Urine for a treat: Urinary sediment 101

In this episode, Drs. Young, Ambruso & Mortaji discuss the ABCs of urinalysis and urinary sediment, They are joined by the acclaimed nephrologist and self-proclaimed "piss-prophet" Dr. Juan Carlo Velez, Department Chair at Oschner Medical Center in New Olreans, LA. You can find Dr. Velez's other podcast at "Channel Your Enthusiasm  - The Burton Rose Book Club". Also, check out Dr. Velez at his Twitter handle @VelezNephHepato

Edited by: Parisa Mortaji, MD & Sophia Ambruso, DO

Sophia Ambruso DO @Sophia_Kidney, Sarah Young MD @kidneycritic, Judy Blaine MD, Parisa Mortaji, MD

Transcript

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This podcast we are going to discuss the nuts & bolts of urine microscopy  and in the 2nd podcast we will review some cases

Parisa: Whats great about urine microscopy is it is available to almost all patients, relatively easy to perform and is inexpensive

Sophie:  Overall, there seems to be waning physician competence,. At my institution, we are not officially able to refer to it as a lab result, not “qualified” but apparently the lab techs are?? …. I personally think the lab interpretation is often inaccurate and I am inclined to rely on my interpretation.

So anyways, to get around those regulations, I’ll often report my interpretation as an extension of my physical exam. 

Well,  luckily we have Juan carlos on  this podcast… Juan carlos,  as his twitter account is proof. Is an expert in urine microscopy and he clearly has a very nice microscope…so Juan Carlos walk us through how you collect the urine and prepare your slide

Juan Carlos:

• Collect a fresh urine specimen (spontaneous is preferable)
• Urine from a foley should be withdrawn directly from the tube as opposed to the urometer
• Look at the urine within 1-2 hours
• 10ml centrifuged for 5min at 1500rpm
• Decant the top 9.5ml
• Resuspend the sediment
• Single drop on slide with a cover slip
• Stain use

Parisa: What power do you use? 

Juan Carlos: review the very concrete mechanisms by which you begin viewing the urine under the microscopsy

Number of fields

Level of magnificantion

Parisa: can you walk us through the different types of microscopes- brightfield vs phase contrast:

Juan Carlos: brightfield vs phase contrast

Phase contrast: improves ID of cells, casts

Polarized light needed for lipids, crystals

Sarah: Sophie, anything else you do? 

Sophie- I like to look at the coverfield edges where casts generally collect.

Sarah:Juan carlos why don’t we review the important elements we are looking for on microscopy, lets start with erythrocytes

Juan Carlos: discuss isomorphic vs dysmorphic vs acanthocytes 

Parisa- what is the mechanism by which the rbc become dysmorphic?

Juan carlos responds

Sophie- mention there is no agreement on criteria to classify hematuria as glomerular. What do you use Juan carlos? 80% dysmorphic? Any dysmorphic?

JC- responds

Sarah: the criteria i was always taught was 40%dysmorphic and/or 5% acanthocytes and/or 1 rbc casts gives you glomerular hematuria

Responses from everyone

Sarah: lets move on to leukocytes

JC- urinary leukocytes- neutrophil, eosinophils (require a hansel stain to ID), leukocytes macrophages

Parisa: what do RTEC look like and how do u differentiate them from other cells?

JC

Sarah- lets move on to casts and leave crystals for another podcast

Casts: acellular (granular, hyaline), cellular (RTEC,RBC,WBC)

Crystals

Learning objectives:

sophie

• Standardized collection of urine specimen
  • Fresh specimen, centrifuge for 5min n]for 1500rpm
• Elements of urine 
  • Rbc,wbc,RTEC cellular and acellular casts