The Urinalysis

More times than I care to think, I have heard the comment made by pet owners that "in-house urinalyses aren't as accurate as an outside lab's analysis."

Ouch.

What does that say about our profession as veterinary technicians? Well, let me spell it out. We're not doing our jobs! If you're like me, you want to elevate our profession where it belongs, as a significant and valuable asset to the veterinary medical field. But we're not going to do that if we're not willing to utilize the skills that we were taught or worse, we don't have those skills.

The first thing you need to do is check that you have the proper equipment available to you in your lab.

Centrifuge, capable of at least two speeds if possible.

Red top tubes for urine, NOT serum separators. If you use Antech Labs they send them free so just ask. Or better yet, pay for the conical shaped urine tubes available from your vet supply.

Refractometer in working order. Don't waste your time with a broken refractometer; if the hinge and/or cover is broken you can get one from one of your suppliers for about $35. A complete new one depends on which one you get and can be between about $175 and $325. Regardless, there's no excuse for not having a working refractometer. Get it.

Urine reagent strips, a jar of 100 available for about $35; don't bother with the ones that have the leukocyte pad, they're commonly inaccurate and almost always test positive. DO NOT USE EXPIRED REAGENT STRIPS! Throw them out and replace them!

Pipettes, slides and slide covers, cheap or available free through Antech.

Sedi-stain; now this stuff is a pain in the butt because it is so easily contaminated, but if you are careful you can keep it clean for a while and I've heard that you can autoclave it. Don't quote me on that though.

Last but not least you need a GOOD microscope with a 100x objective. If your practice doesn't have one then you need to prove to your vet(s)that you need one. Don't just ask for one, prove that you need it and will use it.

Oh, and in your clinic library you should have an up-to-date laboratory procedure book such as the "Pratt book" called Laboratory Procedures for Veterinary Technicians for reference.

Now we'll address procedure. I want pet owners and technicians alike to understand that our urinalysis can be as accurate as the big lab's. But the responsibility of upholding that expectation is up to us, the veterinary technician!

Practice practice practice. You may have to ask the vet to get more urine than they are accustomed to, but if they value your professionalism they'll be happy to do it. I don't know about other labs, but Antech prefers at least 5 cc of urine; you need at least 3 cc. Do your analysis even if the vet wants to send it in to the lab. All the better, practice requires confirmation. Keep a record of your analysis and compare it to the lab results. Your results and the labs should be the same; they don't have to be exact but they should both lead your veterinarian to the same diagnosis.

The first step is obtaining the urine. There are three ways urine is collected; cystocentesis, catheterization and free catch (voided or expressed).

Free catch should only be used as a last resort. This should be only used for a quick and dirty (literally) look at the urine under the scope for crystals, casts and blood cells. Followed up later with a cleaner method.

Catheterization of male dogs is how some vets prefer to collect their urine since a simple poke to the bladder often results in a free catch sample. I've only seen one dog suffer negatively from catheterization and that was a male Sheltie while I was in tech school that was catheterized at least four times in 24 hours. Blocked male cats while anesthetized are catheterized which will enable you to see what kind of crystals and if there's an infection. It can be done on the female of each species, but I've seldom seen it performed where I was previously employed.

Cystocentesis is the best method to collect the urine, especially if the vet orders a culture and sensitivity test. Which I hope is done more often than I have seen, another responsibility that veterinary technicians may be shirking - not the c/s itself but educating clients about how important culture and sensitivity tests are to their pets' health. Read more about that in So your Dog has Struvites.

The assurance of quality starts with the proper collection and handling of the samples. Label your sample immediately and perform your analysis ASAP. Remember that cell morphology deteriorates quickly in urine so take the necessary steps to preserve it. Most other constituents of urine can be preserved for 6 to 12 hours in the refrigerator. Just be sure to warm it to room temperature before evaluation.

This is where the technician has the upper hand in analysis. Most urine samples "sent out" are only picked up once or twice a day (AM and PM pickups for the busier hospitals and PM pickups for the smaller practices). The chances of cytological changes and deterioration are greatly effected by this lag time between the time of collection and analysis. At my former employment we could acquire the sample at 11:30 am, the pick up is at 5:15 pm and then it's sometimes flown down to Irvine, CA for analysis! It can be more than 12 hours before the sample is analyzed.

We've got our urine, we've packed and prepared the outside lab sample for pickup and we have our sample ready to go, too.

First is the gross evaluation. Did you ever think that your career would involve staring at urine and poop? Haha. We're going to skip the first evaluation which is urine output for obvious reasons.

We look at the color. Is it normal yellow? Record the color you see. The more concentrated the urine the darker it will be and if it's very dilute it will be paler. Red/brown would signify hemoglobin or RBCs in the urine. Yellow/brown or greenish could contain bile pigments. It's very important to record the color seen.

Is the urine clear, cloudy or have chunky stuff floating around (called flocculent)? Cloudiness can be attributed to RBCs, WBCs, epithelials, casts, fat, mucus, bacteria and crystals, and you'll figure that out when you view the sediment under the scope. Record what you see.

Is there a lot of foam produced when you shake the sample? A little foam is normal, a lot of foam is usually indicative of protein and yellow/green foam alerts you to bile pigments present. Record this under "appearance" as well.

The next task is to determine the specific gravity (SG) of the urine. This is an important assay to perform on the urine. Please do not waste your time reading the reagent pad for SG; it's simply not accurate enough and should be evaluated with a refractometer. Place a few drops on the window of the refractometer, close the cover and view through the eye piece. If you're unfamiliar with using a refractometer find someone who is or you can contact me privately. The SG for dogs should be about 1.025 and be in the range of 1.018-1.045 for cats between 1.020 and 1.040 with 1.030 being the average. Most refractometers read up to 1.040 and if it goes over that mark it should be noted as >1.040 in the record. Either too low or too high of a SG can be of great significance to the veterinarian when making their diagnosis.

We've now arrived at the reagent strips. This is actually an area that technicians and assistants can fall down on when comparing results with that of the outside labs. The reagent strips are for quick results and should not be used alone for diagnosis. That's just laziness, folks, and it does nothing for the profession when we rely solely on reagent strips. I've seen results to urinalyses posted by pet owners where there's nothing about sediment analysis. NOT GOOD!

The other thing that sets us apart is that even though the labs also use reagent strips, they also may have reflectant spectometry instruments that eliminate the possible human error of color perception. Regardless, your results should be in the ballpark of the lab's and should allow the vet to come to the same diagnosis. The pads to read are pH, protein, glucose, ketones, bilirubin, nitrites and, if it's available on your stick, urobilinogen. Record your evaluation of the reagent strip. If you note a presence of red blood cells according to the strip, mentally note it and be aware that they could be seen in your sediment evaluation.

I hope that while doing your SG and reagent strip you were centrifuging your urine sample, about 3-5 minutes at 1000-2000 rpm. Whether you can see sediment or not, always assume there is some, and pour off the supernant leaving about 0.3 cc urine, and gently mix the remaining urine with the sediment. Place a small amount of the now suspended sediment on a clean slide and cover with a cover slip to be examined immediately. THIS IS WHERE WE CAN SHINE!

Learning to read sediment is very important, especially if you can read it unstained. I highly recommend having a text with quality photographs sitting right next to you. LEARN to use your microscope properly and LEARN to identify crystals, casts, the different epithelial cells, RBCs and WBCs, spermatozoa, parasites and lipids. If there's interest I can go over the different crystals, casts and epithelial cells, when you would see them and what their presence signifies. The better you become at in-house urinalysis the better your can serve your clients.

Technicians: Check VSPN regularly for online classes available regarding urinalysis. Ask your vet to alert you to any CEs that may be going on in your area. If there's a veterinary technician program in your area you can also contact them about lectures that may be coming up. I know that the college I graduated from always sends out notices to the area hospitals/clinics regarding lectures.

Take pride in your profession, expand your knowledge and increase your professional value!