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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.

Necessary Information

Note: Requisitions for this procedure cannot be processed unless the listed necessary information  is supplied.

1. All requisitions must be labeled with:

-Patient name

-Date of birth

-Medical record number

-Ordering physician

-Anatomic site

-Collection date

2. All specimens must be labeled with:

-Two patient identifiers (first and last name, date of birth or medical record number).

-Anatomic site

Specimen Required

Specimen Type: Tissue

Supplies: Renal Biopsy Kit (T231)

Source: Kidney

Specimen Volume: Entire specimen

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


1. Renal Biopsy Patient Information in Special Instructions

2. Renal Biopsy Procedures for Handling Tissue for Light Microscopy, Immunohistology, and Electron Microscopy

3. If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.

Useful For

Evaluating and managing 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. Published standards by the Renal Pathology Society are followed 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

Method Name

Pathology Consultation

Reporting Name

Renal Pathology

Specimen Type

Kidney Biopsy

Specimen Minimum Volume

See Specimen Required

Specimen Stability Information

Specimen Type Temperature Time Special Container
Kidney Biopsy Ambient (preferred)

Reference Values

An interpretive report will be provided.

Day(s) Performed

Monday through Friday

Rush (same day as receipt) interpretation is 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.

Report Available

2 to 10 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

88305 (If appropriate)

88348 (If appropriate)

88313 (If appropriate)

88346 (If appropriate)

88350 (If appropriate)


LOINC Code Information

Test ID Test Order Name Order LOINC Value
RPCWT Renal Pathology 65757-7


Result ID Test Result Name Result LOINC Value
71219 Interpretation 60570-9
71220 Participated in the Interpretation No LOINC Needed
71221 Report electronically signed by 19139-5
71222 Addendum 35265-8
71223 Gross Description 22634-0
71224 Material Received 85298-8
71615 Disclaimer 62364-5
71846 Case Number 80398-1

Test Classification

Not Applicable