Living Well Inspecting pee used to be all the rage...
The trend really got underway in the Middle Ages. Aside from the consistency, smell, and presence of any solids floating around, color was the most important diagnostic tool in uroscopy, or evaluating urine.
Similar to a Pantone color chart, medieval doctors would refer to a chart depicting round-bottomed "matula" flasks containing urine samples of various colors. The physicians would hold the pee-filled flask up to the light to check the color, do a sniff test, and look for solids or sediment.
Oh, and they'd take a sip, too.
A sweet taste helped them figure out whether a patient had diabetes. Thankfully, we have a less-disgusting way of diagnosing it now. But the color in your porcelain throne can still be useful in clueing you in to what may be happening in your body...
Your pee contains at least 95% water. The remaining 5% contains urea, creatinine, salts, and some other components in small amounts. As to what lends urine its color, you can thank your body's recycling program of your red blood cells ("RBCs"). Old ones get broken down to create a yellow pigment.
You've probably learned in grade school how RBCs carry oxygen by way of a protein called hemoglobin. Well, when old RBCs get broken down, heme (which also happens to contain iron) molecules in hemoglobin get released.
That heme gets transformed into bilirubin, a yellowish substance found in bile. (Bile is a digestive juice stored in the gallbladder and pumped out by the liver to your gut.) This process creates the majority (or about 80%) of bilirubin in your body. (The other 20% of bilirubin comes from heme found in proteins other than hemoglobin.) A study published earlier this year found that an enzyme called bilirubin reductase helps change the bile to urobilinogen, the precursor to urochrome which lends urine its yellow color.
As for the optimal urine color, you want a pale yellow that's clear. It's OK if it's a light honey color – that just means you're slightly dehydrated and drinking some water should help your urochrome right the ship itself. Dark, smelly urine means you're very dehydrated.
Here are some other ways urine can appear and what that could mean...
Colorless: You're very hydrated, or perhaps it might be a diuretic beverage (like coffee and alcohol) or medication causing it. Kidney problems or diabetes can make you pee a lot of transparent urine multiple times a day.
Cloudy: Dehydration can also cause this. But prolonged cloudy urine accompanied by new symptoms like painful and frequent urination may indicate a urinary tract infection ("UTI"). Your risk of developing a UTI increases as you get older. And it can show up in some bizarre, unexpected ways – current subscribers to my Retirement Millionaire newsletter can check out my issue covering UTIs here. Or get all the details on a trial subscription here.
Foamy: This is usually from proteins – which belong in your blood – getting released in urine. If bubbles become the norm, that indicates something could be wrong with your kidneys. Dehydration, fevers, and strenuous exercise can occasionally cause that foam.
Orange: A dark-yellow-to-orange color means you should chug some water right away. Eating lots of carrots, too much vitamin B2, or certain medications can also cause orange urine. Liver problems or gallstones blocking proper release of bile can cause bilirubin to get dumped back into your blood, which you end up peeing out.
Red and pink: This is blood in your urine, or hematuria, that can come from UTIs and kidney stones. It can even happen if you exercise too hard or if you have an enlarged prostate. Or your urine could be a reddish color because you've been eating too many beets and blackberries. Some medications like warfarin (a blood thinner) and senna (a laxative) can turn your urine from a pinot grigio color to a rose champagne.
Brown: Some antibiotics, antimalarial drugs, statins, laxatives, and muscle relaxers can cause brown urine. Speaking of muscles, peeing out what looks like iced tea – along with other symptoms like severe muscle pain, swelling, and weakness – can indicate rhabdomyolysis, a serious-but-rare condition where your muscle tissue breaks down and releases substances into your blood that can damage your kidneys. But don't worry – overdoing the rhubarb or fava beans can even cause cola-colored urine too.
Green, blue, and purple: Food dyes or dyes for certain bladder and kidney tests can lend a cool-toned hue. Certain drugs can be culprits, like indomethacin (for pain), amitriptyline (an antidepressant), cimetidine (for acid reflux), Uribel Tabs (for UTIs), and propofol (a sedative given during general anesthesia). Certain UTI-causing bacteria can also cause green urine. In rare cases, UTIs can result in purple urine in folks using catheters and urine bags.
Black and gray: This might happen in cases of melanoma skin cancer that has spread, where the urine blackens upon exposure to air. The same can be caused by a very rare genetic disorder called alkaptonuria.
Don't panic if you see a color other than the shade of lemonade in your toilet bowl. But if your at-home uroscopy shows a persistent alien shade and/or you develop new symptoms, then it's time to call your doctor.
What We're Reading...
- Recycling urine into drinking water in outer space.
- Something different: The final resting places of seven famous dogs.
Here's to our health, wealth, and a great retirement,
Dr. David Eifrig and the Health & Wealth Bulletin Research Team
August 27, 2024