It was the usual sort of day in clinic and the team was seeing a middle aged woman with stable diabetic nephropathy and subnephrotic proteinuria. Her blood pressure and blood sugars had been well controlled since the last visit and being good nephrologists her urine specimen was spun and the sediment examined.
The team was shocked to find a packed field shown top left… Which became stranger under polarized light shown to the right…
Some of these objects were sort of hexagonal like cystine crystals but the patient had never had a kidney stone, never had this finding before and was much older than one would expect for a cystinuria presentation. The maltese cross finding was odd as well. Cystine crystals don't have these. The objects didn’t really look like oval fat bodies and the crosses were not the clean symmetric looking ones typically seen in these fat droplets.
The team, perplexed, split up taking the slide to the urinalysis lab to ask the techs if they knew what the heck this was, hitting pubmed and back to the patient to see if there was any funny business with the specimen.
On reconvening the answer was clear: corn starch. The techs instantly said they see it all the time when their gloves contaminate a specimen. Pubmed, gave us a nice case report from NDT Plus and the patient noted having some vulvar irritation and was likely using a corn starch based baby powder which had dropped into the specimen cup.
This is the part you can try at clinic…
To confirm our discovery I dipped one of our powdered gloves in water and then prepared it like a regular urine specimen. Perfect match. Give it a try in clinic next time you have some housestaff or unsuspecting renal co-fellows around.