NOTE: Johns Hopkins University Press, publisher of The Lupus Encyclopedia, is a nonprofit publisher. If you purchase JHUP books, like The Lupus Encyclopedia, you support projects like Project MUSE.
NOTE: Johns Hopkins Press, publisher of The Lupus Encyclopedia, is a nonprofit publishing house. Much of the proceeds goes toward projects like Project Muse
Doing a clean catch urine sample wrong can cause false results
Around 40% of systemic lupus erythematosus patients develop kidney inflammation (nephritis) and need to give a clean catch urine sample regularly. It is always essential to give a proper clean catch urine sample to ensure the results are accurate.
Some groups get it more often, as high as 80% in Afro-Caribbean women and 50-55% in African American women Finding excess protein in the urine (proteinuria) is how we identify lupus nephritis at its earliest stages.
How can the urine sample be inaccurate?
Contaminants from the vagina or foreskin, such as white or red blood cells, can artificially raise the amount of proteinuria.
If you collect it after exercising or in the late morning or afternoon, it can be artificially high (orthostatic proteinuria)
How to get a clean catch urine sample (PRINT THIS OUT AND KEEP IT HANDY):
Why this is important:
Correct collection saves you from repeating the test or doing a cumbersome 24-hour collection.
“What is the best time to take a urine sample?”
– Always try to collect your clean catch urine sample first thing in the morning (either the 1st or 2nd void) – Hydrate. Drink at least 8 glasses of water daily for a few days before the collection (unless your doctor has you on a water restriction)
Collect a mid-stream, clean catch urine sample:
– 1st wash your hands. – Carefully remove the lid from the urine sample cup, avoid touching the inside, and lay it inside-up.
– If you are giving a urine culture as well, to make sure you do not have a urinary tract infection, use a sterile cup. – Place the cup on an easy-to-reach surface.
How to give a urine sample female:
-Pull apart the labia (if you have them) with one hand. – Using your other hand, you wipe the urethra three times with three sterile wipes front to back. This is important. If you wipe back to the front, you can introduce bacteria around the anus that can potentially give you a urinary tract infection.
-Continue to keep the labia with one hand and grab the cup with the other hand.
How to give a urine sample male:
– retract the foreskin (if you have one) with one hand. – Using your other hand, you wipe the urethra three times with three sterile wipes. Keep the foreskin retracted with one hand and grab the cup with the other.
Next steps giving a urine sample for both sexes:
– First, urinate the initial couple of seconds into the toilet to clear bacteria from the urethra. Then, urinate into the cup to the fill line.
– You should empty the last part of your urine sample into the toilet again (which is why the term “midstream”). You should immediately put the lid securely on the cup, ensuring not to touch the inside of the cover or the container. – Secure the lid on the urine cup before flushing to prevent aerosol contamination.
“Can I give a urine sample with my period?
This is an important question. If you are asked to give a clean catch urine sample at a time when you are having any blood at all during your period, tell your doctor or the lab technician that you need to return on a day when you have no more bleeding at all. If red blood cells get into the urine sample, it will cause inaccurate readings of the amount of protein (it will be falsely elevated) and an increased number of red blood cells.
Urine Sample Abnormalities
Doctors examine many different parts of the urine. Most importantly, in lupus, they look for increased protein (proteinuria).
Other important potential abnormalities include those of the pH, concentration, white blood cell count, red blood cell count, and if there are casts or bacteria (bacteriuria) present.
How to Collect a 24 Hour Urine Sample
If the above is higher than normal, your doctor may order a 24 hour urine to measure protein and kidney function (creatinine clearance). It is incredibly important to follow these instructions perfectly. Collect the sample when you can be at home all day.
Collect 24 hour urine sample
You should collect every drop of urine during each 24-hour period, regardless of how much or little you pass each time.
· Begin the urine collection in the morning after you wake up, after you have emptied your bladder for the first time. · Urinate (empty the bladder) for the first time and flush it down the toilet. Note the exact time (eg, 6:15 AM). You will begin the urine collection at this time. · Into an empty collection bottle, collect every drop of urine during the day and night. · If you need to have a bowel movement, any urine passed with the bowel movement should be collected. Try not to include feces with the urine collection. If feces does get mixed in, do not try to remove the feces from the urine collection bottle. · Finish the collection with the first urine of the next morning, adding it to the collection bottle. This should be within five to ten minutes of the time of the first morning void on the first day (which was flushed, in this example, at 6:15 AM in this example). If you need to urinate one hour before the appointed time, drink a full glass of water so that you can void again at the appropriate time. If you have to urinate 20 minutes before, try to hold the urine until the proper time.
Please note the exact time of the final urination; even if it is not the same time as when collection began on day one, it is important that you accurately record the time of the final void.
Storage of 24 hour urine sample
The bottle(s) may be kept at normal room temperature for a day or two, but should be kept cool or refrigerated for longer periods of time.
Returning the 24 hour urine sample
Take the jug of urine back to our office on a weekday between 8:00AM – 11:30AM or 1:00PM – 1:30 PM.
When you drop off the urine, you must also provide a blood sample at the same time so we can determine how well your kidneys are working.
If the urine protein to creatinine ratio is more than 500 (or notated as 0.5 in some labs), we repeat the test and ask that the patient to make sure and drink lots of water and make sure the sample is the 1st or 2nd void of the day. If this repeat test is greater than 500 (or 0.5) a kidney biopsy is recommended to see if it is due to lupus nephritis or not. If it is lupus nephritis, then the biopsy can tell us which type it is, how bad it is, if it is treatable, and how much permanent damage has already occurred (If any).
If it is less than 500 (or 0.5) a biopsy is usually not done because it is unlikely that the biopsy will show lupus nephritis requiring immunosuppressant therapy. We typically watch it more closely and ensure the patient works on keeping their numbers perfect (blood pressure, glucose levels, cholesterol) and avoid things that can harm the kidneys (like NSAIDs and Chinese herbs).
However, an exception is if I have a patient with other risk factors for lupus nephritis, like a high anti-dsDNA, low complements, and a high anti-C1q antibody, or if the kidney function is lower, then I will get a kidney biopsy if the protein level is elevated but less than 500 (or 0.5).
Other causes of elevated protein in the urine
There are many other things that can cause elevated protein in the urine.
Exercise and standing or sitting for quite a while before the test can elevate the protein and is not a concern.
Other diseases can also elevate the protein level. These include things such as scar tissue from other disorders, damage from medications (like NSAIDs like ibuprofen and naproxen), and hardening of the arteries. Sometimes we can successfully guess the cause in the absence of a biopsy. An example would be a patient who has had a long history of elevated blood pressures (greater than 120/80) and then develops a mildly elevated protein level. The most likely cause in this scenario would be damage to the kidneys over the years from the high blood pressure. We call this hypertensive nephrosclerosis (fancy medical words for high blood pressure causing scarring of the kidneys). The treatment is to work on perfect blood pressure control.
You need to know a few lupus-related kidney problems that the lupus nephritis classification (which uses classes I through VI) doesn’t include. These other lupus kidney problems include inflammation of the blood vessels (vasculitis), damage to the kidney cells that form the microscopic kidney filters (lupus podocytopathy), and microscopic blood clots from antiphospholipid antibodies (antiphospholipid nephropathy). We treat the first two with immunosuppressants and the latter with blood thinners. All forms of lupus nephritis plus these last three entities also require hydroxychloroquine to help.
PRINT this out and keep it handy
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To properly collect a urine sample and understand the lab results, learn more here:
Just in case flushing could aerosolize other people’s germs that are hanging out in the toilet, I make a point to NOT flush the toilet until AFTER I’ve put the cap on the urine cup, put the cup into the little metal box in the wall, and closed the door to the little metal box. I don’t know how likely this is, but I don’t want to be told I have a UTI and be put on antibiotics unnecessarily due to someone else’s E. coli (or some other bacteria lurking in the toilet from people who used it before me) contaminating my urine sample. I never thought of this until I had to give a urine sample at my GYN’s office and they had very detailed instructions in a fancy frame sitting on a bathroom shelf right with all the necessary supplies … and their instructions said to put the cap on the urine cup before flushing the toilet… and then I thought about why they might have said to do things in that particular order.
I love that ANON. I am going to add that to the instructions when I publish the 2nd edition of my book. E coli does get aerosolized with flushes, so it makes sense to add this recommendation.
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