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Test ID NBLD0543 Renal Pathology Consultation, Wet Tissue

Reporting Name

RenalPath Consultation, Wet Tissue

Useful For

The evaluation and management of patients with kidney disease


Following the progression of known renal disease and/or response to therapy


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

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
4986 Renal Bx, Electron Microscopy No No
20500 RenalPath, Level IV, Wet Ts No No
9840 Periodic Acid-Schiff (PAS) ST No No
9828 Masson's Trichrome ST for Conn Ts No No
9889 Jones' Methenamine Silver ST No No
84226 Immunofluorescent C4d Stain No No
60301 IgA IF, Renal No No
60302 IgG IF, Renal No No
60304 Lambda IF, Renal No No
60305 Kappa IF, Renal No No
60306 C1q IF, Renal No No
60307 C3 IF, Renal No No
60308 Albumin IF, Renal No No
60309 Fibrinogen IF, Renal No No
60328 IgG1 IF, Renal No No
60329 IgG2 IF, Renal No No
60330 IgG3 IF, Renal No No
60331 IgG4 IF, Renal No No
60285 C1q Paraffin IF, Renal No No
60287 IgA Paraffin IF, Renal No No
60288 IgG Paraffin IF, Renal No No
60289 IgM Paraffin IF, Renal No No
60290 Kappa Paraffin IF, Renal No No
60291 Lambda Paraffin IF, Renal No No
60303 IgM IF, Renal No No
62196 RenalPath Consult, Outside Slide No, (Bill Only) No
62197 RenalPath Consult, w/Slide Prep No, (Bill Only) No
62198 RenalPath Consult, w/Comp Rvw of His No, (Bill Only) 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.


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.


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.


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.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type


Source: Kidney

Container/Tube: Renal Biopsy Kit (T231)

Specimen Volume: Entire specimen

Collection Instructions: Collect specimens according to the instructions in Renal Biopsy Procedure for Handling Tissue for Light Microscopy (LM), Immunofluorescent Histology (IF), and Electron Microscopy (EM) in Special Instructions.

Additional Information:

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


1. Renal Biopsy Patient Information in Special Instructions

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


Specimen Stability Information

Specimen Type Temperature Time
Tissue Ambient (preferred)

Reference Values

An interpretive report will be provided.

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.

CPT Code Information

Standard wet/unprocessed tissue consult:

88305-Surgical pathology, gross and microscopic examination (for kidney biopsy)

88321-Consultation and report on referred slides prepared elsewhere (for review of sent in slides for light microscopy)

88313-Special stain, including interpretation and report, group II (x3 - PAS, Jones, and Trichrome)

88346-Immunofluorescence study, initial antibody

88350-Immunofluorescence study, each add’l antibody (x8)

88348-Electron microscopy, diagnostic


If indicated:

88323-Consultation and report on referred material requiring preparation of slides (for review of sent in slides for light microscopy with additional preparation of light microscopy slides)

88325-Consultation, comprehensive with review of records and specimens with report on referred material (for sent in slides for light microscopy with comprehensive review of clinical info, labs, etc.)

88350-Immunofluorescence study, C4d (for transplant biopsies)

LOINC Code Information

Result ID Test Result Name Result LOINC Value
70066 Accession Number 57723-9
70067 Referring Pathologist/Physician 46608-6
70068 Ref Path/Phys Address 74221-3
70069 Final Diagnosis: 34574-4
70070 Comment: 48767-8
70071 Microscopic Description: 22635-7
70072 Special Studies: 30954-2
70073 Signing Pathologist: 19139-5
70074 Specimen: 31208-2
70075 Material: In Process
70076 Tissue Description: 22634-0
70077 *Previous Report Follows* No LOINC Needed
70078 Addendum: 35265-8
70079 Addendum Comment: 22638-1

Reject Due To









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.

Method Name

Pathology Consultation