that raise concern for so-called "masked deposits”.


Electron Microscopy:

Wet/unprocessed tissue submitted for electron microscopy will be processed for transmission electron microscopy. A formal interpretive report is issued, incorporating the findings from all tests performed for diagnostic purposes.


See Pathology Consultation Ordering Algorithm in Special Instructions.

Method Name

Pathology Consultation

Reporting Name

Renal Pathology

Specimen Type

Kidney Biopsy

Specimen Minimum Volume

Entire Specimen

Specimen Stability Information

Specimen Type Temperature Time
Kidney Biopsy Ambient (preferred)

Reject Due To









Clinical Information

The Mayo Renal Pathology service is staffed by board-certified pathologists who have a special interest in non-neoplastic diseases of the kidney.


Kidney biopsy has proven to be of value in the clinical evaluation and management of patients with kidney disease, including acute and chronic renal insufficiency, nephrotic syndrome, nephritic syndrome, proteinuria and hematuria, and in the overall management of renal transplant recipients.


Optimal interpretation of a kidney biopsy requires integration of clinical and laboratory results with light microscopic, immunofluorescent histology, and electron microscopy findings.

Reference Values

An interpretive report will be provided.


A verbal report of the findings is typically communicated by phone to the submitting nephrologist, and an initial report based on the light microscopic and immunofluorescent histology interpretation is also faxed to the nephrologist. A report is also sent to the submitting pathology laboratory.


Representative electron microscopy images and significant positive immunofluorescent stain findings can be provided on a CD upon request.


In most cases, the electron microscopy results are reported as an addendum and a final report is issued including these findings. This final report is again faxed to the submitting nephrologist and mailed to the submitting pathology laboratory, along with a representative set of the light microscopy slides.

Clinical Reference

Chang A, Gibson IW, Cohen AH, et al: A position paper on standardizing the nonneoplastic kidney biopsy report. Clin J Am Soc Nephrol 2012;7:1365-1368

Day(s) and Time(s) Performed

Monday through Friday

Rush (same day as receipt) interpretation is also available on Saturday and holidays for clinically emergent cases (eg, acute renal failure, rapidly progressive glomerulonephritis, acute kidney allograft dysfunction) but requires advanced notification and approval by a Mayo renal pathologist.

Analytic Time

Routine cases: 1 working day/2 to 10 days for electron microscopy. Rush (same day as receipt) interpretation requires advance notification and approval by a Mayo renal pathologist.

Performing Laboratory

Mayo Medical Laboratories in Rochester

CPT Code Information






LOINC Code Information

Test ID Test Order Name Order LOINC Value
RPCWT Renal Pathology In Process


Result ID Test Result Name Result LOINC Value
71219 Interpretation In Process
71220 Participated in the Interpretation No LOINC Needed
71221 Report electronically signed by 19139-5
71222 Addendum In Process
71223 Gross Description 22634-0
71224 Material Received 81178-6
71615 Disclaimer 62364-5
71846 Case Number In Process