Renal Biopsies – Gloms And Stuff
“Glom” (a term we toss around on the renal service) refers to the glomerulus, a nephron’s initial filtering component, which is often implicated in renal pathologies like multiple myeloma, amyloidosis, membranous disease, focal segmental glomerulosclerosis, membranoproliferate glomerulonephritis, etc. In the workup of patients with renal disease, sometimes all the lab tests are equivocal and necessitate a minimally invasive percutaneous renal biopsy under ultrasound guidance. As with all procedures, there are risks and benefits in achieving a tissue diagnosis.
For example, while the kidney parenchyma does not have pain receptors, the surrounding capsule contains nociceptors which can result in post-procedural discomfort. Furthermore, as the kidneys are HIGHLY vascular organs (they receive up to 20% of our total cardiac output!), post-biopsy bleeding is a very real concern. Patients who require kidney biopsies usually aren’t in great shape to begin with, so they’re more predisposed to develop hematomas and infections after the biopsy. Fortunately, these risks are well documented and cautionary measures are routinely utilized to minimize them.
Biopsy specimens are cut into sections for subsequent staining and microscopy – H&E, PAS, congo red, immunofluorescence, and electron microscopy are just a few destinations for these tissues. Renal biopsies are discussed face-to-face with the renal pathologist who assesses abnormalities within the nephron tubules, interstitium, glomeruli, and vessel beds. The gloms, in particular, are carefully analyzed for signs of podocyte effacement and infiltrative processes. A consensus is reached regarding the diagnosis, and a treatment regimen is started (expectant management, antivirals, steroids, more intense immunosuppression modalities, etc).
I’ve been lucky to see the entire process, from the interventional radiologist’s biopsy to the renal pathologist’s reading, several times this month. It’s another example of how far medicine has come in just the last few decades. 🙂