Renal biopsy (also kidney biopsy) is a medical procedure in which a small piece of kidney is removed from the body for examination, usually under a microscope. Microscopic examination of the tissue can provide information needed to diagnose, monitor or treat problems of the kidney.

1. HANDLING RENAL
BIOPSIES
ABDUL QUDDUS
BS-MLT

2. Indications of renal biopsy
•Unexplained acute or rapidly progressive renal failure
•Nephrotic syndrome and significant non-nephrotic proteinuria
•Persistent glomerular hematuria
•Systemic diseases with renal involvement
•Renal allograft dysfunction.

3. Required Information
 Label the containers with the patient’s name and a 2nd patient identifier such
as a date of birth or a medical record number.
 Detailed clinical history should be provided by the clinician.

4. RENAL BIOPSIES
 LIGHT MICROSCOPY
 IMMUNOFLUORESCENCE
 ELECTRON MICROSCOPY
 IMMUNOHISTOCHEMISTRY

5. Adequacy
 The minimum diagnostic sample size varies with the specific diagnosis; for
instance only one glomerulus is enough for making a diagnosis of membranous
glomerulonephritis while 25 glomeruli may be required to make an accurate
diagnosis of focal lesion like FSGS.
 For most of the light microscopic assessment, 8 - 10 glomeruli are considered
adequate.

6. Adequacy
 The adequacy of the renal tissue core should be assessed on - site using a
dissecting microscope.
 The tissue sample should be transferred using a wooden spatula to a glass
slide with few drops of saline and examined.
 Under a dissecting microscope, glomeruli appear as reddish, circular
structures while medulla is identified by red streaks running almost parallel.

8.  If possible, 2 - 3 cores should be taken: one for light microscopy (LM), another
for immunofluorescence(IF) and one for electron microscopy(EM), if required.
 In cases where taking extra passes is not possible, a cutting protocol may be
followed: both the ends of the core are taken for EM, one-third of the core,
including some glomeruli, is placed in transport medium for IF and the rest is
kept for LM.

11. Precautions while dividing renal tissue
cores
 Forceps should not be used, as they may lead to crush artefacts.
 Thin wooden stick, for example, a spatula or toothpick, is ideal.
 Avoid touching the tissue with a fixative-contaminated scalpel or blade; this
may contaminate the tissue meant for IF.

12. LIGHT MICROSCOPY
 The tissue sections should be no greater than 2-3 μm in thickness
 Good histology also demands good fixation. If fixation is delayed and
imperfect, it cannot be improved later.
 The most commonly used fixative for LM is buffered, 10% aqueous
formaldehyde solution (formalin).
 Some laboratories prefer alcoholic Bouin’s or Zenker’s fixatives for better
morphological details. However, these interfere with recovery of material for
EM, IHC or molecular studies.

13. Histochemical stains

14. IMMUNOFLUORESCENCE
 Immunofluorescence is best performed on unfixed, frozen sections.
 Tissue can be transported to the laboratory fresh on saline-soaked gauze or in
Michel's fixative.
 Serial sections are cut at 2-4 μm in a cryostat.
 IgG, IgM, and IgA, C3, C1q, C4, fibrin, and kappa and lambda light chains.

15. Electron Microscopy
 The tissue for EM may be fixed in 2-3% glutaraldehyde or 1-4%
paraformaldehyde.
 Adequate fixation can also be obtained when tissue is fixed in buffered
formalin.
 EM cannot be performed on tissues exposed to mercury-based fixatives (e.g.,
Zenker's).
 Tissue can be reprocessed from the paraffin or the frozen block if no
glomeruli are available in the EM sample.